This is gdb.info, produced by makeinfo version 6.3 from gdb.texinfo. Copyright (C) 1988-2017 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Free Software" and "Free Software Needs Free Documentation", with the Front-Cover Texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. (a) The FSF's Back-Cover Text is: "You are free to copy and modify this GNU Manual. Buying copies from GNU Press supports the FSF in developing GNU and promoting software freedom." INFO-DIR-SECTION Software development START-INFO-DIR-ENTRY * Gdb: (gdb). The GNU debugger. * gdbserver: (gdb) Server. The GNU debugging server. END-INFO-DIR-ENTRY This file documents the GNU debugger GDB. This is the Tenth Edition, of 'Debugging with GDB: the GNU Source-Level Debugger' for GDB (GDB) Version 8.0.1. Copyright (C) 1988-2017 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being "Free Software" and "Free Software Needs Free Documentation", with the Front-Cover Texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. (a) The FSF's Back-Cover Text is: "You are free to copy and modify this GNU Manual. Buying copies from GNU Press supports the FSF in developing GNU and promoting software freedom."  File: gdb.info, Node: Guile Auto-loading, Next: Guile Modules, Prev: Guile API, Up: Guile 23.3.4 Guile Auto-loading ------------------------- When a new object file is read (for example, due to the 'file' command, or because the inferior has loaded a shared library), GDB will look for Guile support scripts in two ways: 'OBJFILE-gdb.scm' and the '.debug_gdb_scripts' section. *Note Auto-loading extensions::. The auto-loading feature is useful for supplying application-specific debugging commands and scripts. Auto-loading can be enabled or disabled, and the list of auto-loaded scripts can be printed. 'set auto-load guile-scripts [on|off]' Enable or disable the auto-loading of Guile scripts. 'show auto-load guile-scripts' Show whether auto-loading of Guile scripts is enabled or disabled. 'info auto-load guile-scripts [REGEXP]' Print the list of all Guile scripts that GDB auto-loaded. Also printed is the list of Guile scripts that were mentioned in the '.debug_gdb_scripts' section and were not found. This is useful because their names are not printed when GDB tries to load them and fails. There may be many of them, and printing an error message for each one is problematic. If REGEXP is supplied only Guile scripts with matching names are printed. Example: (gdb) info auto-load guile-scripts Loaded Script Yes scm-section-script.scm full name: /tmp/scm-section-script.scm No my-foo-pretty-printers.scm When reading an auto-loaded file, GDB sets the "current objfile". This is available via the 'current-objfile' procedure (*note Objfiles In Guile::). This can be useful for registering objfile-specific pretty-printers.  File: gdb.info, Node: Guile Modules, Prev: Guile Auto-loading, Up: Guile 23.3.5 Guile Modules -------------------- GDB comes with several modules to assist writing Guile code. * Menu: * Guile Printing Module:: Building and registering pretty-printers * Guile Types Module:: Utilities for working with types  File: gdb.info, Node: Guile Printing Module, Next: Guile Types Module, Up: Guile Modules 23.3.5.1 Guile Printing Module .............................. This module provides a collection of utilities for working with pretty-printers. Usage: (use-modules (gdb printing)) -- Scheme Procedure: prepend-pretty-printer! object printer Add PRINTER to the front of the list of pretty-printers for OBJECT. The OBJECT must either be a '' object, or '#f' in which case PRINTER is added to the global list of printers. -- Scheme Procecure: append-pretty-printer! object printer Add PRINTER to the end of the list of pretty-printers for OBJECT. The OBJECT must either be a '' object, or '#f' in which case PRINTER is added to the global list of printers.  File: gdb.info, Node: Guile Types Module, Prev: Guile Printing Module, Up: Guile Modules 23.3.5.2 Guile Types Module ........................... This module provides a collection of utilities for working with '' objects. Usage: (use-modules (gdb types)) -- Scheme Procedure: get-basic-type type Return TYPE with const and volatile qualifiers stripped, and with typedefs and C++ references converted to the underlying type. C++ example: typedef const int const_int; const_int foo (3); const_int& foo_ref (foo); int main () { return 0; } Then in gdb: (gdb) start (gdb) guile (use-modules (gdb) (gdb types)) (gdb) guile (define foo-ref (parse-and-eval "foo_ref")) (gdb) guile (get-basic-type (value-type foo-ref)) int -- Scheme Procedure: type-has-field-deep? type field Return '#t' if TYPE, assumed to be a type with fields (e.g., a structure or union), has field FIELD. Otherwise return '#f'. This searches baseclasses, whereas 'type-has-field?' does not. -- Scheme Procedure: make-enum-hashtable enum-type Return a Guile hash table produced from ENUM-TYPE. Elements in the hash table are referenced with 'hashq-ref'.  File: gdb.info, Node: Auto-loading extensions, Next: Multiple Extension Languages, Prev: Guile, Up: Extending GDB 23.4 Auto-loading extensions ============================ GDB provides two mechanisms for automatically loading extensions when a new object file is read (for example, due to the 'file' command, or because the inferior has loaded a shared library): 'OBJFILE-gdb.EXT' and the '.debug_gdb_scripts' section of modern file formats like ELF. * Menu: * objfile-gdb.ext file: objfile-gdbdotext file. The 'OBJFILE-gdb.EXT' file * .debug_gdb_scripts section: dotdebug_gdb_scripts section. The '.debug_gdb_scripts' section * Which flavor to choose?:: The auto-loading feature is useful for supplying application-specific debugging commands and features. Auto-loading can be enabled or disabled, and the list of auto-loaded scripts can be printed. See the 'auto-loading' section of each extension language for more information. For GDB command files see *note Auto-loading sequences::. For Python files see *note Python Auto-loading::. Note that loading of this script file also requires accordingly configured 'auto-load safe-path' (*note Auto-loading safe path::).  File: gdb.info, Node: objfile-gdbdotext file, Next: dotdebug_gdb_scripts section, Up: Auto-loading extensions 23.4.1 The 'OBJFILE-gdb.EXT' file --------------------------------- When a new object file is read, GDB looks for a file named 'OBJFILE-gdb.EXT' (we call it SCRIPT-NAME below), where OBJFILE is the object file's name and where EXT is the file extension for the extension language: 'OBJFILE-gdb.gdb' GDB's own command language 'OBJFILE-gdb.py' Python 'OBJFILE-gdb.scm' Guile SCRIPT-NAME is formed by ensuring that the file name of OBJFILE is absolute, following all symlinks, and resolving '.' and '..' components, and appending the '-gdb.EXT' suffix. If this file exists and is readable, GDB will evaluate it as a script in the specified extension language. If this file does not exist, then GDB will look for SCRIPT-NAME file in all of the directories as specified below. Note that loading of these files requires an accordingly configured 'auto-load safe-path' (*note Auto-loading safe path::). For object files using '.exe' suffix GDB tries to load first the scripts normally according to its '.exe' filename. But if no scripts are found GDB also tries script filenames matching the object file without its '.exe' suffix. This '.exe' stripping is case insensitive and it is attempted on any platform. This makes the script filenames compatible between Unix and MS-Windows hosts. 'set auto-load scripts-directory [DIRECTORIES]' Control GDB auto-loaded scripts location. Multiple directory entries may be delimited by the host platform path separator in use (':' on Unix, ';' on MS-Windows and MS-DOS). Each entry here needs to be covered also by the security setting 'set auto-load safe-path' (*note set auto-load safe-path::). This variable defaults to '$debugdir:$datadir/auto-load'. The default 'set auto-load safe-path' value can be also overriden by GDB configuration option '--with-auto-load-dir'. Any reference to '$debugdir' will get replaced by DEBUG-FILE-DIRECTORY value (*note Separate Debug Files::) and any reference to '$datadir' will get replaced by DATA-DIRECTORY which is determined at GDB startup (*note Data Files::). '$debugdir' and '$datadir' must be placed as a directory component -- either alone or delimited by '/' or '\' directory separators, depending on the host platform. The list of directories uses path separator (':' on GNU and Unix systems, ';' on MS-Windows and MS-DOS) to separate directories, similarly to the 'PATH' environment variable. 'show auto-load scripts-directory' Show GDB auto-loaded scripts location. 'add-auto-load-scripts-directory [DIRECTORIES...]' Add an entry (or list of entries) to the list of auto-loaded scripts locations. Multiple entries may be delimited by the host platform path separator in use. GDB does not track which files it has already auto-loaded this way. GDB will load the associated script every time the corresponding OBJFILE is opened. So your '-gdb.EXT' file should be careful to avoid errors if it is evaluated more than once.  File: gdb.info, Node: dotdebug_gdb_scripts section, Next: Which flavor to choose?, Prev: objfile-gdbdotext file, Up: Auto-loading extensions 23.4.2 The '.debug_gdb_scripts' section --------------------------------------- For systems using file formats like ELF and COFF, when GDB loads a new object file it will look for a special section named '.debug_gdb_scripts'. If this section exists, its contents is a list of null-terminated entries specifying scripts to load. Each entry begins with a non-null prefix byte that specifies the kind of entry, typically the extension language and whether the script is in a file or inlined in '.debug_gdb_scripts'. The following entries are supported: 'SECTION_SCRIPT_ID_PYTHON_FILE = 1' 'SECTION_SCRIPT_ID_SCHEME_FILE = 3' 'SECTION_SCRIPT_ID_PYTHON_TEXT = 4' 'SECTION_SCRIPT_ID_SCHEME_TEXT = 6' 23.4.2.1 Script File Entries ............................ If the entry specifies a file, GDB will look for the file first in the current directory and then along the source search path (*note Specifying Source Directories: Source Path.), except that '$cdir' is not searched, since the compilation directory is not relevant to scripts. File entries can be placed in section '.debug_gdb_scripts' with, for example, this GCC macro for Python scripts. /* Note: The "MS" section flags are to remove duplicates. */ #define DEFINE_GDB_PY_SCRIPT(script_name) \ asm("\ .pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n\ .byte 1 /* Python */\n\ .asciz \"" script_name "\"\n\ .popsection \n\ "); For Guile scripts, replace '.byte 1' with '.byte 3'. Then one can reference the macro in a header or source file like this: DEFINE_GDB_PY_SCRIPT ("my-app-scripts.py") The script name may include directories if desired. Note that loading of this script file also requires accordingly configured 'auto-load safe-path' (*note Auto-loading safe path::). If the macro invocation is put in a header, any application or library using this header will get a reference to the specified script, and with the use of '"MS"' attributes on the section, the linker will remove duplicates. 23.4.2.2 Script Text Entries ............................ Script text entries allow to put the executable script in the entry itself instead of loading it from a file. The first line of the entry, everything after the prefix byte and up to the first newline ('0xa') character, is the script name, and must not contain any kind of space character, e.g., spaces or tabs. The rest of the entry, up to the trailing null byte, is the script to execute in the specified language. The name needs to be unique among all script names, as GDB executes each script only once based on its name. Here is an example from file 'py-section-script.c' in the GDB testsuite. #include "symcat.h" #include "gdb/section-scripts.h" asm( ".pushsection \".debug_gdb_scripts\", \"MS\",@progbits,1\n" ".byte " XSTRING (SECTION_SCRIPT_ID_PYTHON_TEXT) "\n" ".ascii \"gdb.inlined-script\\n\"\n" ".ascii \"class test_cmd (gdb.Command):\\n\"\n" ".ascii \" def __init__ (self):\\n\"\n" ".ascii \" super (test_cmd, self).__init__ (" "\\\"test-cmd\\\", gdb.COMMAND_OBSCURE)\\n\"\n" ".ascii \" def invoke (self, arg, from_tty):\\n\"\n" ".ascii \" print (\\\"test-cmd output, arg = %s\\\" % arg)\\n\"\n" ".ascii \"test_cmd ()\\n\"\n" ".byte 0\n" ".popsection\n" ); Loading of inlined scripts requires a properly configured 'auto-load safe-path' (*note Auto-loading safe path::). The path to specify in 'auto-load safe-path' is the path of the file containing the '.debug_gdb_scripts' section.  File: gdb.info, Node: Which flavor to choose?, Prev: dotdebug_gdb_scripts section, Up: Auto-loading extensions 23.4.3 Which flavor to choose? ------------------------------ Given the multiple ways of auto-loading extensions, it might not always be clear which one to choose. This section provides some guidance. Benefits of the '-gdb.EXT' way: * Can be used with file formats that don't support multiple sections. * Ease of finding scripts for public libraries. Scripts specified in the '.debug_gdb_scripts' section are searched for in the source search path. For publicly installed libraries, e.g., 'libstdc++', there typically isn't a source directory in which to find the script. * Doesn't require source code additions. Benefits of the '.debug_gdb_scripts' way: * Works with static linking. Scripts for libraries done the '-gdb.EXT' way require an objfile to trigger their loading. When an application is statically linked the only objfile available is the executable, and it is cumbersome to attach all the scripts from all the input libraries to the executable's '-gdb.EXT' script. * Works with classes that are entirely inlined. Some classes can be entirely inlined, and thus there may not be an associated shared library to attach a '-gdb.EXT' script to. * Scripts needn't be copied out of the source tree. In some circumstances, apps can be built out of large collections of internal libraries, and the build infrastructure necessary to install the '-gdb.EXT' scripts in a place where GDB can find them is cumbersome. It may be easier to specify the scripts in the '.debug_gdb_scripts' section as relative paths, and add a path to the top of the source tree to the source search path.  File: gdb.info, Node: Multiple Extension Languages, Next: Aliases, Prev: Auto-loading extensions, Up: Extending GDB 23.5 Multiple Extension Languages ================================= The Guile and Python extension languages do not share any state, and generally do not interfere with each other. There are some things to be aware of, however. 23.5.1 Python comes first ------------------------- Python was GDB's first extension language, and to avoid breaking existing behaviour Python comes first. This is generally solved by the "first one wins" principle. GDB maintains a list of enabled extension languages, and when it makes a call to an extension language, (say to pretty-print a value), it tries each in turn until an extension language indicates it has performed the request (e.g., has returned the pretty-printed form of a value). This extends to errors while performing such requests: If an error happens while, for example, trying to pretty-print an object then the error is reported and any following extension languages are not tried.  File: gdb.info, Node: Aliases, Prev: Multiple Extension Languages, Up: Extending GDB 23.6 Creating new spellings of existing commands ================================================ It is often useful to define alternate spellings of existing commands. For example, if a new GDB command defined in Python has a long name to type, it is handy to have an abbreviated version of it that involves less typing. GDB itself uses aliases. For example 's' is an alias of the 'step' command even though it is otherwise an ambiguous abbreviation of other commands like 'set' and 'show'. Aliases are also used to provide shortened or more common versions of multi-word commands. For example, GDB provides the 'tty' alias of the 'set inferior-tty' command. You can define a new alias with the 'alias' command. 'alias [-a] [--] ALIAS = COMMAND' ALIAS specifies the name of the new alias. Each word of ALIAS must consist of letters, numbers, dashes and underscores. COMMAND specifies the name of an existing command that is being aliased. The '-a' option specifies that the new alias is an abbreviation of the command. Abbreviations are not shown in command lists displayed by the 'help' command. The '--' option specifies the end of options, and is useful when ALIAS begins with a dash. Here is a simple example showing how to make an abbreviation of a command so that there is less to type. Suppose you were tired of typing 'disas', the current shortest unambiguous abbreviation of the 'disassemble' command and you wanted an even shorter version named 'di'. The following will accomplish this. (gdb) alias -a di = disas Note that aliases are different from user-defined commands. With a user-defined command, you also need to write documentation for it with the 'document' command. An alias automatically picks up the documentation of the existing command. Here is an example where we make 'elms' an abbreviation of 'elements' in the 'set print elements' command. This is to show that you can make an abbreviation of any part of a command. (gdb) alias -a set print elms = set print elements (gdb) alias -a show print elms = show print elements (gdb) set p elms 20 (gdb) show p elms Limit on string chars or array elements to print is 200. Note that if you are defining an alias of a 'set' command, and you want to have an alias for the corresponding 'show' command, then you need to define the latter separately. Unambiguously abbreviated commands are allowed in COMMAND and ALIAS, just as they are normally. (gdb) alias -a set pr elms = set p ele Finally, here is an example showing the creation of a one word alias for a more complex command. This creates alias 'spe' of the command 'set print elements'. (gdb) alias spe = set print elements (gdb) spe 20  File: gdb.info, Node: Interpreters, Next: TUI, Prev: Extending GDB, Up: Top 24 Command Interpreters *********************** GDB supports multiple command interpreters, and some command infrastructure to allow users or user interface writers to switch between interpreters or run commands in other interpreters. GDB currently supports two command interpreters, the console interpreter (sometimes called the command-line interpreter or CLI) and the machine interface interpreter (or GDB/MI). This manual describes both of these interfaces in great detail. By default, GDB will start with the console interpreter. However, the user may choose to start GDB with another interpreter by specifying the '-i' or '--interpreter' startup options. Defined interpreters include: 'console' The traditional console or command-line interpreter. This is the most often used interpreter with GDB. With no interpreter specified at runtime, GDB will use this interpreter. 'mi' The newest GDB/MI interface (currently 'mi2'). Used primarily by programs wishing to use GDB as a backend for a debugger GUI or an IDE. For more information, see *note The GDB/MI Interface: GDB/MI. 'mi2' The current GDB/MI interface. 'mi1' The GDB/MI interface included in GDB 5.1, 5.2, and 5.3. You may execute commands in any interpreter from the current interpreter using the appropriate command. If you are running the console interpreter, simply use the 'interpreter-exec' command: interpreter-exec mi "-data-list-register-names" GDB/MI has a similar command, although it is only available in versions of GDB which support GDB/MI version 2 (or greater). Note that 'interpreter-exec' only changes the interpreter for the duration of the specified command. It does not change the interpreter permanently. Although you may only choose a single interpreter at startup, it is possible to run an independent interpreter on a specified input/output device (usually a tty). For example, consider a debugger GUI or IDE that wants to provide a GDB console view. It may do so by embedding a terminal emulator widget in its GUI, starting GDB in the traditional command-line mode with stdin/stdout/stderr redirected to that terminal, and then creating an MI interpreter running on a specified input/output device. The console interpreter created by GDB at startup handles commands the user types in the terminal widget, while the GUI controls and synchronizes state with GDB using the separate MI interpreter. To start a new secondary "user interface" running MI, use the 'new-ui' command: new-ui INTERPRETER TTY The INTERPRETER parameter specifies the interpreter to run. This accepts the same values as the 'interpreter-exec' command. For example, 'console', 'mi', 'mi2', etc. The TTY parameter specifies the name of the bidirectional file the interpreter uses for input/output, usually the name of a pseudoterminal slave on Unix systems. For example: (gdb) new-ui mi /dev/pts/9 runs an MI interpreter on '/dev/pts/9'.  File: gdb.info, Node: TUI, Next: Emacs, Prev: Interpreters, Up: Top 25 GDB Text User Interface ************************** * Menu: * TUI Overview:: TUI overview * TUI Keys:: TUI key bindings * TUI Single Key Mode:: TUI single key mode * TUI Commands:: TUI-specific commands * TUI Configuration:: TUI configuration variables The GDB Text User Interface (TUI) is a terminal interface which uses the 'curses' library to show the source file, the assembly output, the program registers and GDB commands in separate text windows. The TUI mode is supported only on platforms where a suitable version of the 'curses' library is available. The TUI mode is enabled by default when you invoke GDB as 'gdb -tui'. You can also switch in and out of TUI mode while GDB runs by using various TUI commands and key bindings, such as 'tui enable' or 'C-x C-a'. *Note TUI Commands: TUI Commands, and *note TUI Key Bindings: TUI Keys.  File: gdb.info, Node: TUI Overview, Next: TUI Keys, Up: TUI 25.1 TUI Overview ================= In TUI mode, GDB can display several text windows: _command_ This window is the GDB command window with the GDB prompt and the GDB output. The GDB input is still managed using readline. _source_ The source window shows the source file of the program. The current line and active breakpoints are displayed in this window. _assembly_ The assembly window shows the disassembly output of the program. _register_ This window shows the processor registers. Registers are highlighted when their values change. The source and assembly windows show the current program position by highlighting the current line and marking it with a '>' marker. Breakpoints are indicated with two markers. The first marker indicates the breakpoint type: 'B' Breakpoint which was hit at least once. 'b' Breakpoint which was never hit. 'H' Hardware breakpoint which was hit at least once. 'h' Hardware breakpoint which was never hit. The second marker indicates whether the breakpoint is enabled or not: '+' Breakpoint is enabled. '-' Breakpoint is disabled. The source, assembly and register windows are updated when the current thread changes, when the frame changes, or when the program counter changes. These windows are not all visible at the same time. The command window is always visible. The others can be arranged in several layouts: * source only, * assembly only, * source and assembly, * source and registers, or * assembly and registers. A status line above the command window shows the following information: _target_ Indicates the current GDB target. (*note Specifying a Debugging Target: Targets.). _process_ Gives the current process or thread number. When no process is being debugged, this field is set to 'No process'. _function_ Gives the current function name for the selected frame. The name is demangled if demangling is turned on (*note Print Settings::). When there is no symbol corresponding to the current program counter, the string '??' is displayed. _line_ Indicates the current line number for the selected frame. When the current line number is not known, the string '??' is displayed. _pc_ Indicates the current program counter address.  File: gdb.info, Node: TUI Keys, Next: TUI Single Key Mode, Prev: TUI Overview, Up: TUI 25.2 TUI Key Bindings ===================== The TUI installs several key bindings in the readline keymaps (*note Command Line Editing::). The following key bindings are installed for both TUI mode and the GDB standard mode. 'C-x C-a' 'C-x a' 'C-x A' Enter or leave the TUI mode. When leaving the TUI mode, the curses window management stops and GDB operates using its standard mode, writing on the terminal directly. When reentering the TUI mode, control is given back to the curses windows. The screen is then refreshed. 'C-x 1' Use a TUI layout with only one window. The layout will either be 'source' or 'assembly'. When the TUI mode is not active, it will switch to the TUI mode. Think of this key binding as the Emacs 'C-x 1' binding. 'C-x 2' Use a TUI layout with at least two windows. When the current layout already has two windows, the next layout with two windows is used. When a new layout is chosen, one window will always be common to the previous layout and the new one. Think of it as the Emacs 'C-x 2' binding. 'C-x o' Change the active window. The TUI associates several key bindings (like scrolling and arrow keys) with the active window. This command gives the focus to the next TUI window. Think of it as the Emacs 'C-x o' binding. 'C-x s' Switch in and out of the TUI SingleKey mode that binds single keys to GDB commands (*note TUI Single Key Mode::). The following key bindings only work in the TUI mode: Scroll the active window one page up. Scroll the active window one page down. Scroll the active window one line up. Scroll the active window one line down. Scroll the active window one column left. Scroll the active window one column right. 'C-L' Refresh the screen. Because the arrow keys scroll the active window in the TUI mode, they are not available for their normal use by readline unless the command window has the focus. When another window is active, you must use other readline key bindings such as 'C-p', 'C-n', 'C-b' and 'C-f' to control the command window.  File: gdb.info, Node: TUI Single Key Mode, Next: TUI Commands, Prev: TUI Keys, Up: TUI 25.3 TUI Single Key Mode ======================== The TUI also provides a "SingleKey" mode, which binds several frequently used GDB commands to single keys. Type 'C-x s' to switch into this mode, where the following key bindings are used: 'c' continue 'd' down 'f' finish 'n' next 'q' exit the SingleKey mode. 'r' run 's' step 'u' up 'v' info locals 'w' where Other keys temporarily switch to the GDB command prompt. The key that was pressed is inserted in the editing buffer so that it is possible to type most GDB commands without interaction with the TUI SingleKey mode. Once the command is entered the TUI SingleKey mode is restored. The only way to permanently leave this mode is by typing 'q' or 'C-x s'.  File: gdb.info, Node: TUI Commands, Next: TUI Configuration, Prev: TUI Single Key Mode, Up: TUI 25.4 TUI-specific Commands ========================== The TUI has specific commands to control the text windows. These commands are always available, even when GDB is not in the TUI mode. When GDB is in the standard mode, most of these commands will automatically switch to the TUI mode. Note that if GDB's 'stdout' is not connected to a terminal, or GDB has been started with the machine interface interpreter (*note The GDB/MI Interface: GDB/MI.), most of these commands will fail with an error, because it would not be possible or desirable to enable curses window management. 'tui enable' Activate TUI mode. The last active TUI window layout will be used if TUI mode has prevsiouly been used in the current debugging session, otherwise a default layout is used. 'tui disable' Disable TUI mode, returning to the console interpreter. 'info win' List and give the size of all displayed windows. 'layout NAME' Changes which TUI windows are displayed. In each layout the command window is always displayed, the NAME parameter controls which additional windows are displayed, and can be any of the following: 'next' Display the next layout. 'prev' Display the previous layout. 'src' Display the source and command windows. 'asm' Display the assembly and command windows. 'split' Display the source, assembly, and command windows. 'regs' When in 'src' layout display the register, source, and command windows. When in 'asm' or 'split' layout display the register, assembler, and command windows. 'focus NAME' Changes which TUI window is currently active for scrolling. The NAME parameter can be any of the following: 'next' Make the next window active for scrolling. 'prev' Make the previous window active for scrolling. 'src' Make the source window active for scrolling. 'asm' Make the assembly window active for scrolling. 'regs' Make the register window active for scrolling. 'cmd' Make the command window active for scrolling. 'refresh' Refresh the screen. This is similar to typing 'C-L'. 'tui reg GROUP' Changes the register group displayed in the tui register window to GROUP. If the register window is not currently displayed this command will cause the register window to be displayed. The list of register groups, as well as their order is target specific. The following groups are available on most targets: 'next' Repeatedly selecting this group will cause the display to cycle through all of the available register groups. 'prev' Repeatedly selecting this group will cause the display to cycle through all of the available register groups in the reverse order to NEXT. 'general' Display the general registers. 'float' Display the floating point registers. 'system' Display the system registers. 'vector' Display the vector registers. 'all' Display all registers. 'update' Update the source window and the current execution point. 'winheight NAME +COUNT' 'winheight NAME -COUNT' Change the height of the window NAME by COUNT lines. Positive counts increase the height, while negative counts decrease it. The NAME parameter can be one of 'src' (the source window), 'cmd' (the command window), 'asm' (the disassembly window), or 'regs' (the register display window). 'tabset NCHARS' Set the width of tab stops to be NCHARS characters. This setting affects the display of TAB characters in the source and assembly windows.  File: gdb.info, Node: TUI Configuration, Prev: TUI Commands, Up: TUI 25.5 TUI Configuration Variables ================================ Several configuration variables control the appearance of TUI windows. 'set tui border-kind KIND' Select the border appearance for the source, assembly and register windows. The possible values are the following: 'space' Use a space character to draw the border. 'ascii' Use ASCII characters '+', '-' and '|' to draw the border. 'acs' Use the Alternate Character Set to draw the border. The border is drawn using character line graphics if the terminal supports them. 'set tui border-mode MODE' 'set tui active-border-mode MODE' Select the display attributes for the borders of the inactive windows or the active window. The MODE can be one of the following: 'normal' Use normal attributes to display the border. 'standout' Use standout mode. 'reverse' Use reverse video mode. 'half' Use half bright mode. 'half-standout' Use half bright and standout mode. 'bold' Use extra bright or bold mode. 'bold-standout' Use extra bright or bold and standout mode.  File: gdb.info, Node: Emacs, Next: GDB/MI, Prev: TUI, Up: Top 26 Using GDB under GNU Emacs **************************** A special interface allows you to use GNU Emacs to view (and edit) the source files for the program you are debugging with GDB. To use this interface, use the command 'M-x gdb' in Emacs. Give the executable file you want to debug as an argument. This command starts GDB as a subprocess of Emacs, with input and output through a newly created Emacs buffer. Running GDB under Emacs can be just like running GDB normally except for two things: * All "terminal" input and output goes through an Emacs buffer, called the GUD buffer. This applies both to GDB commands and their output, and to the input and output done by the program you are debugging. This is useful because it means that you can copy the text of previous commands and input them again; you can even use parts of the output in this way. All the facilities of Emacs' Shell mode are available for interacting with your program. In particular, you can send signals the usual way--for example, 'C-c C-c' for an interrupt, 'C-c C-z' for a stop. * GDB displays source code through Emacs. Each time GDB displays a stack frame, Emacs automatically finds the source file for that frame and puts an arrow ('=>') at the left margin of the current line. Emacs uses a separate buffer for source display, and splits the screen to show both your GDB session and the source. Explicit GDB 'list' or search commands still produce output as usual, but you probably have no reason to use them from Emacs. We call this "text command mode". Emacs 22.1, and later, also uses a graphical mode, enabled by default, which provides further buffers that can control the execution and describe the state of your program. *Note (Emacs)GDB Graphical Interface::. If you specify an absolute file name when prompted for the 'M-x gdb' argument, then Emacs sets your current working directory to where your program resides. If you only specify the file name, then Emacs sets your current working directory to the directory associated with the previous buffer. In this case, GDB may find your program by searching your environment's 'PATH' variable, but on some operating systems it might not find the source. So, although the GDB input and output session proceeds normally, the auxiliary buffer does not display the current source and line of execution. The initial working directory of GDB is printed on the top line of the GUD buffer and this serves as a default for the commands that specify files for GDB to operate on. *Note Commands to Specify Files: Files. By default, 'M-x gdb' calls the program called 'gdb'. If you need to call GDB by a different name (for example, if you keep several configurations around, with different names) you can customize the Emacs variable 'gud-gdb-command-name' to run the one you want. In the GUD buffer, you can use these special Emacs commands in addition to the standard Shell mode commands: 'C-h m' Describe the features of Emacs' GUD Mode. 'C-c C-s' Execute to another source line, like the GDB 'step' command; also update the display window to show the current file and location. 'C-c C-n' Execute to next source line in this function, skipping all function calls, like the GDB 'next' command. Then update the display window to show the current file and location. 'C-c C-i' Execute one instruction, like the GDB 'stepi' command; update display window accordingly. 'C-c C-f' Execute until exit from the selected stack frame, like the GDB 'finish' command. 'C-c C-r' Continue execution of your program, like the GDB 'continue' command. 'C-c <' Go up the number of frames indicated by the numeric argument (*note Numeric Arguments: (Emacs)Arguments.), like the GDB 'up' command. 'C-c >' Go down the number of frames indicated by the numeric argument, like the GDB 'down' command. In any source file, the Emacs command 'C-x ' ('gud-break') tells GDB to set a breakpoint on the source line point is on. In text command mode, if you type 'M-x speedbar', Emacs displays a separate frame which shows a backtrace when the GUD buffer is current. Move point to any frame in the stack and type to make it become the current frame and display the associated source in the source buffer. Alternatively, click 'Mouse-2' to make the selected frame become the current one. In graphical mode, the speedbar displays watch expressions. If you accidentally delete the source-display buffer, an easy way to get it back is to type the command 'f' in the GDB buffer, to request a frame display; when you run under Emacs, this recreates the source buffer if necessary to show you the context of the current frame. The source files displayed in Emacs are in ordinary Emacs buffers which are visiting the source files in the usual way. You can edit the files with these buffers if you wish; but keep in mind that GDB communicates with Emacs in terms of line numbers. If you add or delete lines from the text, the line numbers that GDB knows cease to correspond properly with the code. A more detailed description of Emacs' interaction with GDB is given in the Emacs manual (*note (Emacs)Debuggers::).  File: gdb.info, Node: GDB/MI, Next: Annotations, Prev: Emacs, Up: Top 27 The GDB/MI Interface *********************** Function and Purpose ==================== GDB/MI is a line based machine oriented text interface to GDB and is activated by specifying using the '--interpreter' command line option (*note Mode Options::). It is specifically intended to support the development of systems which use the debugger as just one small component of a larger system. This chapter is a specification of the GDB/MI interface. It is written in the form of a reference manual. Note that GDB/MI is still under construction, so some of the features described below are incomplete and subject to change (*note GDB/MI Development and Front Ends: GDB/MI Development and Front Ends.). Notation and Terminology ======================== This chapter uses the following notation: * '|' separates two alternatives. * '[ SOMETHING ]' indicates that SOMETHING is optional: it may or may not be given. * '( GROUP )*' means that GROUP inside the parentheses may repeat zero or more times. * '( GROUP )+' means that GROUP inside the parentheses may repeat one or more times. * '"STRING"' means a literal STRING. * Menu: * GDB/MI General Design:: * GDB/MI Command Syntax:: * GDB/MI Compatibility with CLI:: * GDB/MI Development and Front Ends:: * GDB/MI Output Records:: * GDB/MI Simple Examples:: * GDB/MI Command Description Format:: * GDB/MI Breakpoint Commands:: * GDB/MI Catchpoint Commands:: * GDB/MI Program Context:: * GDB/MI Thread Commands:: * GDB/MI Ada Tasking Commands:: * GDB/MI Program Execution:: * GDB/MI Stack Manipulation:: * GDB/MI Variable Objects:: * GDB/MI Data Manipulation:: * GDB/MI Tracepoint Commands:: * GDB/MI Symbol Query:: * GDB/MI File Commands:: * GDB/MI Target Manipulation:: * GDB/MI File Transfer Commands:: * GDB/MI Ada Exceptions Commands:: * GDB/MI Support Commands:: * GDB/MI Miscellaneous Commands::  File: gdb.info, Node: GDB/MI General Design, Next: GDB/MI Command Syntax, Up: GDB/MI 27.1 GDB/MI General Design ========================== Interaction of a GDB/MI frontend with GDB involves three parts--commands sent to GDB, responses to those commands and notifications. Each command results in exactly one response, indicating either successful completion of the command, or an error. For the commands that do not resume the target, the response contains the requested information. For the commands that resume the target, the response only indicates whether the target was successfully resumed. Notifications is the mechanism for reporting changes in the state of the target, or in GDB state, that cannot conveniently be associated with a command and reported as part of that command response. The important examples of notifications are: * Exec notifications. These are used to report changes in target state--when a target is resumed, or stopped. It would not be feasible to include this information in response of resuming commands, because one resume commands can result in multiple events in different threads. Also, quite some time may pass before any event happens in the target, while a frontend needs to know whether the resuming command itself was successfully executed. * Console output, and status notifications. Console output notifications are used to report output of CLI commands, as well as diagnostics for other commands. Status notifications are used to report the progress of a long-running operation. Naturally, including this information in command response would mean no output is produced until the command is finished, which is undesirable. * General notifications. Commands may have various side effects on the GDB or target state beyond their official purpose. For example, a command may change the selected thread. Although such changes can be included in command response, using notification allows for more orthogonal frontend design. There's no guarantee that whenever an MI command reports an error, GDB or the target are in any specific state, and especially, the state is not reverted to the state before the MI command was processed. Therefore, whenever an MI command results in an error, we recommend that the frontend refreshes all the information shown in the user interface. * Menu: * Context management:: * Asynchronous and non-stop modes:: * Thread groups::  File: gdb.info, Node: Context management, Next: Asynchronous and non-stop modes, Up: GDB/MI General Design 27.1.1 Context management ------------------------- 27.1.1.1 Threads and Frames ........................... In most cases when GDB accesses the target, this access is done in context of a specific thread and frame (*note Frames::). Often, even when accessing global data, the target requires that a thread be specified. The CLI interface maintains the selected thread and frame, and supplies them to target on each command. This is convenient, because a command line user would not want to specify that information explicitly on each command, and because user interacts with GDB via a single terminal, so no confusion is possible as to what thread and frame are the current ones. In the case of MI, the concept of selected thread and frame is less useful. First, a frontend can easily remember this information itself. Second, a graphical frontend can have more than one window, each one used for debugging a different thread, and the frontend might want to access additional threads for internal purposes. This increases the risk that by relying on implicitly selected thread, the frontend may be operating on a wrong one. Therefore, each MI command should explicitly specify which thread and frame to operate on. To make it possible, each MI command accepts the '--thread' and '--frame' options, the value to each is GDB global identifier for thread and frame to operate on. Usually, each top-level window in a frontend allows the user to select a thread and a frame, and remembers the user selection for further operations. However, in some cases GDB may suggest that the current thread or frame be changed. For example, when stopping on a breakpoint it is reasonable to switch to the thread where breakpoint is hit. For another example, if the user issues the CLI 'thread' or 'frame' commands via the frontend, it is desirable to change the frontend's selection to the one specified by user. GDB communicates the suggestion to change current thread and frame using the '=thread-selected' notification. Note that historically, MI shares the selected thread with CLI, so frontends used the '-thread-select' to execute commands in the right context. However, getting this to work right is cumbersome. The simplest way is for frontend to emit '-thread-select' command before every command. This doubles the number of commands that need to be sent. The alternative approach is to suppress '-thread-select' if the selected thread in GDB is supposed to be identical to the thread the frontend wants to operate on. However, getting this optimization right can be tricky. In particular, if the frontend sends several commands to GDB, and one of the commands changes the selected thread, then the behaviour of subsequent commands will change. So, a frontend should either wait for response from such problematic commands, or explicitly add '-thread-select' for all subsequent commands. No frontend is known to do this exactly right, so it is suggested to just always pass the '--thread' and '--frame' options. 27.1.1.2 Language ................. The execution of several commands depends on which language is selected. By default, the current language (*note show language::) is used. But for commands known to be language-sensitive, it is recommended to use the '--language' option. This option takes one argument, which is the name of the language to use while executing the command. For instance: -data-evaluate-expression --language c "sizeof (void*)" ^done,value="4" (gdb) The valid language names are the same names accepted by the 'set language' command (*note Manually::), excluding 'auto', 'local' or 'unknown'.  File: gdb.info, Node: Asynchronous and non-stop modes, Next: Thread groups, Prev: Context management, Up: GDB/MI General Design 27.1.2 Asynchronous command execution and non-stop mode ------------------------------------------------------- On some targets, GDB is capable of processing MI commands even while the target is running. This is called "asynchronous command execution" (*note Background Execution::). The frontend may specify a preferrence for asynchronous execution using the '-gdb-set mi-async 1' command, which should be emitted before either running the executable or attaching to the target. After the frontend has started the executable or attached to the target, it can find if asynchronous execution is enabled using the '-list-target-features' command. '-gdb-set mi-async on' '-gdb-set mi-async off' Set whether MI is in asynchronous mode. When 'off', which is the default, MI execution commands (e.g., '-exec-continue') are foreground commands, and GDB waits for the program to stop before processing further commands. When 'on', MI execution commands are background execution commands (e.g., '-exec-continue' becomes the equivalent of the 'c&' CLI command), and so GDB is capable of processing MI commands even while the target is running. '-gdb-show mi-async' Show whether MI asynchronous mode is enabled. Note: In GDB version 7.7 and earlier, this option was called 'target-async' instead of 'mi-async', and it had the effect of both putting MI in asynchronous mode and making CLI background commands possible. CLI background commands are now always possible "out of the box" if the target supports them. The old spelling is kept as a deprecated alias for backwards compatibility. Even if GDB can accept a command while target is running, many commands that access the target do not work when the target is running. Therefore, asynchronous command execution is most useful when combined with non-stop mode (*note Non-Stop Mode::). Then, it is possible to examine the state of one thread, while other threads are running. When a given thread is running, MI commands that try to access the target in the context of that thread may not work, or may work only on some targets. In particular, commands that try to operate on thread's stack will not work, on any target. Commands that read memory, or modify breakpoints, may work or not work, depending on the target. Note that even commands that operate on global state, such as 'print', 'set', and breakpoint commands, still access the target in the context of a specific thread, so frontend should try to find a stopped thread and perform the operation on that thread (using the '--thread' option). Which commands will work in the context of a running thread is highly target dependent. However, the two commands '-exec-interrupt', to stop a thread, and '-thread-info', to find the state of a thread, will always work.  File: gdb.info, Node: Thread groups, Prev: Asynchronous and non-stop modes, Up: GDB/MI General Design 27.1.3 Thread groups -------------------- GDB may be used to debug several processes at the same time. On some platfroms, GDB may support debugging of several hardware systems, each one having several cores with several different processes running on each core. This section describes the MI mechanism to support such debugging scenarios. The key observation is that regardless of the structure of the target, MI can have a global list of threads, because most commands that accept the '--thread' option do not need to know what process that thread belongs to. Therefore, it is not necessary to introduce neither additional '--process' option, nor an notion of the current process in the MI interface. The only strictly new feature that is required is the ability to find how the threads are grouped into processes. To allow the user to discover such grouping, and to support arbitrary hierarchy of machines/cores/processes, MI introduces the concept of a "thread group". Thread group is a collection of threads and other thread groups. A thread group always has a string identifier, a type, and may have additional attributes specific to the type. A new command, '-list-thread-groups', returns the list of top-level thread groups, which correspond to processes that GDB is debugging at the moment. By passing an identifier of a thread group to the '-list-thread-groups' command, it is possible to obtain the members of specific thread group. To allow the user to easily discover processes, and other objects, he wishes to debug, a concept of "available thread group" is introduced. Available thread group is an thread group that GDB is not debugging, but that can be attached to, using the '-target-attach' command. The list of available top-level thread groups can be obtained using '-list-thread-groups --available'. In general, the content of a thread group may be only retrieved only after attaching to that thread group. Thread groups are related to inferiors (*note Inferiors and Programs::). Each inferior corresponds to a thread group of a special type 'process', and some additional operations are permitted on such thread groups.  File: gdb.info, Node: GDB/MI Command Syntax, Next: GDB/MI Compatibility with CLI, Prev: GDB/MI General Design, Up: GDB/MI 27.2 GDB/MI Command Syntax ========================== * Menu: * GDB/MI Input Syntax:: * GDB/MI Output Syntax::  File: gdb.info, Node: GDB/MI Input Syntax, Next: GDB/MI Output Syntax, Up: GDB/MI Command Syntax 27.2.1 GDB/MI Input Syntax -------------------------- 'COMMAND ==>' 'CLI-COMMAND | MI-COMMAND' 'CLI-COMMAND ==>' '[ TOKEN ] CLI-COMMAND NL', where CLI-COMMAND is any existing GDB CLI command. 'MI-COMMAND ==>' '[ TOKEN ] "-" OPERATION ( " " OPTION )* [ " --" ] ( " " PARAMETER )* NL' 'TOKEN ==>' "any sequence of digits" 'OPTION ==>' '"-" PARAMETER [ " " PARAMETER ]' 'PARAMETER ==>' 'NON-BLANK-SEQUENCE | C-STRING' 'OPERATION ==>' _any of the operations described in this chapter_ 'NON-BLANK-SEQUENCE ==>' _anything, provided it doesn't contain special characters such as "-", NL, """ and of course " "_ 'C-STRING ==>' '""" SEVEN-BIT-ISO-C-STRING-CONTENT """' 'NL ==>' 'CR | CR-LF' Notes: * The CLI commands are still handled by the MI interpreter; their output is described below. * The 'TOKEN', when present, is passed back when the command finishes. * Some MI commands accept optional arguments as part of the parameter list. Each option is identified by a leading '-' (dash) and may be followed by an optional argument parameter. Options occur first in the parameter list and can be delimited from normal parameters using '--' (this is useful when some parameters begin with a dash). Pragmatics: * We want easy access to the existing CLI syntax (for debugging). * We want it to be easy to spot a MI operation.  File: gdb.info, Node: GDB/MI Output Syntax, Prev: GDB/MI Input Syntax, Up: GDB/MI Command Syntax 27.2.2 GDB/MI Output Syntax --------------------------- The output from GDB/MI consists of zero or more out-of-band records followed, optionally, by a single result record. This result record is for the most recent command. The sequence of output records is terminated by '(gdb)'. If an input command was prefixed with a 'TOKEN' then the corresponding output for that command will also be prefixed by that same TOKEN. 'OUTPUT ==>' '( OUT-OF-BAND-RECORD )* [ RESULT-RECORD ] "(gdb)" NL' 'RESULT-RECORD ==>' ' [ TOKEN ] "^" RESULT-CLASS ( "," RESULT )* NL' 'OUT-OF-BAND-RECORD ==>' 'ASYNC-RECORD | STREAM-RECORD' 'ASYNC-RECORD ==>' 'EXEC-ASYNC-OUTPUT | STATUS-ASYNC-OUTPUT | NOTIFY-ASYNC-OUTPUT' 'EXEC-ASYNC-OUTPUT ==>' '[ TOKEN ] "*" ASYNC-OUTPUT NL' 'STATUS-ASYNC-OUTPUT ==>' '[ TOKEN ] "+" ASYNC-OUTPUT NL' 'NOTIFY-ASYNC-OUTPUT ==>' '[ TOKEN ] "=" ASYNC-OUTPUT NL' 'ASYNC-OUTPUT ==>' 'ASYNC-CLASS ( "," RESULT )*' 'RESULT-CLASS ==>' '"done" | "running" | "connected" | "error" | "exit"' 'ASYNC-CLASS ==>' '"stopped" | OTHERS' (where OTHERS will be added depending on the needs--this is still in development). 'RESULT ==>' ' VARIABLE "=" VALUE' 'VARIABLE ==>' ' STRING ' 'VALUE ==>' ' CONST | TUPLE | LIST ' 'CONST ==>' 'C-STRING' 'TUPLE ==>' ' "{}" | "{" RESULT ( "," RESULT )* "}" ' 'LIST ==>' ' "[]" | "[" VALUE ( "," VALUE )* "]" | "[" RESULT ( "," RESULT )* "]" ' 'STREAM-RECORD ==>' 'CONSOLE-STREAM-OUTPUT | TARGET-STREAM-OUTPUT | LOG-STREAM-OUTPUT' 'CONSOLE-STREAM-OUTPUT ==>' '"~" C-STRING NL' 'TARGET-STREAM-OUTPUT ==>' '"@" C-STRING NL' 'LOG-STREAM-OUTPUT ==>' '"&" C-STRING NL' 'NL ==>' 'CR | CR-LF' 'TOKEN ==>' _any sequence of digits_. Notes: * All output sequences end in a single line containing a period. * The 'TOKEN' is from the corresponding request. Note that for all async output, while the token is allowed by the grammar and may be output by future versions of GDB for select async output messages, it is generally omitted. Frontends should treat all async output as reporting general changes in the state of the target and there should be no need to associate async output to any prior command. * STATUS-ASYNC-OUTPUT contains on-going status information about the progress of a slow operation. It can be discarded. All status output is prefixed by '+'. * EXEC-ASYNC-OUTPUT contains asynchronous state change on the target (stopped, started, disappeared). All async output is prefixed by '*'. * NOTIFY-ASYNC-OUTPUT contains supplementary information that the client should handle (e.g., a new breakpoint information). All notify output is prefixed by '='. * CONSOLE-STREAM-OUTPUT is output that should be displayed as is in the console. It is the textual response to a CLI command. All the console output is prefixed by '~'. * TARGET-STREAM-OUTPUT is the output produced by the target program. All the target output is prefixed by '@'. * LOG-STREAM-OUTPUT is output text coming from GDB's internals, for instance messages that should be displayed as part of an error log. All the log output is prefixed by '&'. * New GDB/MI commands should only output LISTS containing VALUES. *Note GDB/MI Stream Records: GDB/MI Stream Records, for more details about the various output records.  File: gdb.info, Node: GDB/MI Compatibility with CLI, Next: GDB/MI Development and Front Ends, Prev: GDB/MI Command Syntax, Up: GDB/MI 27.3 GDB/MI Compatibility with CLI ================================== For the developers convenience CLI commands can be entered directly, but there may be some unexpected behaviour. For example, commands that query the user will behave as if the user replied yes, breakpoint command lists are not executed and some CLI commands, such as 'if', 'when' and 'define', prompt for further input with '>', which is not valid MI output. This feature may be removed at some stage in the future and it is recommended that front ends use the '-interpreter-exec' command (*note -interpreter-exec::).  File: gdb.info, Node: GDB/MI Development and Front Ends, Next: GDB/MI Output Records, Prev: GDB/MI Compatibility with CLI, Up: GDB/MI 27.4 GDB/MI Development and Front Ends ====================================== The application which takes the MI output and presents the state of the program being debugged to the user is called a "front end". Although GDB/MI is still incomplete, it is currently being used by a variety of front ends to GDB. This makes it difficult to introduce new functionality without breaking existing usage. This section tries to minimize the problems by describing how the protocol might change. Some changes in MI need not break a carefully designed front end, and for these the MI version will remain unchanged. The following is a list of changes that may occur within one level, so front ends should parse MI output in a way that can handle them: * New MI commands may be added. * New fields may be added to the output of any MI command. * The range of values for fields with specified values, e.g., 'in_scope' (*note -var-update::) may be extended. If the changes are likely to break front ends, the MI version level will be increased by one. This will allow the front end to parse the output according to the MI version. Apart from mi0, new versions of GDB will not support old versions of MI and it will be the responsibility of the front end to work with the new one. The best way to avoid unexpected changes in MI that might break your front end is to make your project known to GDB developers and follow development on and .  File: gdb.info, Node: GDB/MI Output Records, Next: GDB/MI Simple Examples, Prev: GDB/MI Development and Front Ends, Up: GDB/MI 27.5 GDB/MI Output Records ========================== * Menu: * GDB/MI Result Records:: * GDB/MI Stream Records:: * GDB/MI Async Records:: * GDB/MI Breakpoint Information:: * GDB/MI Frame Information:: * GDB/MI Thread Information:: * GDB/MI Ada Exception Information::  File: gdb.info, Node: GDB/MI Result Records, Next: GDB/MI Stream Records, Up: GDB/MI Output Records 27.5.1 GDB/MI Result Records ---------------------------- In addition to a number of out-of-band notifications, the response to a GDB/MI command includes one of the following result indications: '"^done" [ "," RESULTS ]' The synchronous operation was successful, 'RESULTS' are the return values. '"^running"' This result record is equivalent to '^done'. Historically, it was output instead of '^done' if the command has resumed the target. This behaviour is maintained for backward compatibility, but all frontends should treat '^done' and '^running' identically and rely on the '*running' output record to determine which threads are resumed. '"^connected"' GDB has connected to a remote target. '"^error" "," "msg=" C-STRING [ "," "code=" C-STRING ]' The operation failed. The 'msg=C-STRING' variable contains the corresponding error message. If present, the 'code=C-STRING' variable provides an error code on which consumers can rely on to detect the corresponding error condition. At present, only one error code is defined: '"undefined-command"' Indicates that the command causing the error does not exist. '"^exit"' GDB has terminated.  File: gdb.info, Node: GDB/MI Stream Records, Next: GDB/MI Async Records, Prev: GDB/MI Result Records, Up: GDB/MI Output Records 27.5.2 GDB/MI Stream Records ---------------------------- GDB internally maintains a number of output streams: the console, the target, and the log. The output intended for each of these streams is funneled through the GDB/MI interface using "stream records". Each stream record begins with a unique "prefix character" which identifies its stream (*note GDB/MI Output Syntax: GDB/MI Output Syntax.). In addition to the prefix, each stream record contains a 'STRING-OUTPUT'. This is either raw text (with an implicit new line) or a quoted C string (which does not contain an implicit newline). '"~" STRING-OUTPUT' The console output stream contains text that should be displayed in the CLI console window. It contains the textual responses to CLI commands. '"@" STRING-OUTPUT' The target output stream contains any textual output from the running target. This is only present when GDB's event loop is truly asynchronous, which is currently only the case for remote targets. '"&" STRING-OUTPUT' The log stream contains debugging messages being produced by GDB's internals.  File: gdb.info, Node: GDB/MI Async Records, Next: GDB/MI Breakpoint Information, Prev: GDB/MI Stream Records, Up: GDB/MI Output Records 27.5.3 GDB/MI Async Records --------------------------- "Async" records are used to notify the GDB/MI client of additional changes that have occurred. Those changes can either be a consequence of GDB/MI commands (e.g., a breakpoint modified) or a result of target activity (e.g., target stopped). The following is the list of possible async records: '*running,thread-id="THREAD"' The target is now running. The THREAD field can be the global thread ID of the the thread that is now running, and it can be 'all' if all threads are running. The frontend should assume that no interaction with a running thread is possible after this notification is produced. The frontend should not assume that this notification is output only once for any command. GDB may emit this notification several times, either for different threads, because it cannot resume all threads together, or even for a single thread, if the thread must be stepped though some code before letting it run freely. '*stopped,reason="REASON",thread-id="ID",stopped-threads="STOPPED",core="CORE"' The target has stopped. The REASON field can have one of the following values: 'breakpoint-hit' A breakpoint was reached. 'watchpoint-trigger' A watchpoint was triggered. 'read-watchpoint-trigger' A read watchpoint was triggered. 'access-watchpoint-trigger' An access watchpoint was triggered. 'function-finished' An -exec-finish or similar CLI command was accomplished. 'location-reached' An -exec-until or similar CLI command was accomplished. 'watchpoint-scope' A watchpoint has gone out of scope. 'end-stepping-range' An -exec-next, -exec-next-instruction, -exec-step, -exec-step-instruction or similar CLI command was accomplished. 'exited-signalled' The inferior exited because of a signal. 'exited' The inferior exited. 'exited-normally' The inferior exited normally. 'signal-received' A signal was received by the inferior. 'solib-event' The inferior has stopped due to a library being loaded or unloaded. This can happen when 'stop-on-solib-events' (*note Files::) is set or when a 'catch load' or 'catch unload' catchpoint is in use (*note Set Catchpoints::). 'fork' The inferior has forked. This is reported when 'catch fork' (*note Set Catchpoints::) has been used. 'vfork' The inferior has vforked. This is reported in when 'catch vfork' (*note Set Catchpoints::) has been used. 'syscall-entry' The inferior entered a system call. This is reported when 'catch syscall' (*note Set Catchpoints::) has been used. 'syscall-return' The inferior returned from a system call. This is reported when 'catch syscall' (*note Set Catchpoints::) has been used. 'exec' The inferior called 'exec'. This is reported when 'catch exec' (*note Set Catchpoints::) has been used. The ID field identifies the global thread ID of the thread that directly caused the stop - for example by hitting a breakpoint. Depending on whether all-stop mode is in effect (*note All-Stop Mode::), GDB may either stop all threads, or only the thread that directly triggered the stop. If all threads are stopped, the STOPPED field will have the value of '"all"'. Otherwise, the value of the STOPPED field will be a list of thread identifiers. Presently, this list will always include a single thread, but frontend should be prepared to see several threads in the list. The CORE field reports the processor core on which the stop event has happened. This field may be absent if such information is not available. '=thread-group-added,id="ID"' '=thread-group-removed,id="ID"' A thread group was either added or removed. The ID field contains the GDB identifier of the thread group. When a thread group is added, it generally might not be associated with a running process. When a thread group is removed, its id becomes invalid and cannot be used in any way. '=thread-group-started,id="ID",pid="PID"' A thread group became associated with a running program, either because the program was just started or the thread group was attached to a program. The ID field contains the GDB identifier of the thread group. The PID field contains process identifier, specific to the operating system. '=thread-group-exited,id="ID"[,exit-code="CODE"]' A thread group is no longer associated with a running program, either because the program has exited, or because it was detached from. The ID field contains the GDB identifier of the thread group. The CODE field is the exit code of the inferior; it exists only when the inferior exited with some code. '=thread-created,id="ID",group-id="GID"' '=thread-exited,id="ID",group-id="GID"' A thread either was created, or has exited. The ID field contains the global GDB identifier of the thread. The GID field identifies the thread group this thread belongs to. '=thread-selected,id="ID"[,frame="FRAME"]' Informs that the selected thread or frame were changed. This notification is not emitted as result of the '-thread-select' or '-stack-select-frame' commands, but is emitted whenever an MI command that is not documented to change the selected thread and frame actually changes them. In particular, invoking, directly or indirectly (via user-defined command), the CLI 'thread' or 'frame' commands, will generate this notification. Changing the thread or frame from another user interface (see *note Interpreters::) will also generate this notification. The FRAME field is only present if the newly selected thread is stopped. See *note GDB/MI Frame Information:: for the format of its value. We suggest that in response to this notification, front ends highlight the selected thread and cause subsequent commands to apply to that thread. '=library-loaded,...' Reports that a new library file was loaded by the program. This notification has 5 fields--ID, TARGET-NAME, HOST-NAME, SYMBOLS-LOADED and RANGES. The ID field is an opaque identifier of the library. For remote debugging case, TARGET-NAME and HOST-NAME fields give the name of the library file on the target, and on the host respectively. For native debugging, both those fields have the same value. The SYMBOLS-LOADED field is emitted only for backward compatibility and should not be relied on to convey any useful information. The THREAD-GROUP field, if present, specifies the id of the thread group in whose context the library was loaded. If the field is absent, it means the library was loaded in the context of all present thread groups. The RANGES field specifies the ranges of addresses belonging to this library. '=library-unloaded,...' Reports that a library was unloaded by the program. This notification has 3 fields--ID, TARGET-NAME and HOST-NAME with the same meaning as for the '=library-loaded' notification. The THREAD-GROUP field, if present, specifies the id of the thread group in whose context the library was unloaded. If the field is absent, it means the library was unloaded in the context of all present thread groups. '=traceframe-changed,num=TFNUM,tracepoint=TPNUM' '=traceframe-changed,end' Reports that the trace frame was changed and its new number is TFNUM. The number of the tracepoint associated with this trace frame is TPNUM. '=tsv-created,name=NAME,initial=INITIAL' Reports that the new trace state variable NAME is created with initial value INITIAL. '=tsv-deleted,name=NAME' '=tsv-deleted' Reports that the trace state variable NAME is deleted or all trace state variables are deleted. '=tsv-modified,name=NAME,initial=INITIAL[,current=CURRENT]' Reports that the trace state variable NAME is modified with the initial value INITIAL. The current value CURRENT of trace state variable is optional and is reported if the current value of trace state variable is known. '=breakpoint-created,bkpt={...}' '=breakpoint-modified,bkpt={...}' '=breakpoint-deleted,id=NUMBER' Reports that a breakpoint was created, modified, or deleted, respectively. Only user-visible breakpoints are reported to the MI user. The BKPT argument is of the same form as returned by the various breakpoint commands; *Note GDB/MI Breakpoint Commands::. The NUMBER is the ordinal number of the breakpoint. Note that if a breakpoint is emitted in the result record of a command, then it will not also be emitted in an async record. '=record-started,thread-group="ID",method="METHOD"[,format="FORMAT"]' '=record-stopped,thread-group="ID"' Execution log recording was either started or stopped on an inferior. The ID is the GDB identifier of the thread group corresponding to the affected inferior. The METHOD field indicates the method used to record execution. If the method in use supports multiple recording formats, FORMAT will be present and contain the currently used format. *Note Process Record and Replay::, for existing method and format values. '=cmd-param-changed,param=PARAM,value=VALUE' Reports that a parameter of the command 'set PARAM' is changed to VALUE. In the multi-word 'set' command, the PARAM is the whole parameter list to 'set' command. For example, In command 'set check type on', PARAM is 'check type' and VALUE is 'on'. '=memory-changed,thread-group=ID,addr=ADDR,len=LEN[,type="code"]' Reports that bytes from ADDR to DATA + LEN were written in an inferior. The ID is the identifier of the thread group corresponding to the affected inferior. The optional 'type="code"' part is reported if the memory written to holds executable code.  File: gdb.info, Node: GDB/MI Breakpoint Information, Next: GDB/MI Frame Information, Prev: GDB/MI Async Records, Up: GDB/MI Output Records 27.5.4 GDB/MI Breakpoint Information ------------------------------------ When GDB reports information about a breakpoint, a tracepoint, a watchpoint, or a catchpoint, it uses a tuple with the following fields: 'number' The breakpoint number. For a breakpoint that represents one location of a multi-location breakpoint, this will be a dotted pair, like '1.2'. 'type' The type of the breakpoint. For ordinary breakpoints this will be 'breakpoint', but many values are possible. 'catch-type' If the type of the breakpoint is 'catchpoint', then this indicates the exact type of catchpoint. 'disp' This is the breakpoint disposition--either 'del', meaning that the breakpoint will be deleted at the next stop, or 'keep', meaning that the breakpoint will not be deleted. 'enabled' This indicates whether the breakpoint is enabled, in which case the value is 'y', or disabled, in which case the value is 'n'. Note that this is not the same as the field 'enable'. 'addr' The address of the breakpoint. This may be a hexidecimal number, giving the address; or the string '', for a pending breakpoint; or the string '', for a breakpoint with multiple locations. This field will not be present if no address can be determined. For example, a watchpoint does not have an address. 'func' If known, the function in which the breakpoint appears. If not known, this field is not present. 'filename' The name of the source file which contains this function, if known. If not known, this field is not present. 'fullname' The full file name of the source file which contains this function, if known. If not known, this field is not present. 'line' The line number at which this breakpoint appears, if known. If not known, this field is not present. 'at' If the source file is not known, this field may be provided. If provided, this holds the address of the breakpoint, possibly followed by a symbol name. 'pending' If this breakpoint is pending, this field is present and holds the text used to set the breakpoint, as entered by the user. 'evaluated-by' Where this breakpoint's condition is evaluated, either 'host' or 'target'. 'thread' If this is a thread-specific breakpoint, then this identifies the thread in which the breakpoint can trigger. 'task' If this breakpoint is restricted to a particular Ada task, then this field will hold the task identifier. 'cond' If the breakpoint is conditional, this is the condition expression. 'ignore' The ignore count of the breakpoint. 'enable' The enable count of the breakpoint. 'traceframe-usage' FIXME. 'static-tracepoint-marker-string-id' For a static tracepoint, the name of the static tracepoint marker. 'mask' For a masked watchpoint, this is the mask. 'pass' A tracepoint's pass count. 'original-location' The location of the breakpoint as originally specified by the user. This field is optional. 'times' The number of times the breakpoint has been hit. 'installed' This field is only given for tracepoints. This is either 'y', meaning that the tracepoint is installed, or 'n', meaning that it is not. 'what' Some extra data, the exact contents of which are type-dependent. For example, here is what the output of '-break-insert' (*note GDB/MI Breakpoint Commands::) might be: -> -break-insert main <- ^done,bkpt={number="1",type="breakpoint",disp="keep", enabled="y",addr="0x08048564",func="main",file="myprog.c", fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"], times="0"} <- (gdb)  File: gdb.info, Node: GDB/MI Frame Information, Next: GDB/MI Thread Information, Prev: GDB/MI Breakpoint Information, Up: GDB/MI Output Records 27.5.5 GDB/MI Frame Information ------------------------------- Response from many MI commands includes an information about stack frame. This information is a tuple that may have the following fields: 'level' The level of the stack frame. The innermost frame has the level of zero. This field is always present. 'func' The name of the function corresponding to the frame. This field may be absent if GDB is unable to determine the function name. 'addr' The code address for the frame. This field is always present. 'file' The name of the source files that correspond to the frame's code address. This field may be absent. 'line' The source line corresponding to the frames' code address. This field may be absent. 'from' The name of the binary file (either executable or shared library) the corresponds to the frame's code address. This field may be absent.  File: gdb.info, Node: GDB/MI Thread Information, Next: GDB/MI Ada Exception Information, Prev: GDB/MI Frame Information, Up: GDB/MI Output Records 27.5.6 GDB/MI Thread Information -------------------------------- Whenever GDB has to report an information about a thread, it uses a tuple with the following fields: 'id' The global numeric id assigned to the thread by GDB. This field is always present. 'target-id' Target-specific string identifying the thread. This field is always present. 'details' Additional information about the thread provided by the target. It is supposed to be human-readable and not interpreted by the frontend. This field is optional. 'state' Either 'stopped' or 'running', depending on whether the thread is presently running. This field is always present. 'core' The value of this field is an integer number of the processor core the thread was last seen on. This field is optional.  File: gdb.info, Node: GDB/MI Ada Exception Information, Prev: GDB/MI Thread Information, Up: GDB/MI Output Records 27.5.7 GDB/MI Ada Exception Information --------------------------------------- Whenever a '*stopped' record is emitted because the program stopped after hitting an exception catchpoint (*note Set Catchpoints::), GDB provides the name of the exception that was raised via the 'exception-name' field.  File: gdb.info, Node: GDB/MI Simple Examples, Next: GDB/MI Command Description Format, Prev: GDB/MI Output Records, Up: GDB/MI 27.6 Simple Examples of GDB/MI Interaction ========================================== This subsection presents several simple examples of interaction using the GDB/MI interface. In these examples, '->' means that the following line is passed to GDB/MI as input, while '<-' means the output received from GDB/MI. Note the line breaks shown in the examples are here only for readability, they don't appear in the real output. Setting a Breakpoint -------------------- Setting a breakpoint generates synchronous output which contains detailed information of the breakpoint. -> -break-insert main <- ^done,bkpt={number="1",type="breakpoint",disp="keep", enabled="y",addr="0x08048564",func="main",file="myprog.c", fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"], times="0"} <- (gdb) Program Execution ----------------- Program execution generates asynchronous records and MI gives the reason that execution stopped. -> -exec-run <- ^running <- (gdb) <- *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0", frame={addr="0x08048564",func="main", args=[{name="argc",value="1"},{name="argv",value="0xbfc4d4d4"}], file="myprog.c",fullname="/home/nickrob/myprog.c",line="68"} <- (gdb) -> -exec-continue <- ^running <- (gdb) <- *stopped,reason="exited-normally" <- (gdb) Quitting GDB ------------ Quitting GDB just prints the result class '^exit'. -> (gdb) <- -gdb-exit <- ^exit Please note that '^exit' is printed immediately, but it might take some time for GDB to actually exit. During that time, GDB performs necessary cleanups, including killing programs being debugged or disconnecting from debug hardware, so the frontend should wait till GDB exits and should only forcibly kill GDB if it fails to exit in reasonable time. A Bad Command ------------- Here's what happens if you pass a non-existent command: -> -rubbish <- ^error,msg="Undefined MI command: rubbish" <- (gdb)  File: gdb.info, Node: GDB/MI Command Description Format, Next: GDB/MI Breakpoint Commands, Prev: GDB/MI Simple Examples, Up: GDB/MI 27.7 GDB/MI Command Description Format ====================================== The remaining sections describe blocks of commands. Each block of commands is laid out in a fashion similar to this section. Motivation ---------- The motivation for this collection of commands. Introduction ------------ A brief introduction to this collection of commands as a whole. Commands -------- For each command in the block, the following is described: Synopsis ........ -command ARGS... Result ...... GDB Command ........... The corresponding GDB CLI command(s), if any. Example ....... Example(s) formatted for readability. Some of the described commands have not been implemented yet and these are labeled N.A. (not available).  File: gdb.info, Node: GDB/MI Breakpoint Commands, Next: GDB/MI Catchpoint Commands, Prev: GDB/MI Command Description Format, Up: GDB/MI 27.8 GDB/MI Breakpoint Commands =============================== This section documents GDB/MI commands for manipulating breakpoints. The '-break-after' Command -------------------------- Synopsis ........ -break-after NUMBER COUNT The breakpoint number NUMBER is not in effect until it has been hit COUNT times. To see how this is reflected in the output of the '-break-list' command, see the description of the '-break-list' command below. GDB Command ........... The corresponding GDB command is 'ignore'. Example ....... (gdb) -break-insert main ^done,bkpt={number="1",type="breakpoint",disp="keep", enabled="y",addr="0x000100d0",func="main",file="hello.c", fullname="/home/foo/hello.c",line="5",thread-groups=["i1"], times="0"} (gdb) -break-after 1 3 ~ ^done (gdb) -break-list ^done,BreakpointTable={nr_rows="1",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", line="5",thread-groups=["i1"],times="0",ignore="3"}]} (gdb) The '-break-commands' Command ----------------------------- Synopsis ........ -break-commands NUMBER [ COMMAND1 ... COMMANDN ] Specifies the CLI commands that should be executed when breakpoint NUMBER is hit. The parameters COMMAND1 to COMMANDN are the commands. If no command is specified, any previously-set commands are cleared. *Note Break Commands::. Typical use of this functionality is tracing a program, that is, printing of values of some variables whenever breakpoint is hit and then continuing. GDB Command ........... The corresponding GDB command is 'commands'. Example ....... (gdb) -break-insert main ^done,bkpt={number="1",type="breakpoint",disp="keep", enabled="y",addr="0x000100d0",func="main",file="hello.c", fullname="/home/foo/hello.c",line="5",thread-groups=["i1"], times="0"} (gdb) -break-commands 1 "print v" "continue" ^done (gdb) The '-break-condition' Command ------------------------------ Synopsis ........ -break-condition NUMBER EXPR Breakpoint NUMBER will stop the program only if the condition in EXPR is true. The condition becomes part of the '-break-list' output (see the description of the '-break-list' command below). GDB Command ........... The corresponding GDB command is 'condition'. Example ....... (gdb) -break-condition 1 1 ^done (gdb) -break-list ^done,BreakpointTable={nr_rows="1",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", line="5",cond="1",thread-groups=["i1"],times="0",ignore="3"}]} (gdb) The '-break-delete' Command --------------------------- Synopsis ........ -break-delete ( BREAKPOINT )+ Delete the breakpoint(s) whose number(s) are specified in the argument list. This is obviously reflected in the breakpoint list. GDB Command ........... The corresponding GDB command is 'delete'. Example ....... (gdb) -break-delete 1 ^done (gdb) -break-list ^done,BreakpointTable={nr_rows="0",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[]} (gdb) The '-break-disable' Command ---------------------------- Synopsis ........ -break-disable ( BREAKPOINT )+ Disable the named BREAKPOINT(s). The field 'enabled' in the break list is now set to 'n' for the named BREAKPOINT(s). GDB Command ........... The corresponding GDB command is 'disable'. Example ....... (gdb) -break-disable 2 ^done (gdb) -break-list ^done,BreakpointTable={nr_rows="1",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="n", addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", line="5",thread-groups=["i1"],times="0"}]} (gdb) The '-break-enable' Command --------------------------- Synopsis ........ -break-enable ( BREAKPOINT )+ Enable (previously disabled) BREAKPOINT(s). GDB Command ........... The corresponding GDB command is 'enable'. Example ....... (gdb) -break-enable 2 ^done (gdb) -break-list ^done,BreakpointTable={nr_rows="1",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="y", addr="0x000100d0",func="main",file="hello.c",fullname="/home/foo/hello.c", line="5",thread-groups=["i1"],times="0"}]} (gdb) The '-break-info' Command ------------------------- Synopsis ........ -break-info BREAKPOINT Get information about a single breakpoint. The result is a table of breakpoints. *Note GDB/MI Breakpoint Information::, for details on the format of each breakpoint in the table. GDB Command ........... The corresponding GDB command is 'info break BREAKPOINT'. Example ....... N.A. The '-break-insert' Command --------------------------- Synopsis ........ -break-insert [ -t ] [ -h ] [ -f ] [ -d ] [ -a ] [ -c CONDITION ] [ -i IGNORE-COUNT ] [ -p THREAD-ID ] [ LOCATION ] If specified, LOCATION, can be one of: LINESPEC LOCATION A linespec location. *Note Linespec Locations::. EXPLICIT LOCATION An explicit location. GDB/MI explicit locations are analogous to the CLI's explicit locations using the option names listed below. *Note Explicit Locations::. '--source FILENAME' The source file name of the location. This option requires the use of either '--function' or '--line'. '--function FUNCTION' The name of a function or method. '--label LABEL' The name of a label. '--line LINEOFFSET' An absolute or relative line offset from the start of the location. ADDRESS LOCATION An address location, *ADDRESS. *Note Address Locations::. The possible optional parameters of this command are: '-t' Insert a temporary breakpoint. '-h' Insert a hardware breakpoint. '-f' If LOCATION cannot be parsed (for example if it refers to unknown files or functions), create a pending breakpoint. Without this flag, GDB will report an error, and won't create a breakpoint, if LOCATION cannot be parsed. '-d' Create a disabled breakpoint. '-a' Create a tracepoint. *Note Tracepoints::. When this parameter is used together with '-h', a fast tracepoint is created. '-c CONDITION' Make the breakpoint conditional on CONDITION. '-i IGNORE-COUNT' Initialize the IGNORE-COUNT. '-p THREAD-ID' Restrict the breakpoint to the thread with the specified global THREAD-ID. Result ...... *Note GDB/MI Breakpoint Information::, for details on the format of the resulting breakpoint. Note: this format is open to change. GDB Command ........... The corresponding GDB commands are 'break', 'tbreak', 'hbreak', and 'thbreak'. Example ....... (gdb) -break-insert main ^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c", fullname="/home/foo/recursive2.c,line="4",thread-groups=["i1"], times="0"} (gdb) -break-insert -t foo ^done,bkpt={number="2",addr="0x00010774",file="recursive2.c", fullname="/home/foo/recursive2.c,line="11",thread-groups=["i1"], times="0"} (gdb) -break-list ^done,BreakpointTable={nr_rows="2",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x0001072c", func="main",file="recursive2.c", fullname="/home/foo/recursive2.c,"line="4",thread-groups=["i1"], times="0"}, bkpt={number="2",type="breakpoint",disp="del",enabled="y", addr="0x00010774",func="foo",file="recursive2.c", fullname="/home/foo/recursive2.c",line="11",thread-groups=["i1"], times="0"}]} (gdb) The '-dprintf-insert' Command ----------------------------- Synopsis ........ -dprintf-insert [ -t ] [ -f ] [ -d ] [ -c CONDITION ] [ -i IGNORE-COUNT ] [ -p THREAD-ID ] [ LOCATION ] [ FORMAT ] [ ARGUMENT ] If supplied, LOCATION may be specified the same way as for the '-break-insert' command. *Note -break-insert::. The possible optional parameters of this command are: '-t' Insert a temporary breakpoint. '-f' If LOCATION cannot be parsed (for example, if it refers to unknown files or functions), create a pending breakpoint. Without this flag, GDB will report an error, and won't create a breakpoint, if LOCATION cannot be parsed. '-d' Create a disabled breakpoint. '-c CONDITION' Make the breakpoint conditional on CONDITION. '-i IGNORE-COUNT' Set the ignore count of the breakpoint (*note ignore count: Conditions.) to IGNORE-COUNT. '-p THREAD-ID' Restrict the breakpoint to the thread with the specified global THREAD-ID. Result ...... *Note GDB/MI Breakpoint Information::, for details on the format of the resulting breakpoint. GDB Command ........... The corresponding GDB command is 'dprintf'. Example ....... (gdb) 4-dprintf-insert foo "At foo entry\n" 4^done,bkpt={number="1",type="dprintf",disp="keep",enabled="y", addr="0x000000000040061b",func="foo",file="mi-dprintf.c", fullname="mi-dprintf.c",line="25",thread-groups=["i1"], times="0",script={"printf \"At foo entry\\n\"","continue"}, original-location="foo"} (gdb) 5-dprintf-insert 26 "arg=%d, g=%d\n" arg g 5^done,bkpt={number="2",type="dprintf",disp="keep",enabled="y", addr="0x000000000040062a",func="foo",file="mi-dprintf.c", fullname="mi-dprintf.c",line="26",thread-groups=["i1"], times="0",script={"printf \"arg=%d, g=%d\\n\", arg, g","continue"}, original-location="mi-dprintf.c:26"} (gdb) The '-break-list' Command ------------------------- Synopsis ........ -break-list Displays the list of inserted breakpoints, showing the following fields: 'Number' number of the breakpoint 'Type' type of the breakpoint: 'breakpoint' or 'watchpoint' 'Disposition' should the breakpoint be deleted or disabled when it is hit: 'keep' or 'nokeep' 'Enabled' is the breakpoint enabled or no: 'y' or 'n' 'Address' memory location at which the breakpoint is set 'What' logical location of the breakpoint, expressed by function name, file name, line number 'Thread-groups' list of thread groups to which this breakpoint applies 'Times' number of times the breakpoint has been hit If there are no breakpoints or watchpoints, the 'BreakpointTable' 'body' field is an empty list. GDB Command ........... The corresponding GDB command is 'info break'. Example ....... (gdb) -break-list ^done,BreakpointTable={nr_rows="2",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x000100d0",func="main",file="hello.c",line="5",thread-groups=["i1"], times="0"}, bkpt={number="2",type="breakpoint",disp="keep",enabled="y", addr="0x00010114",func="foo",file="hello.c",fullname="/home/foo/hello.c", line="13",thread-groups=["i1"],times="0"}]} (gdb) Here's an example of the result when there are no breakpoints: (gdb) -break-list ^done,BreakpointTable={nr_rows="0",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[]} (gdb) The '-break-passcount' Command ------------------------------ Synopsis ........ -break-passcount TRACEPOINT-NUMBER PASSCOUNT Set the passcount for tracepoint TRACEPOINT-NUMBER to PASSCOUNT. If the breakpoint referred to by TRACEPOINT-NUMBER is not a tracepoint, error is emitted. This corresponds to CLI command 'passcount'. The '-break-watch' Command -------------------------- Synopsis ........ -break-watch [ -a | -r ] Create a watchpoint. With the '-a' option it will create an "access" watchpoint, i.e., a watchpoint that triggers either on a read from or on a write to the memory location. With the '-r' option, the watchpoint created is a "read" watchpoint, i.e., it will trigger only when the memory location is accessed for reading. Without either of the options, the watchpoint created is a regular watchpoint, i.e., it will trigger when the memory location is accessed for writing. *Note Setting Watchpoints: Set Watchpoints. Note that '-break-list' will report a single list of watchpoints and breakpoints inserted. GDB Command ........... The corresponding GDB commands are 'watch', 'awatch', and 'rwatch'. Example ....... Setting a watchpoint on a variable in the 'main' function: (gdb) -break-watch x ^done,wpt={number="2",exp="x"} (gdb) -exec-continue ^running (gdb) *stopped,reason="watchpoint-trigger",wpt={number="2",exp="x"}, value={old="-268439212",new="55"}, frame={func="main",args=[],file="recursive2.c", fullname="/home/foo/bar/recursive2.c",line="5"} (gdb) Setting a watchpoint on a variable local to a function. GDB will stop the program execution twice: first for the variable changing value, then for the watchpoint going out of scope. (gdb) -break-watch C ^done,wpt={number="5",exp="C"} (gdb) -exec-continue ^running (gdb) *stopped,reason="watchpoint-trigger", wpt={number="5",exp="C"},value={old="-276895068",new="3"}, frame={func="callee4",args=[], file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"} (gdb) -exec-continue ^running (gdb) *stopped,reason="watchpoint-scope",wpnum="5", frame={func="callee3",args=[{name="strarg", value="0x11940 \"A string argument.\""}], file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"} (gdb) Listing breakpoints and watchpoints, at different points in the program execution. Note that once the watchpoint goes out of scope, it is deleted. (gdb) -break-watch C ^done,wpt={number="2",exp="C"} (gdb) -break-list ^done,BreakpointTable={nr_rows="2",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x00010734",func="callee4", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c"line="8",thread-groups=["i1"], times="1"}, bkpt={number="2",type="watchpoint",disp="keep", enabled="y",addr="",what="C",thread-groups=["i1"],times="0"}]} (gdb) -exec-continue ^running (gdb) *stopped,reason="watchpoint-trigger",wpt={number="2",exp="C"}, value={old="-276895068",new="3"}, frame={func="callee4",args=[], file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="13"} (gdb) -break-list ^done,BreakpointTable={nr_rows="2",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x00010734",func="callee4", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8",thread-groups=["i1"], times="1"}, bkpt={number="2",type="watchpoint",disp="keep", enabled="y",addr="",what="C",thread-groups=["i1"],times="-5"}]} (gdb) -exec-continue ^running ^done,reason="watchpoint-scope",wpnum="2", frame={func="callee3",args=[{name="strarg", value="0x11940 \"A string argument.\""}], file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"} (gdb) -break-list ^done,BreakpointTable={nr_rows="1",nr_cols="6", hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"}, {width="14",alignment="-1",col_name="type",colhdr="Type"}, {width="4",alignment="-1",col_name="disp",colhdr="Disp"}, {width="3",alignment="-1",col_name="enabled",colhdr="Enb"}, {width="10",alignment="-1",col_name="addr",colhdr="Address"}, {width="40",alignment="2",col_name="what",colhdr="What"}], body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x00010734",func="callee4", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/devo/gdb/testsuite/gdb.mi/basics.c",line="8", thread-groups=["i1"],times="1"}]} (gdb)  File: gdb.info, Node: GDB/MI Catchpoint Commands, Next: GDB/MI Program Context, Prev: GDB/MI Breakpoint Commands, Up: GDB/MI 27.9 GDB/MI Catchpoint Commands =============================== This section documents GDB/MI commands for manipulating catchpoints. * Menu: * Shared Library GDB/MI Catchpoint Commands:: * Ada Exception GDB/MI Catchpoint Commands::  File: gdb.info, Node: Shared Library GDB/MI Catchpoint Commands, Next: Ada Exception GDB/MI Catchpoint Commands, Up: GDB/MI Catchpoint Commands 27.9.1 Shared Library GDB/MI Catchpoints ---------------------------------------- The '-catch-load' Command ------------------------- Synopsis ........ -catch-load [ -t ] [ -d ] REGEXP Add a catchpoint for library load events. If the '-t' option is used, the catchpoint is a temporary one (*note Setting Breakpoints: Set Breaks.). If the '-d' option is used, the catchpoint is created in a disabled state. The 'regexp' argument is a regular expression used to match the name of the loaded library. GDB Command ........... The corresponding GDB command is 'catch load'. Example ....... -catch-load -t foo.so ^done,bkpt={number="1",type="catchpoint",disp="del",enabled="y", what="load of library matching foo.so",catch-type="load",times="0"} (gdb) The '-catch-unload' Command --------------------------- Synopsis ........ -catch-unload [ -t ] [ -d ] REGEXP Add a catchpoint for library unload events. If the '-t' option is used, the catchpoint is a temporary one (*note Setting Breakpoints: Set Breaks.). If the '-d' option is used, the catchpoint is created in a disabled state. The 'regexp' argument is a regular expression used to match the name of the unloaded library. GDB Command ........... The corresponding GDB command is 'catch unload'. Example ....... -catch-unload -d bar.so ^done,bkpt={number="2",type="catchpoint",disp="keep",enabled="n", what="load of library matching bar.so",catch-type="unload",times="0"} (gdb)  File: gdb.info, Node: Ada Exception GDB/MI Catchpoint Commands, Prev: Shared Library GDB/MI Catchpoint Commands, Up: GDB/MI Catchpoint Commands 27.9.2 Ada Exception GDB/MI Catchpoints --------------------------------------- The following GDB/MI commands can be used to create catchpoints that stop the execution when Ada exceptions are being raised. The '-catch-assert' Command --------------------------- Synopsis ........ -catch-assert [ -c CONDITION] [ -d ] [ -t ] Add a catchpoint for failed Ada assertions. The possible optional parameters for this command are: '-c CONDITION' Make the catchpoint conditional on CONDITION. '-d' Create a disabled catchpoint. '-t' Create a temporary catchpoint. GDB Command ........... The corresponding GDB command is 'catch assert'. Example ....... -catch-assert ^done,bkptno="5",bkpt={number="5",type="breakpoint",disp="keep", enabled="y",addr="0x0000000000404888",what="failed Ada assertions", thread-groups=["i1"],times="0", original-location="__gnat_debug_raise_assert_failure"} (gdb) The '-catch-exception' Command ------------------------------ Synopsis ........ -catch-exception [ -c CONDITION] [ -d ] [ -e EXCEPTION-NAME ] [ -t ] [ -u ] Add a catchpoint stopping when Ada exceptions are raised. By default, the command stops the program when any Ada exception gets raised. But it is also possible, by using some of the optional parameters described below, to create more selective catchpoints. The possible optional parameters for this command are: '-c CONDITION' Make the catchpoint conditional on CONDITION. '-d' Create a disabled catchpoint. '-e EXCEPTION-NAME' Only stop when EXCEPTION-NAME is raised. This option cannot be used combined with '-u'. '-t' Create a temporary catchpoint. '-u' Stop only when an unhandled exception gets raised. This option cannot be used combined with '-e'. GDB Command ........... The corresponding GDB commands are 'catch exception' and 'catch exception unhandled'. Example ....... -catch-exception -e Program_Error ^done,bkptno="4",bkpt={number="4",type="breakpoint",disp="keep", enabled="y",addr="0x0000000000404874", what="`Program_Error' Ada exception", thread-groups=["i1"], times="0",original-location="__gnat_debug_raise_exception"} (gdb)  File: gdb.info, Node: GDB/MI Program Context, Next: GDB/MI Thread Commands, Prev: GDB/MI Catchpoint Commands, Up: GDB/MI 27.10 GDB/MI Program Context ============================ The '-exec-arguments' Command ----------------------------- Synopsis ........ -exec-arguments ARGS Set the inferior program arguments, to be used in the next '-exec-run'. GDB Command ........... The corresponding GDB command is 'set args'. Example ....... (gdb) -exec-arguments -v word ^done (gdb) The '-environment-cd' Command ----------------------------- Synopsis ........ -environment-cd PATHDIR Set GDB's working directory. GDB Command ........... The corresponding GDB command is 'cd'. Example ....... (gdb) -environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb ^done (gdb) The '-environment-directory' Command ------------------------------------ Synopsis ........ -environment-directory [ -r ] [ PATHDIR ]+ Add directories PATHDIR to beginning of search path for source files. If the '-r' option is used, the search path is reset to the default search path. If directories PATHDIR are supplied in addition to the '-r' option, the search path is first reset and then addition occurs as normal. Multiple directories may be specified, separated by blanks. Specifying multiple directories in a single command results in the directories added to the beginning of the search path in the same order they were presented in the command. If blanks are needed as part of a directory name, double-quotes should be used around the name. In the command output, the path will show up separated by the system directory-separator character. The directory-separator character must not be used in any directory name. If no directories are specified, the current search path is displayed. GDB Command ........... The corresponding GDB command is 'dir'. Example ....... (gdb) -environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd" (gdb) -environment-directory "" ^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd" (gdb) -environment-directory -r /home/jjohnstn/src/gdb /usr/src ^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd" (gdb) -environment-directory -r ^done,source-path="$cdir:$cwd" (gdb) The '-environment-path' Command ------------------------------- Synopsis ........ -environment-path [ -r ] [ PATHDIR ]+ Add directories PATHDIR to beginning of search path for object files. If the '-r' option is used, the search path is reset to the original search path that existed at gdb start-up. If directories PATHDIR are supplied in addition to the '-r' option, the search path is first reset and then addition occurs as normal. Multiple directories may be specified, separated by blanks. Specifying multiple directories in a single command results in the directories added to the beginning of the search path in the same order they were presented in the command. If blanks are needed as part of a directory name, double-quotes should be used around the name. In the command output, the path will show up separated by the system directory-separator character. The directory-separator character must not be used in any directory name. If no directories are specified, the current path is displayed. GDB Command ........... The corresponding GDB command is 'path'. Example ....... (gdb) -environment-path ^done,path="/usr/bin" (gdb) -environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin ^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin" (gdb) -environment-path -r /usr/local/bin ^done,path="/usr/local/bin:/usr/bin" (gdb) The '-environment-pwd' Command ------------------------------ Synopsis ........ -environment-pwd Show the current working directory. GDB Command ........... The corresponding GDB command is 'pwd'. Example ....... (gdb) -environment-pwd ^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb" (gdb)  File: gdb.info, Node: GDB/MI Thread Commands, Next: GDB/MI Ada Tasking Commands, Prev: GDB/MI Program Context, Up: GDB/MI 27.11 GDB/MI Thread Commands ============================ The '-thread-info' Command -------------------------- Synopsis ........ -thread-info [ THREAD-ID ] Reports information about either a specific thread, if the THREAD-ID parameter is present, or about all threads. THREAD-ID is the thread's global thread ID. When printing information about all threads, also reports the global ID of the current thread. GDB Command ........... The 'info thread' command prints the same information about all threads. Result ...... The result is a list of threads. The following attributes are defined for a given thread: 'current' This field exists only for the current thread. It has the value '*'. 'id' The global identifier that GDB uses to refer to the thread. 'target-id' The identifier that the target uses to refer to the thread. 'details' Extra information about the thread, in a target-specific format. This field is optional. 'name' The name of the thread. If the user specified a name using the 'thread name' command, then this name is given. Otherwise, if GDB can extract the thread name from the target, then that name is given. If GDB cannot find the thread name, then this field is omitted. 'frame' The stack frame currently executing in the thread. 'state' The thread's state. The 'state' field may have the following values: 'stopped' The thread is stopped. Frame information is available for stopped threads. 'running' The thread is running. There's no frame information for running threads. 'core' If GDB can find the CPU core on which this thread is running, then this field is the core identifier. This field is optional. Example ....... -thread-info ^done,threads=[ {id="2",target-id="Thread 0xb7e14b90 (LWP 21257)", frame={level="0",addr="0xffffe410",func="__kernel_vsyscall", args=[]},state="running"}, {id="1",target-id="Thread 0xb7e156b0 (LWP 21254)", frame={level="0",addr="0x0804891f",func="foo", args=[{name="i",value="10"}], file="/tmp/a.c",fullname="/tmp/a.c",line="158"}, state="running"}], current-thread-id="1" (gdb) The '-thread-list-ids' Command ------------------------------ Synopsis ........ -thread-list-ids Produces a list of the currently known global GDB thread ids. At the end of the list it also prints the total number of such threads. This command is retained for historical reasons, the '-thread-info' command should be used instead. GDB Command ........... Part of 'info threads' supplies the same information. Example ....... (gdb) -thread-list-ids ^done,thread-ids={thread-id="3",thread-id="2",thread-id="1"}, current-thread-id="1",number-of-threads="3" (gdb) The '-thread-select' Command ---------------------------- Synopsis ........ -thread-select THREAD-ID Make thread with global thread number THREAD-ID the current thread. It prints the number of the new current thread, and the topmost frame for that thread. This command is deprecated in favor of explicitly using the '--thread' option to each command. GDB Command ........... The corresponding GDB command is 'thread'. Example ....... (gdb) -exec-next ^running (gdb) *stopped,reason="end-stepping-range",thread-id="2",line="187", file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c" (gdb) -thread-list-ids ^done, thread-ids={thread-id="3",thread-id="2",thread-id="1"}, number-of-threads="3" (gdb) -thread-select 3 ^done,new-thread-id="3", frame={level="0",func="vprintf", args=[{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""}, {name="arg",value="0x2"}],file="vprintf.c",line="31"} (gdb)  File: gdb.info, Node: GDB/MI Ada Tasking Commands, Next: GDB/MI Program Execution, Prev: GDB/MI Thread Commands, Up: GDB/MI 27.12 GDB/MI Ada Tasking Commands ================================= The '-ada-task-info' Command ---------------------------- Synopsis ........ -ada-task-info [ TASK-ID ] Reports information about either a specific Ada task, if the TASK-ID parameter is present, or about all Ada tasks. GDB Command ........... The 'info tasks' command prints the same information about all Ada tasks (*note Ada Tasks::). Result ...... The result is a table of Ada tasks. The following columns are defined for each Ada task: 'current' This field exists only for the current thread. It has the value '*'. 'id' The identifier that GDB uses to refer to the Ada task. 'task-id' The identifier that the target uses to refer to the Ada task. 'thread-id' The global thread identifier of the thread corresponding to the Ada task. This field should always exist, as Ada tasks are always implemented on top of a thread. But if GDB cannot find this corresponding thread for any reason, the field is omitted. 'parent-id' This field exists only when the task was created by another task. In this case, it provides the ID of the parent task. 'priority' The base priority of the task. 'state' The current state of the task. For a detailed description of the possible states, see *note Ada Tasks::. 'name' The name of the task. Example ....... -ada-task-info ^done,tasks={nr_rows="3",nr_cols="8", hdr=[{width="1",alignment="-1",col_name="current",colhdr=""}, {width="3",alignment="1",col_name="id",colhdr="ID"}, {width="9",alignment="1",col_name="task-id",colhdr="TID"}, {width="4",alignment="1",col_name="thread-id",colhdr=""}, {width="4",alignment="1",col_name="parent-id",colhdr="P-ID"}, {width="3",alignment="1",col_name="priority",colhdr="Pri"}, {width="22",alignment="-1",col_name="state",colhdr="State"}, {width="1",alignment="2",col_name="name",colhdr="Name"}], body=[{current="*",id="1",task-id=" 644010",thread-id="1",priority="48", state="Child Termination Wait",name="main_task"}]} (gdb)  File: gdb.info, Node: GDB/MI Program Execution, Next: GDB/MI Stack Manipulation, Prev: GDB/MI Ada Tasking Commands, Up: GDB/MI 27.13 GDB/MI Program Execution ============================== These are the asynchronous commands which generate the out-of-band record '*stopped'. Currently GDB only really executes asynchronously with remote targets and this interaction is mimicked in other cases. The '-exec-continue' Command ---------------------------- Synopsis ........ -exec-continue [--reverse] [--all|--thread-group N] Resumes the execution of the inferior program, which will continue to execute until it reaches a debugger stop event. If the '--reverse' option is specified, execution resumes in reverse until it reaches a stop event. Stop events may include * breakpoints or watchpoints * signals or exceptions * the end of the process (or its beginning under '--reverse') * the end or beginning of a replay log if one is being used. In all-stop mode (*note All-Stop Mode::), may resume only one thread, or all threads, depending on the value of the 'scheduler-locking' variable. If '--all' is specified, all threads (in all inferiors) will be resumed. The '--all' option is ignored in all-stop mode. If the '--thread-group' options is specified, then all threads in that thread group are resumed. GDB Command ........... The corresponding GDB corresponding is 'continue'. Example ....... -exec-continue ^running (gdb) @Hello world *stopped,reason="breakpoint-hit",disp="keep",bkptno="2",frame={ func="foo",args=[],file="hello.c",fullname="/home/foo/bar/hello.c", line="13"} (gdb) The '-exec-finish' Command -------------------------- Synopsis ........ -exec-finish [--reverse] Resumes the execution of the inferior program until the current function is exited. Displays the results returned by the function. If the '--reverse' option is specified, resumes the reverse execution of the inferior program until the point where current function was called. GDB Command ........... The corresponding GDB command is 'finish'. Example ....... Function returning 'void'. -exec-finish ^running (gdb) @hello from foo *stopped,reason="function-finished",frame={func="main",args=[], file="hello.c",fullname="/home/foo/bar/hello.c",line="7"} (gdb) Function returning other than 'void'. The name of the internal GDB variable storing the result is printed, together with the value itself. -exec-finish ^running (gdb) *stopped,reason="function-finished",frame={addr="0x000107b0",func="foo", args=[{name="a",value="1"],{name="b",value="9"}}, file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, gdb-result-var="$1",return-value="0" (gdb) The '-exec-interrupt' Command ----------------------------- Synopsis ........ -exec-interrupt [--all|--thread-group N] Interrupts the background execution of the target. Note how the token associated with the stop message is the one for the execution command that has been interrupted. The token for the interrupt itself only appears in the '^done' output. If the user is trying to interrupt a non-running program, an error message will be printed. Note that when asynchronous execution is enabled, this command is asynchronous just like other execution commands. That is, first the '^done' response will be printed, and the target stop will be reported after that using the '*stopped' notification. In non-stop mode, only the context thread is interrupted by default. All threads (in all inferiors) will be interrupted if the '--all' option is specified. If the '--thread-group' option is specified, all threads in that group will be interrupted. GDB Command ........... The corresponding GDB command is 'interrupt'. Example ....... (gdb) 111-exec-continue 111^running (gdb) 222-exec-interrupt 222^done (gdb) 111*stopped,signal-name="SIGINT",signal-meaning="Interrupt", frame={addr="0x00010140",func="foo",args=[],file="try.c", fullname="/home/foo/bar/try.c",line="13"} (gdb) (gdb) -exec-interrupt ^error,msg="mi_cmd_exec_interrupt: Inferior not executing." (gdb) The '-exec-jump' Command ------------------------ Synopsis ........ -exec-jump LOCATION Resumes execution of the inferior program at the location specified by parameter. *Note Specify Location::, for a description of the different forms of LOCATION. GDB Command ........... The corresponding GDB command is 'jump'. Example ....... -exec-jump foo.c:10 *running,thread-id="all" ^running The '-exec-next' Command ------------------------ Synopsis ........ -exec-next [--reverse] Resumes execution of the inferior program, stopping when the beginning of the next source line is reached. If the '--reverse' option is specified, resumes reverse execution of the inferior program, stopping at the beginning of the previous source line. If you issue this command on the first line of a function, it will take you back to the caller of that function, to the source line where the function was called. GDB Command ........... The corresponding GDB command is 'next'. Example ....... -exec-next ^running (gdb) *stopped,reason="end-stepping-range",line="8",file="hello.c" (gdb) The '-exec-next-instruction' Command ------------------------------------ Synopsis ........ -exec-next-instruction [--reverse] Executes one machine instruction. If the instruction is a function call, continues until the function returns. If the program stops at an instruction in the middle of a source line, the address will be printed as well. If the '--reverse' option is specified, resumes reverse execution of the inferior program, stopping at the previous instruction. If the previously executed instruction was a return from another function, it will continue to execute in reverse until the call to that function (from the current stack frame) is reached. GDB Command ........... The corresponding GDB command is 'nexti'. Example ....... (gdb) -exec-next-instruction ^running (gdb) *stopped,reason="end-stepping-range", addr="0x000100d4",line="5",file="hello.c" (gdb) The '-exec-return' Command -------------------------- Synopsis ........ -exec-return Makes current function return immediately. Doesn't execute the inferior. Displays the new current frame. GDB Command ........... The corresponding GDB command is 'return'. Example ....... (gdb) 200-break-insert callee4 200^done,bkpt={number="1",addr="0x00010734", file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"} (gdb) 000-exec-run 000^running (gdb) 000*stopped,reason="breakpoint-hit",disp="keep",bkptno="1", frame={func="callee4",args=[], file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"} (gdb) 205-break-delete 205^done (gdb) 111-exec-return 111^done,frame={level="0",func="callee3", args=[{name="strarg", value="0x11940 \"A string argument.\""}], file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="18"} (gdb) The '-exec-run' Command ----------------------- Synopsis ........ -exec-run [ --all | --thread-group N ] [ --start ] Starts execution of the inferior from the beginning. The inferior executes until either a breakpoint is encountered or the program exits. In the latter case the output will include an exit code, if the program has exited exceptionally. When neither the '--all' nor the '--thread-group' option is specified, the current inferior is started. If the '--thread-group' option is specified, it should refer to a thread group of type 'process', and that thread group will be started. If the '--all' option is specified, then all inferiors will be started. Using the '--start' option instructs the debugger to stop the execution at the start of the inferior's main subprogram, following the same behavior as the 'start' command (*note Starting::). GDB Command ........... The corresponding GDB command is 'run'. Examples ........ (gdb) -break-insert main ^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",line="4"} (gdb) -exec-run ^running (gdb) *stopped,reason="breakpoint-hit",disp="keep",bkptno="1", frame={func="main",args=[],file="recursive2.c", fullname="/home/foo/bar/recursive2.c",line="4"} (gdb) Program exited normally: (gdb) -exec-run ^running (gdb) x = 55 *stopped,reason="exited-normally" (gdb) Program exited exceptionally: (gdb) -exec-run ^running (gdb) x = 55 *stopped,reason="exited",exit-code="01" (gdb) Another way the program can terminate is if it receives a signal such as 'SIGINT'. In this case, GDB/MI displays this: (gdb) *stopped,reason="exited-signalled",signal-name="SIGINT", signal-meaning="Interrupt" The '-exec-step' Command ------------------------ Synopsis ........ -exec-step [--reverse] Resumes execution of the inferior program, stopping when the beginning of the next source line is reached, if the next source line is not a function call. If it is, stop at the first instruction of the called function. If the '--reverse' option is specified, resumes reverse execution of the inferior program, stopping at the beginning of the previously executed source line. GDB Command ........... The corresponding GDB command is 'step'. Example ....... Stepping into a function: -exec-step ^running (gdb) *stopped,reason="end-stepping-range", frame={func="foo",args=[{name="a",value="10"}, {name="b",value="0"}],file="recursive2.c", fullname="/home/foo/bar/recursive2.c",line="11"} (gdb) Regular stepping: -exec-step ^running (gdb) *stopped,reason="end-stepping-range",line="14",file="recursive2.c" (gdb) The '-exec-step-instruction' Command ------------------------------------ Synopsis ........ -exec-step-instruction [--reverse] Resumes the inferior which executes one machine instruction. If the '--reverse' option is specified, resumes reverse execution of the inferior program, stopping at the previously executed instruction. The output, once GDB has stopped, will vary depending on whether we have stopped in the middle of a source line or not. In the former case, the address at which the program stopped will be printed as well. GDB Command ........... The corresponding GDB command is 'stepi'. Example ....... (gdb) -exec-step-instruction ^running (gdb) *stopped,reason="end-stepping-range", frame={func="foo",args=[],file="try.c", fullname="/home/foo/bar/try.c",line="10"} (gdb) -exec-step-instruction ^running (gdb) *stopped,reason="end-stepping-range", frame={addr="0x000100f4",func="foo",args=[],file="try.c", fullname="/home/foo/bar/try.c",line="10"} (gdb) The '-exec-until' Command ------------------------- Synopsis ........ -exec-until [ LOCATION ] Executes the inferior until the LOCATION specified in the argument is reached. If there is no argument, the inferior executes until a source line greater than the current one is reached. The reason for stopping in this case will be 'location-reached'. GDB Command ........... The corresponding GDB command is 'until'. Example ....... (gdb) -exec-until recursive2.c:6 ^running (gdb) x = 55 *stopped,reason="location-reached",frame={func="main",args=[], file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="6"} (gdb)  File: gdb.info, Node: GDB/MI Stack Manipulation, Next: GDB/MI Variable Objects, Prev: GDB/MI Program Execution, Up: GDB/MI 27.14 GDB/MI Stack Manipulation Commands ======================================== The '-enable-frame-filters' Command ----------------------------------- -enable-frame-filters GDB allows Python-based frame filters to affect the output of the MI commands relating to stack traces. As there is no way to implement this in a fully backward-compatible way, a front end must request that this functionality be enabled. Once enabled, this feature cannot be disabled. Note that if Python support has not been compiled into GDB, this command will still succeed (and do nothing). The '-stack-info-frame' Command ------------------------------- Synopsis ........ -stack-info-frame Get info on the selected frame. GDB Command ........... The corresponding GDB command is 'info frame' or 'frame' (without arguments). Example ....... (gdb) -stack-info-frame ^done,frame={level="1",addr="0x0001076c",func="callee3", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"} (gdb) The '-stack-info-depth' Command ------------------------------- Synopsis ........ -stack-info-depth [ MAX-DEPTH ] Return the depth of the stack. If the integer argument MAX-DEPTH is specified, do not count beyond MAX-DEPTH frames. GDB Command ........... There's no equivalent GDB command. Example ....... For a stack with frame levels 0 through 11: (gdb) -stack-info-depth ^done,depth="12" (gdb) -stack-info-depth 4 ^done,depth="4" (gdb) -stack-info-depth 12 ^done,depth="12" (gdb) -stack-info-depth 11 ^done,depth="11" (gdb) -stack-info-depth 13 ^done,depth="12" (gdb) The '-stack-list-arguments' Command ----------------------------------- Synopsis ........ -stack-list-arguments [ --no-frame-filters ] [ --skip-unavailable ] PRINT-VALUES [ LOW-FRAME HIGH-FRAME ] Display a list of the arguments for the frames between LOW-FRAME and HIGH-FRAME (inclusive). If LOW-FRAME and HIGH-FRAME are not provided, list the arguments for the whole call stack. If the two arguments are equal, show the single frame at the corresponding level. It is an error if LOW-FRAME is larger than the actual number of frames. On the other hand, HIGH-FRAME may be larger than the actual number of frames, in which case only existing frames will be returned. If PRINT-VALUES is 0 or '--no-values', print only the names of the variables; if it is 1 or '--all-values', print also their values; and if it is 2 or '--simple-values', print the name, type and value for simple data types, and the name and type for arrays, structures and unions. If the option '--no-frame-filters' is supplied, then Python frame filters will not be executed. If the '--skip-unavailable' option is specified, arguments that are not available are not listed. Partially available arguments are still displayed, however. Use of this command to obtain arguments in a single frame is deprecated in favor of the '-stack-list-variables' command. GDB Command ........... GDB does not have an equivalent command. 'gdbtk' has a 'gdb_get_args' command which partially overlaps with the functionality of '-stack-list-arguments'. Example ....... (gdb) -stack-list-frames ^done, stack=[ frame={level="0",addr="0x00010734",func="callee4", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="8"}, frame={level="1",addr="0x0001076c",func="callee3", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="17"}, frame={level="2",addr="0x0001078c",func="callee2", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="22"}, frame={level="3",addr="0x000107b4",func="callee1", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="27"}, frame={level="4",addr="0x000107e0",func="main", file="../../../devo/gdb/testsuite/gdb.mi/basics.c", fullname="/home/foo/bar/devo/gdb/testsuite/gdb.mi/basics.c",line="32"}] (gdb) -stack-list-arguments 0 ^done, stack-args=[ frame={level="0",args=[]}, frame={level="1",args=[name="strarg"]}, frame={level="2",args=[name="intarg",name="strarg"]}, frame={level="3",args=[name="intarg",name="strarg",name="fltarg"]}, frame={level="4",args=[]}] (gdb) -stack-list-arguments 1 ^done, stack-args=[ frame={level="0",args=[]}, frame={level="1", args=[{name="strarg",value="0x11940 \"A string argument.\""}]}, frame={level="2",args=[ {name="intarg",value="2"}, {name="strarg",value="0x11940 \"A string argument.\""}]}, {frame={level="3",args=[ {name="intarg",value="2"}, {name="strarg",value="0x11940 \"A string argument.\""}, {name="fltarg",value="3.5"}]}, frame={level="4",args=[]}] (gdb) -stack-list-arguments 0 2 2 ^done,stack-args=[frame={level="2",args=[name="intarg",name="strarg"]}] (gdb) -stack-list-arguments 1 2 2 ^done,stack-args=[frame={level="2", args=[{name="intarg",value="2"}, {name="strarg",value="0x11940 \"A string argument.\""}]}] (gdb) The '-stack-list-frames' Command -------------------------------- Synopsis ........ -stack-list-frames [ --no-frame-filters LOW-FRAME HIGH-FRAME ] List the frames currently on the stack. For each frame it displays the following info: 'LEVEL' The frame number, 0 being the topmost frame, i.e., the innermost function. 'ADDR' The '$pc' value for that frame. 'FUNC' Function name. 'FILE' File name of the source file where the function lives. 'FULLNAME' The full file name of the source file where the function lives. 'LINE' Line number corresponding to the '$pc'. 'FROM' The shared library where this function is defined. This is only given if the frame's function is not known. If invoked without arguments, this command prints a backtrace for the whole stack. If given two integer arguments, it shows the frames whose levels are between the two arguments (inclusive). If the two arguments are equal, it shows the single frame at the corresponding level. It is an error if LOW-FRAME is larger than the actual number of frames. On the other hand, HIGH-FRAME may be larger than the actual number of frames, in which case only existing frames will be returned. If the option '--no-frame-filters' is supplied, then Python frame filters will not be executed. GDB Command ........... The corresponding GDB commands are 'backtrace' and 'where'. Example ....... Full stack backtrace: (gdb) -stack-list-frames ^done,stack= [frame={level="0",addr="0x0001076c",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="11"}, frame={level="1",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="2",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="3",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="4",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="5",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="6",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="7",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="8",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="9",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="10",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="11",addr="0x00010738",func="main", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="4"}] (gdb) Show frames between LOW_FRAME and HIGH_FRAME: (gdb) -stack-list-frames 3 5 ^done,stack= [frame={level="3",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="4",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}, frame={level="5",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}] (gdb) Show a single frame: (gdb) -stack-list-frames 3 3 ^done,stack= [frame={level="3",addr="0x000107a4",func="foo", file="recursive2.c",fullname="/home/foo/bar/recursive2.c",line="14"}] (gdb) The '-stack-list-locals' Command -------------------------------- Synopsis ........ -stack-list-locals [ --no-frame-filters ] [ --skip-unavailable ] PRINT-VALUES Display the local variable names for the selected frame. If PRINT-VALUES is 0 or '--no-values', print only the names of the variables; if it is 1 or '--all-values', print also their values; and if it is 2 or '--simple-values', print the name, type and value for simple data types, and the name and type for arrays, structures and unions. In this last case, a frontend can immediately display the value of simple data types and create variable objects for other data types when the user wishes to explore their values in more detail. If the option '--no-frame-filters' is supplied, then Python frame filters will not be executed. If the '--skip-unavailable' option is specified, local variables that are not available are not listed. Partially available local variables are still displayed, however. This command is deprecated in favor of the '-stack-list-variables' command. GDB Command ........... 'info locals' in GDB, 'gdb_get_locals' in 'gdbtk'. Example ....... (gdb) -stack-list-locals 0 ^done,locals=[name="A",name="B",name="C"] (gdb) -stack-list-locals --all-values ^done,locals=[{name="A",value="1"},{name="B",value="2"}, {name="C",value="{1, 2, 3}"}] -stack-list-locals --simple-values ^done,locals=[{name="A",type="int",value="1"}, {name="B",type="int",value="2"},{name="C",type="int [3]"}] (gdb) The '-stack-list-variables' Command ----------------------------------- Synopsis ........ -stack-list-variables [ --no-frame-filters ] [ --skip-unavailable ] PRINT-VALUES Display the names of local variables and function arguments for the selected frame. If PRINT-VALUES is 0 or '--no-values', print only the names of the variables; if it is 1 or '--all-values', print also their values; and if it is 2 or '--simple-values', print the name, type and value for simple data types, and the name and type for arrays, structures and unions. If the option '--no-frame-filters' is supplied, then Python frame filters will not be executed. If the '--skip-unavailable' option is specified, local variables and arguments that are not available are not listed. Partially available arguments and local variables are still displayed, however. Example ....... (gdb) -stack-list-variables --thread 1 --frame 0 --all-values ^done,variables=[{name="x",value="11"},{name="s",value="{a = 1, b = 2}"}] (gdb) The '-stack-select-frame' Command --------------------------------- Synopsis ........ -stack-select-frame FRAMENUM Change the selected frame. Select a different frame FRAMENUM on the stack. This command in deprecated in favor of passing the '--frame' option to every command. GDB Command ........... The corresponding GDB commands are 'frame', 'up', 'down', 'select-frame', 'up-silent', and 'down-silent'. Example ....... (gdb) -stack-select-frame 2 ^done (gdb)  File: gdb.info, Node: GDB/MI Variable Objects, Next: GDB/MI Data Manipulation, Prev: GDB/MI Stack Manipulation, Up: GDB/MI 27.15 GDB/MI Variable Objects ============================= Introduction to Variable Objects -------------------------------- Variable objects are "object-oriented" MI interface for examining and changing values of expressions. Unlike some other MI interfaces that work with expressions, variable objects are specifically designed for simple and efficient presentation in the frontend. A variable object is identified by string name. When a variable object is created, the frontend specifies the expression for that variable object. The expression can be a simple variable, or it can be an arbitrary complex expression, and can even involve CPU registers. After creating a variable object, the frontend can invoke other variable object operations--for example to obtain or change the value of a variable object, or to change display format. Variable objects have hierarchical tree structure. Any variable object that corresponds to a composite type, such as structure in C, has a number of child variable objects, for example corresponding to each element of a structure. A child variable object can itself have children, recursively. Recursion ends when we reach leaf variable objects, which always have built-in types. Child variable objects are created only by explicit request, so if a frontend is not interested in the children of a particular variable object, no child will be created. For a leaf variable object it is possible to obtain its value as a string, or set the value from a string. String value can be also obtained for a non-leaf variable object, but it's generally a string that only indicates the type of the object, and does not list its contents. Assignment to a non-leaf variable object is not allowed. A frontend does not need to read the values of all variable objects each time the program stops. Instead, MI provides an update command that lists all variable objects whose values has changed since the last update operation. This considerably reduces the amount of data that must be transferred to the frontend. As noted above, children variable objects are created on demand, and only leaf variable objects have a real value. As result, gdb will read target memory only for leaf variables that frontend has created. The automatic update is not always desirable. For example, a frontend might want to keep a value of some expression for future reference, and never update it. For another example, fetching memory is relatively slow for embedded targets, so a frontend might want to disable automatic update for the variables that are either not visible on the screen, or "closed". This is possible using so called "frozen variable objects". Such variable objects are never implicitly updated. Variable objects can be either "fixed" or "floating". For the fixed variable object, the expression is parsed when the variable object is created, including associating identifiers to specific variables. The meaning of expression never changes. For a floating variable object the values of variables whose names appear in the expressions are re-evaluated every time in the context of the current frame. Consider this example: void do_work(...) { struct work_state state; if (...) do_work(...); } If a fixed variable object for the 'state' variable is created in this function, and we enter the recursive call, the variable object will report the value of 'state' in the top-level 'do_work' invocation. On the other hand, a floating variable object will report the value of 'state' in the current frame. If an expression specified when creating a fixed variable object refers to a local variable, the variable object becomes bound to the thread and frame in which the variable object is created. When such variable object is updated, GDB makes sure that the thread/frame combination the variable object is bound to still exists, and re-evaluates the variable object in context of that thread/frame. The following is the complete set of GDB/MI operations defined to access this functionality: *Operation* *Description* '-enable-pretty-printing' enable Python-based pretty-printing '-var-create' create a variable object '-var-delete' delete the variable object and/or its children '-var-set-format' set the display format of this variable '-var-show-format' show the display format of this variable '-var-info-num-children' tells how many children this object has '-var-list-children' return a list of the object's children '-var-info-type' show the type of this variable object '-var-info-expression' print parent-relative expression that this variable object represents '-var-info-path-expression' print full expression that this variable object represents '-var-show-attributes' is this variable editable? does it exist here? '-var-evaluate-expression' get the value of this variable '-var-assign' set the value of this variable '-var-update' update the variable and its children '-var-set-frozen' set frozeness attribute '-var-set-update-range' set range of children to display on update In the next subsection we describe each operation in detail and suggest how it can be used. Description And Use of Operations on Variable Objects ----------------------------------------------------- The '-enable-pretty-printing' Command ------------------------------------- -enable-pretty-printing GDB allows Python-based visualizers to affect the output of the MI variable object commands. However, because there was no way to implement this in a fully backward-compatible way, a front end must request that this functionality be enabled. Once enabled, this feature cannot be disabled. Note that if Python support has not been compiled into GDB, this command will still succeed (and do nothing). This feature is currently (as of GDB 7.0) experimental, and may work differently in future versions of GDB. The '-var-create' Command ------------------------- Synopsis ........ -var-create {NAME | "-"} {FRAME-ADDR | "*" | "@"} EXPRESSION This operation creates a variable object, which allows the monitoring of a variable, the result of an expression, a memory cell or a CPU register. The NAME parameter is the string by which the object can be referenced. It must be unique. If '-' is specified, the varobj system will generate a string "varNNNNNN" automatically. It will be unique provided that one does not specify NAME of that format. The command fails if a duplicate name is found. The frame under which the expression should be evaluated can be specified by FRAME-ADDR. A '*' indicates that the current frame should be used. A '@' indicates that a floating variable object must be created. EXPRESSION is any expression valid on the current language set (must not begin with a '*'), or one of the following: * '*ADDR', where ADDR is the address of a memory cell * '*ADDR-ADDR' -- a memory address range (TBD) * '$REGNAME' -- a CPU register name A varobj's contents may be provided by a Python-based pretty-printer. In this case the varobj is known as a "dynamic varobj". Dynamic varobjs have slightly different semantics in some cases. If the '-enable-pretty-printing' command is not sent, then GDB will never create a dynamic varobj. This ensures backward compatibility for existing clients. Result ...... This operation returns attributes of the newly-created varobj. These are: 'name' The name of the varobj. 'numchild' The number of children of the varobj. This number is not necessarily reliable for a dynamic varobj. Instead, you must examine the 'has_more' attribute. 'value' The varobj's scalar value. For a varobj whose type is some sort of aggregate (e.g., a 'struct'), or for a dynamic varobj, this value will not be interesting. 'type' The varobj's type. This is a string representation of the type, as would be printed by the GDB CLI. If 'print object' (*note set print object: Print Settings.) is set to 'on', the _actual_ (derived) type of the object is shown rather than the _declared_ one. 'thread-id' If a variable object is bound to a specific thread, then this is the thread's global identifier. 'has_more' For a dynamic varobj, this indicates whether there appear to be any children available. For a non-dynamic varobj, this will be 0. 'dynamic' This attribute will be present and have the value '1' if the varobj is a dynamic varobj. If the varobj is not a dynamic varobj, then this attribute will not be present. 'displayhint' A dynamic varobj can supply a display hint to the front end. The value comes directly from the Python pretty-printer object's 'display_hint' method. *Note Pretty Printing API::. Typical output will look like this: name="NAME",numchild="N",type="TYPE",thread-id="M", has_more="HAS_MORE" The '-var-delete' Command ------------------------- Synopsis ........ -var-delete [ -c ] NAME Deletes a previously created variable object and all of its children. With the '-c' option, just deletes the children. Returns an error if the object NAME is not found. The '-var-set-format' Command ----------------------------- Synopsis ........ -var-set-format NAME FORMAT-SPEC Sets the output format for the value of the object NAME to be FORMAT-SPEC. The syntax for the FORMAT-SPEC is as follows: FORMAT-SPEC ==> {binary | decimal | hexadecimal | octal | natural | zero-hexadecimal} The natural format is the default format choosen automatically based on the variable type (like decimal for an 'int', hex for pointers, etc.). The zero-hexadecimal format has a representation similar to hexadecimal but with padding zeroes to the left of the value. For example, a 32-bit hexadecimal value of 0x1234 would be represented as 0x00001234 in the zero-hexadecimal format. For a variable with children, the format is set only on the variable itself, and the children are not affected. The '-var-show-format' Command ------------------------------ Synopsis ........ -var-show-format NAME Returns the format used to display the value of the object NAME. FORMAT ==> FORMAT-SPEC The '-var-info-num-children' Command ------------------------------------ Synopsis ........ -var-info-num-children NAME Returns the number of children of a variable object NAME: numchild=N Note that this number is not completely reliable for a dynamic varobj. It will return the current number of children, but more children may be available. The '-var-list-children' Command -------------------------------- Synopsis ........ -var-list-children [PRINT-VALUES] NAME [FROM TO] Return a list of the children of the specified variable object and create variable objects for them, if they do not already exist. With a single argument or if PRINT-VALUES has a value of 0 or '--no-values', print only the names of the variables; if PRINT-VALUES is 1 or '--all-values', also print their values; and if it is 2 or '--simple-values' print the name and value for simple data types and just the name for arrays, structures and unions. FROM and TO, if specified, indicate the range of children to report. If FROM or TO is less than zero, the range is reset and all children will be reported. Otherwise, children starting at FROM (zero-based) and up to and excluding TO will be reported. If a child range is requested, it will only affect the current call to '-var-list-children', but not future calls to '-var-update'. For this, you must instead use '-var-set-update-range'. The intent of this approach is to enable a front end to implement any update approach it likes; for example, scrolling a view may cause the front end to request more children with '-var-list-children', and then the front end could call '-var-set-update-range' with a different range to ensure that future updates are restricted to just the visible items. For each child the following results are returned: NAME Name of the variable object created for this child. EXP The expression to be shown to the user by the front end to designate this child. For example this may be the name of a structure member. For a dynamic varobj, this value cannot be used to form an expression. There is no way to do this at all with a dynamic varobj. For C/C++ structures there are several pseudo children returned to designate access qualifiers. For these pseudo children EXP is 'public', 'private', or 'protected'. In this case the type and value are not present. A dynamic varobj will not report the access qualifying pseudo-children, regardless of the language. This information is not available at all with a dynamic varobj. NUMCHILD Number of children this child has. For a dynamic varobj, this will be 0. TYPE The type of the child. If 'print object' (*note set print object: Print Settings.) is set to 'on', the _actual_ (derived) type of the object is shown rather than the _declared_ one. VALUE If values were requested, this is the value. THREAD-ID If this variable object is associated with a thread, this is the thread's global thread id. Otherwise this result is not present. FROZEN If the variable object is frozen, this variable will be present with a value of 1. DISPLAYHINT A dynamic varobj can supply a display hint to the front end. The value comes directly from the Python pretty-printer object's 'display_hint' method. *Note Pretty Printing API::. DYNAMIC This attribute will be present and have the value '1' if the varobj is a dynamic varobj. If the varobj is not a dynamic varobj, then this attribute will not be present. The result may have its own attributes: 'displayhint' A dynamic varobj can supply a display hint to the front end. The value comes directly from the Python pretty-printer object's 'display_hint' method. *Note Pretty Printing API::. 'has_more' This is an integer attribute which is nonzero if there are children remaining after the end of the selected range. Example ....... (gdb) -var-list-children n ^done,numchild=N,children=[child={name=NAME,exp=EXP, numchild=N,type=TYPE},(repeats N times)] (gdb) -var-list-children --all-values n ^done,numchild=N,children=[child={name=NAME,exp=EXP, numchild=N,value=VALUE,type=TYPE},(repeats N times)] The '-var-info-type' Command ---------------------------- Synopsis ........ -var-info-type NAME Returns the type of the specified variable NAME. The type is returned as a string in the same format as it is output by the GDB CLI: type=TYPENAME The '-var-info-expression' Command ---------------------------------- Synopsis ........ -var-info-expression NAME Returns a string that is suitable for presenting this variable object in user interface. The string is generally not valid expression in the current language, and cannot be evaluated. For example, if 'a' is an array, and variable object 'A' was created for 'a', then we'll get this output: (gdb) -var-info-expression A.1 ^done,lang="C",exp="1" Here, the value of 'lang' is the language name, which can be found in *note Supported Languages::. Note that the output of the '-var-list-children' command also includes those expressions, so the '-var-info-expression' command is of limited use. The '-var-info-path-expression' Command --------------------------------------- Synopsis ........ -var-info-path-expression NAME Returns an expression that can be evaluated in the current context and will yield the same value that a variable object has. Compare this with the '-var-info-expression' command, which result can be used only for UI presentation. Typical use of the '-var-info-path-expression' command is creating a watchpoint from a variable object. This command is currently not valid for children of a dynamic varobj, and will give an error when invoked on one. For example, suppose 'C' is a C++ class, derived from class 'Base', and that the 'Base' class has a member called 'm_size'. Assume a variable 'c' is has the type of 'C' and a variable object 'C' was created for variable 'c'. Then, we'll get this output: (gdb) -var-info-path-expression C.Base.public.m_size ^done,path_expr=((Base)c).m_size) The '-var-show-attributes' Command ---------------------------------- Synopsis ........ -var-show-attributes NAME List attributes of the specified variable object NAME: status=ATTR [ ( ,ATTR )* ] where ATTR is '{ { editable | noneditable } | TBD }'. The '-var-evaluate-expression' Command -------------------------------------- Synopsis ........ -var-evaluate-expression [-f FORMAT-SPEC] NAME Evaluates the expression that is represented by the specified variable object and returns its value as a string. The format of the string can be specified with the '-f' option. The possible values of this option are the same as for '-var-set-format' (*note -var-set-format::). If the '-f' option is not specified, the current display format will be used. The current display format can be changed using the '-var-set-format' command. value=VALUE Note that one must invoke '-var-list-children' for a variable before the value of a child variable can be evaluated. The '-var-assign' Command ------------------------- Synopsis ........ -var-assign NAME EXPRESSION Assigns the value of EXPRESSION to the variable object specified by NAME. The object must be 'editable'. If the variable's value is altered by the assign, the variable will show up in any subsequent '-var-update' list. Example ....... (gdb) -var-assign var1 3 ^done,value="3" (gdb) -var-update * ^done,changelist=[{name="var1",in_scope="true",type_changed="false"}] (gdb) The '-var-update' Command ------------------------- Synopsis ........ -var-update [PRINT-VALUES] {NAME | "*"} Reevaluate the expressions corresponding to the variable object NAME and all its direct and indirect children, and return the list of variable objects whose values have changed; NAME must be a root variable object. Here, "changed" means that the result of '-var-evaluate-expression' before and after the '-var-update' is different. If '*' is used as the variable object names, all existing variable objects are updated, except for frozen ones (*note -var-set-frozen::). The option PRINT-VALUES determines whether both names and values, or just names are printed. The possible values of this option are the same as for '-var-list-children' (*note -var-list-children::). It is recommended to use the '--all-values' option, to reduce the number of MI commands needed on each program stop. With the '*' parameter, if a variable object is bound to a currently running thread, it will not be updated, without any diagnostic. If '-var-set-update-range' was previously used on a varobj, then only the selected range of children will be reported. '-var-update' reports all the changed varobjs in a tuple named 'changelist'. Each item in the change list is itself a tuple holding: 'name' The name of the varobj. 'value' If values were requested for this update, then this field will be present and will hold the value of the varobj. 'in_scope' This field is a string which may take one of three values: '"true"' The variable object's current value is valid. '"false"' The variable object does not currently hold a valid value but it may hold one in the future if its associated expression comes back into scope. '"invalid"' The variable object no longer holds a valid value. This can occur when the executable file being debugged has changed, either through recompilation or by using the GDB 'file' command. The front end should normally choose to delete these variable objects. In the future new values may be added to this list so the front should be prepared for this possibility. *Note GDB/MI Development and Front Ends: GDB/MI Development and Front Ends. 'type_changed' This is only present if the varobj is still valid. If the type changed, then this will be the string 'true'; otherwise it will be 'false'. When a varobj's type changes, its children are also likely to have become incorrect. Therefore, the varobj's children are automatically deleted when this attribute is 'true'. Also, the varobj's update range, when set using the '-var-set-update-range' command, is unset. 'new_type' If the varobj's type changed, then this field will be present and will hold the new type. 'new_num_children' For a dynamic varobj, if the number of children changed, or if the type changed, this will be the new number of children. The 'numchild' field in other varobj responses is generally not valid for a dynamic varobj - it will show the number of children that GDB knows about, but because dynamic varobjs lazily instantiate their children, this will not reflect the number of children which may be available. The 'new_num_children' attribute only reports changes to the number of children known by GDB. This is the only way to detect whether an update has removed children (which necessarily can only happen at the end of the update range). 'displayhint' The display hint, if any. 'has_more' This is an integer value, which will be 1 if there are more children available outside the varobj's update range. 'dynamic' This attribute will be present and have the value '1' if the varobj is a dynamic varobj. If the varobj is not a dynamic varobj, then this attribute will not be present. 'new_children' If new children were added to a dynamic varobj within the selected update range (as set by '-var-set-update-range'), then they will be listed in this attribute. Example ....... (gdb) -var-assign var1 3 ^done,value="3" (gdb) -var-update --all-values var1 ^done,changelist=[{name="var1",value="3",in_scope="true", type_changed="false"}] (gdb) The '-var-set-frozen' Command ----------------------------- Synopsis ........ -var-set-frozen NAME FLAG Set the frozenness flag on the variable object NAME. The FLAG parameter should be either '1' to make the variable frozen or '0' to make it unfrozen. If a variable object is frozen, then neither itself, nor any of its children, are implicitly updated by '-var-update' of a parent variable or by '-var-update *'. Only '-var-update' of the variable itself will update its value and values of its children. After a variable object is unfrozen, it is implicitly updated by all subsequent '-var-update' operations. Unfreezing a variable does not update it, only subsequent '-var-update' does. Example ....... (gdb) -var-set-frozen V 1 ^done (gdb) The '-var-set-update-range' command ----------------------------------- Synopsis ........ -var-set-update-range NAME FROM TO Set the range of children to be returned by future invocations of '-var-update'. FROM and TO indicate the range of children to report. If FROM or TO is less than zero, the range is reset and all children will be reported. Otherwise, children starting at FROM (zero-based) and up to and excluding TO will be reported. Example ....... (gdb) -var-set-update-range V 1 2 ^done The '-var-set-visualizer' command --------------------------------- Synopsis ........ -var-set-visualizer NAME VISUALIZER Set a visualizer for the variable object NAME. VISUALIZER is the visualizer to use. The special value 'None' means to disable any visualizer in use. If not 'None', VISUALIZER must be a Python expression. This expression must evaluate to a callable object which accepts a single argument. GDB will call this object with the value of the varobj NAME as an argument (this is done so that the same Python pretty-printing code can be used for both the CLI and MI). When called, this object must return an object which conforms to the pretty-printing interface (*note Pretty Printing API::). The pre-defined function 'gdb.default_visualizer' may be used to select a visualizer by following the built-in process (*note Selecting Pretty-Printers::). This is done automatically when a varobj is created, and so ordinarily is not needed. This feature is only available if Python support is enabled. The MI command '-list-features' (*note GDB/MI Support Commands::) can be used to check this. Example ....... Resetting the visualizer: (gdb) -var-set-visualizer V None ^done Reselecting the default (type-based) visualizer: (gdb) -var-set-visualizer V gdb.default_visualizer ^done Suppose 'SomeClass' is a visualizer class. A lambda expression can be used to instantiate this class for a varobj: (gdb) -var-set-visualizer V "lambda val: SomeClass()" ^done  File: gdb.info, Node: GDB/MI Data Manipulation, Next: GDB/MI Tracepoint Commands, Prev: GDB/MI Variable Objects, Up: GDB/MI 27.16 GDB/MI Data Manipulation ============================== This section describes the GDB/MI commands that manipulate data: examine memory and registers, evaluate expressions, etc. For details about what an addressable memory unit is, *note addressable memory unit::. The '-data-disassemble' Command ------------------------------- Synopsis ........ -data-disassemble [ -s START-ADDR -e END-ADDR ] | [ -f FILENAME -l LINENUM [ -n LINES ] ] -- MODE Where: 'START-ADDR' is the beginning address (or '$pc') 'END-ADDR' is the end address 'FILENAME' is the name of the file to disassemble 'LINENUM' is the line number to disassemble around 'LINES' is the number of disassembly lines to be produced. If it is -1, the whole function will be disassembled, in case no END-ADDR is specified. If END-ADDR is specified as a non-zero value, and LINES is lower than the number of disassembly lines between START-ADDR and END-ADDR, only LINES lines are displayed; if LINES is higher than the number of lines between START-ADDR and END-ADDR, only the lines up to END-ADDR are displayed. 'MODE' is one of: * 0 disassembly only * 1 mixed source and disassembly (deprecated) * 2 disassembly with raw opcodes * 3 mixed source and disassembly with raw opcodes (deprecated) * 4 mixed source and disassembly * 5 mixed source and disassembly with raw opcodes Modes 1 and 3 are deprecated. The output is "source centric" which hasn't proved useful in practice. *Note Machine Code::, for a discussion of the difference between '/m' and '/s' output of the 'disassemble' command. Result ...... The result of the '-data-disassemble' command will be a list named 'asm_insns', the contents of this list depend on the MODE used with the '-data-disassemble' command. For modes 0 and 2 the 'asm_insns' list contains tuples with the following fields: 'address' The address at which this instruction was disassembled. 'func-name' The name of the function this instruction is within. 'offset' The decimal offset in bytes from the start of 'func-name'. 'inst' The text disassembly for this 'address'. 'opcodes' This field is only present for modes 2, 3 and 5. This contains the raw opcode bytes for the 'inst' field. For modes 1, 3, 4 and 5 the 'asm_insns' list contains tuples named 'src_and_asm_line', each of which has the following fields: 'line' The line number within 'file'. 'file' The file name from the compilation unit. This might be an absolute file name or a relative file name depending on the compile command used. 'fullname' Absolute file name of 'file'. It is converted to a canonical form using the source file search path (*note Specifying Source Directories: Source Path.) and after resolving all the symbolic links. If the source file is not found this field will contain the path as present in the debug information. 'line_asm_insn' This is a list of tuples containing the disassembly for 'line' in 'file'. The fields of each tuple are the same as for '-data-disassemble' in MODE 0 and 2, so 'address', 'func-name', 'offset', 'inst', and optionally 'opcodes'. Note that whatever included in the 'inst' field, is not manipulated directly by GDB/MI, i.e., it is not possible to adjust its format. GDB Command ........... The corresponding GDB command is 'disassemble'. Example ....... Disassemble from the current value of '$pc' to '$pc + 20': (gdb) -data-disassemble -s $pc -e "$pc + 20" -- 0 ^done, asm_insns=[ {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}, {address="0x000107c8",func-name="main",offset="12", inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"}, {address="0x000107cc",func-name="main",offset="16", inst="sethi %hi(0x11800), %o2"}, {address="0x000107d0",func-name="main",offset="20", inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"}] (gdb) Disassemble the whole 'main' function. Line 32 is part of 'main'. -data-disassemble -f basics.c -l 32 -- 0 ^done,asm_insns=[ {address="0x000107bc",func-name="main",offset="0", inst="save %sp, -112, %sp"}, {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}, [...] {address="0x0001081c",func-name="main",offset="96",inst="ret "}, {address="0x00010820",func-name="main",offset="100",inst="restore "}] (gdb) Disassemble 3 instructions from the start of 'main': (gdb) -data-disassemble -f basics.c -l 32 -n 3 -- 0 ^done,asm_insns=[ {address="0x000107bc",func-name="main",offset="0", inst="save %sp, -112, %sp"}, {address="0x000107c0",func-name="main",offset="4", inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}] (gdb) Disassemble 3 instructions from the start of 'main' in mixed mode: (gdb) -data-disassemble -f basics.c -l 32 -n 3 -- 1 ^done,asm_insns=[ src_and_asm_line={line="31", file="../../../src/gdb/testsuite/gdb.mi/basics.c", fullname="/absolute/path/to/src/gdb/testsuite/gdb.mi/basics.c", line_asm_insn=[{address="0x000107bc", func-name="main",offset="0",inst="save %sp, -112, %sp"}]}, src_and_asm_line={line="32", file="../../../src/gdb/testsuite/gdb.mi/basics.c", fullname="/absolute/path/to/src/gdb/testsuite/gdb.mi/basics.c", line_asm_insn=[{address="0x000107c0", func-name="main",offset="4",inst="mov 2, %o0"}, {address="0x000107c4",func-name="main",offset="8", inst="sethi %hi(0x11800), %o2"}]}] (gdb) The '-data-evaluate-expression' Command --------------------------------------- Synopsis ........ -data-evaluate-expression EXPR Evaluate EXPR as an expression. The expression could contain an inferior function call. The function call will execute synchronously. If the expression contains spaces, it must be enclosed in double quotes. GDB Command ........... The corresponding GDB commands are 'print', 'output', and 'call'. In 'gdbtk' only, there's a corresponding 'gdb_eval' command. Example ....... In the following example, the numbers that precede the commands are the "tokens" described in *note GDB/MI Command Syntax: GDB/MI Command Syntax. Notice how GDB/MI returns the same tokens in its output. 211-data-evaluate-expression A 211^done,value="1" (gdb) 311-data-evaluate-expression &A 311^done,value="0xefffeb7c" (gdb) 411-data-evaluate-expression A+3 411^done,value="4" (gdb) 511-data-evaluate-expression "A + 3" 511^done,value="4" (gdb) The '-data-list-changed-registers' Command ------------------------------------------ Synopsis ........ -data-list-changed-registers Display a list of the registers that have changed. GDB Command ........... GDB doesn't have a direct analog for this command; 'gdbtk' has the corresponding command 'gdb_changed_register_list'. Example ....... On a PPC MBX board: (gdb) -exec-continue ^running (gdb) *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame={ func="main",args=[],file="try.c",fullname="/home/foo/bar/try.c", line="5"} (gdb) -data-list-changed-registers ^done,changed-registers=["0","1","2","4","5","6","7","8","9", "10","11","13","14","15","16","17","18","19","20","21","22","23", "24","25","26","27","28","30","31","64","65","66","67","69"] (gdb) The '-data-list-register-names' Command --------------------------------------- Synopsis ........ -data-list-register-names [ ( REGNO )+ ] Show a list of register names for the current target. If no arguments are given, it shows a list of the names of all the registers. If integer numbers are given as arguments, it will print a list of the names of the registers corresponding to the arguments. To ensure consistency between a register name and its number, the output list may include empty register names. GDB Command ........... GDB does not have a command which corresponds to '-data-list-register-names'. In 'gdbtk' there is a corresponding command 'gdb_regnames'. Example ....... For the PPC MBX board: (gdb) -data-list-register-names ^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7", "r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18", "r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29", "r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9", "f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20", "f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31", "", "pc","ps","cr","lr","ctr","xer"] (gdb) -data-list-register-names 1 2 3 ^done,register-names=["r1","r2","r3"] (gdb) The '-data-list-register-values' Command ---------------------------------------- Synopsis ........ -data-list-register-values [ --skip-unavailable ] FMT [ ( REGNO )*] Display the registers' contents. The format according to which the registers' contents are to be returned is given by FMT, followed by an optional list of numbers specifying the registers to display. A missing list of numbers indicates that the contents of all the registers must be returned. The '--skip-unavailable' option indicates that only the available registers are to be returned. Allowed formats for FMT are: 'x' Hexadecimal 'o' Octal 't' Binary 'd' Decimal 'r' Raw 'N' Natural GDB Command ........... The corresponding GDB commands are 'info reg', 'info all-reg', and (in 'gdbtk') 'gdb_fetch_registers'. Example ....... For a PPC MBX board (note: line breaks are for readability only, they don't appear in the actual output): (gdb) -data-list-register-values r 64 65 ^done,register-values=[{number="64",value="0xfe00a300"}, {number="65",value="0x00029002"}] (gdb) -data-list-register-values x ^done,register-values=[{number="0",value="0xfe0043c8"}, {number="1",value="0x3fff88"},{number="2",value="0xfffffffe"}, {number="3",value="0x0"},{number="4",value="0xa"}, {number="5",value="0x3fff68"},{number="6",value="0x3fff58"}, {number="7",value="0xfe011e98"},{number="8",value="0x2"}, {number="9",value="0xfa202820"},{number="10",value="0xfa202808"}, {number="11",value="0x1"},{number="12",value="0x0"}, {number="13",value="0x4544"},{number="14",value="0xffdfffff"}, {number="15",value="0xffffffff"},{number="16",value="0xfffffeff"}, {number="17",value="0xefffffed"},{number="18",value="0xfffffffe"}, {number="19",value="0xffffffff"},{number="20",value="0xffffffff"}, {number="21",value="0xffffffff"},{number="22",value="0xfffffff7"}, {number="23",value="0xffffffff"},{number="24",value="0xffffffff"}, {number="25",value="0xffffffff"},{number="26",value="0xfffffffb"}, {number="27",value="0xffffffff"},{number="28",value="0xf7bfffff"}, {number="29",value="0x0"},{number="30",value="0xfe010000"}, {number="31",value="0x0"},{number="32",value="0x0"}, {number="33",value="0x0"},{number="34",value="0x0"}, {number="35",value="0x0"},{number="36",value="0x0"}, {number="37",value="0x0"},{number="38",value="0x0"}, {number="39",value="0x0"},{number="40",value="0x0"}, {number="41",value="0x0"},{number="42",value="0x0"}, {number="43",value="0x0"},{number="44",value="0x0"}, {number="45",value="0x0"},{number="46",value="0x0"}, {number="47",value="0x0"},{number="48",value="0x0"}, {number="49",value="0x0"},{number="50",value="0x0"}, {number="51",value="0x0"},{number="52",value="0x0"}, {number="53",value="0x0"},{number="54",value="0x0"}, {number="55",value="0x0"},{number="56",value="0x0"}, {number="57",value="0x0"},{number="58",value="0x0"}, {number="59",value="0x0"},{number="60",value="0x0"}, {number="61",value="0x0"},{number="62",value="0x0"}, {number="63",value="0x0"},{number="64",value="0xfe00a300"}, {number="65",value="0x29002"},{number="66",value="0x202f04b5"}, {number="67",value="0xfe0043b0"},{number="68",value="0xfe00b3e4"}, {number="69",value="0x20002b03"}] (gdb) The '-data-read-memory' Command ------------------------------- This command is deprecated, use '-data-read-memory-bytes' instead. Synopsis ........ -data-read-memory [ -o BYTE-OFFSET ] ADDRESS WORD-FORMAT WORD-SIZE NR-ROWS NR-COLS [ ASCHAR ] where: 'ADDRESS' An expression specifying the address of the first memory word to be read. Complex expressions containing embedded white space should be quoted using the C convention. 'WORD-FORMAT' The format to be used to print the memory words. The notation is the same as for GDB's 'print' command (*note Output Formats: Output Formats.). 'WORD-SIZE' The size of each memory word in bytes. 'NR-ROWS' The number of rows in the output table. 'NR-COLS' The number of columns in the output table. 'ASCHAR' If present, indicates that each row should include an ASCII dump. The value of ASCHAR is used as a padding character when a byte is not a member of the printable ASCII character set (printable ASCII characters are those whose code is between 32 and 126, inclusively). 'BYTE-OFFSET' An offset to add to the ADDRESS before fetching memory. This command displays memory contents as a table of NR-ROWS by NR-COLS words, each word being WORD-SIZE bytes. In total, 'NR-ROWS * NR-COLS * WORD-SIZE' bytes are read (returned as 'total-bytes'). Should less than the requested number of bytes be returned by the target, the missing words are identified using 'N/A'. The number of bytes read from the target is returned in 'nr-bytes' and the starting address used to read memory in 'addr'. The address of the next/previous row or page is available in 'next-row' and 'prev-row', 'next-page' and 'prev-page'. GDB Command ........... The corresponding GDB command is 'x'. 'gdbtk' has 'gdb_get_mem' memory read command. Example ....... Read six bytes of memory starting at 'bytes+6' but then offset by '-6' bytes. Format as three rows of two columns. One byte per word. Display each word in hex. (gdb) 9-data-read-memory -o -6 -- bytes+6 x 1 3 2 9^done,addr="0x00001390",nr-bytes="6",total-bytes="6", next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396", prev-page="0x0000138a",memory=[ {addr="0x00001390",data=["0x00","0x01"]}, {addr="0x00001392",data=["0x02","0x03"]}, {addr="0x00001394",data=["0x04","0x05"]}] (gdb) Read two bytes of memory starting at address 'shorts + 64' and display as a single word formatted in decimal. (gdb) 5-data-read-memory shorts+64 d 2 1 1 5^done,addr="0x00001510",nr-bytes="2",total-bytes="2", next-row="0x00001512",prev-row="0x0000150e", next-page="0x00001512",prev-page="0x0000150e",memory=[ {addr="0x00001510",data=["128"]}] (gdb) Read thirty two bytes of memory starting at 'bytes+16' and format as eight rows of four columns. Include a string encoding with 'x' used as the non-printable character. (gdb) 4-data-read-memory bytes+16 x 1 8 4 x 4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32", next-row="0x000013c0",prev-row="0x0000139c", next-page="0x000013c0",prev-page="0x00001380",memory=[ {addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"}, {addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"}, {addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"}, {addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"}, {addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"}, {addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"}, {addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"}, {addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"}] (gdb) The '-data-read-memory-bytes' Command ------------------------------------- Synopsis ........ -data-read-memory-bytes [ -o OFFSET ] ADDRESS COUNT where: 'ADDRESS' An expression specifying the address of the first addressable memory unit to be read. Complex expressions containing embedded white space should be quoted using the C convention. 'COUNT' The number of addressable memory units to read. This should be an integer literal. 'OFFSET' The offset relative to ADDRESS at which to start reading. This should be an integer literal. This option is provided so that a frontend is not required to first evaluate address and then perform address arithmetics itself. This command attempts to read all accessible memory regions in the specified range. First, all regions marked as unreadable in the memory map (if one is defined) will be skipped. *Note Memory Region Attributes::. Second, GDB will attempt to read the remaining regions. For each one, if reading full region results in an errors, GDB will try to read a subset of the region. In general, every single memory unit in the region may be readable or not, and the only way to read every readable unit is to try a read at every address, which is not practical. Therefore, GDB will attempt to read all accessible memory units at either beginning or the end of the region, using a binary division scheme. This heuristic works well for reading accross a memory map boundary. Note that if a region has a readable range that is neither at the beginning or the end, GDB will not read it. The result record (*note GDB/MI Result Records::) that is output of the command includes a field named 'memory' whose content is a list of tuples. Each tuple represent a successfully read memory block and has the following fields: 'begin' The start address of the memory block, as hexadecimal literal. 'end' The end address of the memory block, as hexadecimal literal. 'offset' The offset of the memory block, as hexadecimal literal, relative to the start address passed to '-data-read-memory-bytes'. 'contents' The contents of the memory block, in hex. GDB Command ........... The corresponding GDB command is 'x'. Example ....... (gdb) -data-read-memory-bytes &a 10 ^done,memory=[{begin="0xbffff154",offset="0x00000000", end="0xbffff15e", contents="01000000020000000300"}] (gdb) The '-data-write-memory-bytes' Command -------------------------------------- Synopsis ........ -data-write-memory-bytes ADDRESS CONTENTS -data-write-memory-bytes ADDRESS CONTENTS [COUNT] where: 'ADDRESS' An expression specifying the address of the first addressable memory unit to be written. Complex expressions containing embedded white space should be quoted using the C convention. 'CONTENTS' The hex-encoded data to write. It is an error if CONTENTS does not represent an integral number of addressable memory units. 'COUNT' Optional argument indicating the number of addressable memory units to be written. If COUNT is greater than CONTENTS' length, GDB will repeatedly write CONTENTS until it fills COUNT memory units. GDB Command ........... There's no corresponding GDB command. Example ....... (gdb) -data-write-memory-bytes &a "aabbccdd" ^done (gdb) (gdb) -data-write-memory-bytes &a "aabbccdd" 16e ^done (gdb)  File: gdb.info, Node: GDB/MI Tracepoint Commands, Next: GDB/MI Symbol Query, Prev: GDB/MI Data Manipulation, Up: GDB/MI 27.17 GDB/MI Tracepoint Commands ================================ The commands defined in this section implement MI support for tracepoints. For detailed introduction, see *note Tracepoints::. The '-trace-find' Command ------------------------- Synopsis ........ -trace-find MODE [PARAMETERS...] Find a trace frame using criteria defined by MODE and PARAMETERS. The following table lists permissible modes and their parameters. For details of operation, see *note tfind::. 'none' No parameters are required. Stops examining trace frames. 'frame-number' An integer is required as parameter. Selects tracepoint frame with that index. 'tracepoint-number' An integer is required as parameter. Finds next trace frame that corresponds to tracepoint with the specified number. 'pc' An address is required as parameter. Finds next trace frame that corresponds to any tracepoint at the specified address. 'pc-inside-range' Two addresses are required as parameters. Finds next trace frame that corresponds to a tracepoint at an address inside the specified range. Both bounds are considered to be inside the range. 'pc-outside-range' Two addresses are required as parameters. Finds next trace frame that corresponds to a tracepoint at an address outside the specified range. Both bounds are considered to be inside the range. 'line' Line specification is required as parameter. *Note Specify Location::. Finds next trace frame that corresponds to a tracepoint at the specified location. If 'none' was passed as MODE, the response does not have fields. Otherwise, the response may have the following fields: 'found' This field has either '0' or '1' as the value, depending on whether a matching tracepoint was found. 'traceframe' The index of the found traceframe. This field is present iff the 'found' field has value of '1'. 'tracepoint' The index of the found tracepoint. This field is present iff the 'found' field has value of '1'. 'frame' The information about the frame corresponding to the found trace frame. This field is present only if a trace frame was found. *Note GDB/MI Frame Information::, for description of this field. GDB Command ........... The corresponding GDB command is 'tfind'. -trace-define-variable ---------------------- Synopsis ........ -trace-define-variable NAME [ VALUE ] Create trace variable NAME if it does not exist. If VALUE is specified, sets the initial value of the specified trace variable to that value. Note that the NAME should start with the '$' character. GDB Command ........... The corresponding GDB command is 'tvariable'. The '-trace-frame-collected' Command ------------------------------------ Synopsis ........ -trace-frame-collected [--var-print-values VAR_PVAL] [--comp-print-values COMP_PVAL] [--registers-format REGFORMAT] [--memory-contents] This command returns the set of collected objects, register names, trace state variable names, memory ranges and computed expressions that have been collected at a particular trace frame. The optional parameters to the command affect the output format in different ways. See the output description table below for more details. The reported names can be used in the normal manner to create varobjs and inspect the objects themselves. The items returned by this command are categorized so that it is clear which is a variable, which is a register, which is a trace state variable, which is a memory range and which is a computed expression. For instance, if the actions were collect myVar, myArray[myIndex], myObj.field, myPtr->field, myCount + 2 collect *(int*)0xaf02bef0@40 the object collected in its entirety would be 'myVar'. The object 'myArray' would be partially collected, because only the element at index 'myIndex' would be collected. The remaining objects would be computed expressions. An example output would be: (gdb) -trace-frame-collected ^done, explicit-variables=[{name="myVar",value="1"}], computed-expressions=[{name="myArray[myIndex]",value="0"}, {name="myObj.field",value="0"}, {name="myPtr->field",value="1"}, {name="myCount + 2",value="3"}, {name="$tvar1 + 1",value="43970027"}], registers=[{number="0",value="0x7fe2c6e79ec8"}, {number="1",value="0x0"}, {number="2",value="0x4"}, ... {number="125",value="0x0"}], tvars=[{name="$tvar1",current="43970026"}], memory=[{address="0x0000000000602264",length="4"}, {address="0x0000000000615bc0",length="4"}] (gdb) Where: 'explicit-variables' The set of objects that have been collected in their entirety (as opposed to collecting just a few elements of an array or a few struct members). For each object, its name and value are printed. The '--var-print-values' option affects how or whether the value field is output. If VAR_PVAL is 0, then print only the names; if it is 1, print also their values; and if it is 2, print the name, type and value for simple data types, and the name and type for arrays, structures and unions. 'computed-expressions' The set of computed expressions that have been collected at the current trace frame. The '--comp-print-values' option affects this set like the '--var-print-values' option affects the 'explicit-variables' set. See above. 'registers' The registers that have been collected at the current trace frame. For each register collected, the name and current value are returned. The value is formatted according to the '--registers-format' option. See the '-data-list-register-values' command for a list of the allowed formats. The default is 'x'. 'tvars' The trace state variables that have been collected at the current trace frame. For each trace state variable collected, the name and current value are returned. 'memory' The set of memory ranges that have been collected at the current trace frame. Its content is a list of tuples. Each tuple represents a collected memory range and has the following fields: 'address' The start address of the memory range, as hexadecimal literal. 'length' The length of the memory range, as decimal literal. 'contents' The contents of the memory block, in hex. This field is only present if the '--memory-contents' option is specified. GDB Command ........... There is no corresponding GDB command. Example ....... -trace-list-variables --------------------- Synopsis ........ -trace-list-variables Return a table of all defined trace variables. Each element of the table has the following fields: 'name' The name of the trace variable. This field is always present. 'initial' The initial value. This is a 64-bit signed integer. This field is always present. 'current' The value the trace variable has at the moment. This is a 64-bit signed integer. This field is absent iff current value is not defined, for example if the trace was never run, or is presently running. GDB Command ........... The corresponding GDB command is 'tvariables'. Example ....... (gdb) -trace-list-variables ^done,trace-variables={nr_rows="1",nr_cols="3", hdr=[{width="15",alignment="-1",col_name="name",colhdr="Name"}, {width="11",alignment="-1",col_name="initial",colhdr="Initial"}, {width="11",alignment="-1",col_name="current",colhdr="Current"}], body=[variable={name="$trace_timestamp",initial="0"} variable={name="$foo",initial="10",current="15"}]} (gdb) -trace-save ----------- Synopsis ........ -trace-save [ -r ] [ -ctf ] FILENAME Saves the collected trace data to FILENAME. Without the '-r' option, the data is downloaded from the target and saved in a local file. With the '-r' option the target is asked to perform the save. By default, this command will save the trace in the tfile format. You can supply the optional '-ctf' argument to save it the CTF format. See *note Trace Files:: for more information about CTF. GDB Command ........... The corresponding GDB command is 'tsave'. -trace-start ------------ Synopsis ........ -trace-start Starts a tracing experiment. The result of this command does not have any fields. GDB Command ........... The corresponding GDB command is 'tstart'. -trace-status ------------- Synopsis ........ -trace-status Obtains the status of a tracing experiment. The result may include the following fields: 'supported' May have a value of either '0', when no tracing operations are supported, '1', when all tracing operations are supported, or 'file' when examining trace file. In the latter case, examining of trace frame is possible but new tracing experiement cannot be started. This field is always present. 'running' May have a value of either '0' or '1' depending on whether tracing experiement is in progress on target. This field is present if 'supported' field is not '0'. 'stop-reason' Report the reason why the tracing was stopped last time. This field may be absent iff tracing was never stopped on target yet. The value of 'request' means the tracing was stopped as result of the '-trace-stop' command. The value of 'overflow' means the tracing buffer is full. The value of 'disconnection' means tracing was automatically stopped when GDB has disconnected. The value of 'passcount' means tracing was stopped when a tracepoint was passed a maximal number of times for that tracepoint. This field is present if 'supported' field is not '0'. 'stopping-tracepoint' The number of tracepoint whose passcount as exceeded. This field is present iff the 'stop-reason' field has the value of 'passcount'. 'frames' 'frames-created' The 'frames' field is a count of the total number of trace frames in the trace buffer, while 'frames-created' is the total created during the run, including ones that were discarded, such as when a circular trace buffer filled up. Both fields are optional. 'buffer-size' 'buffer-free' These fields tell the current size of the tracing buffer and the remaining space. These fields are optional. 'circular' The value of the circular trace buffer flag. '1' means that the trace buffer is circular and old trace frames will be discarded if necessary to make room, '0' means that the trace buffer is linear and may fill up. 'disconnected' The value of the disconnected tracing flag. '1' means that tracing will continue after GDB disconnects, '0' means that the trace run will stop. 'trace-file' The filename of the trace file being examined. This field is optional, and only present when examining a trace file. GDB Command ........... The corresponding GDB command is 'tstatus'. -trace-stop ----------- Synopsis ........ -trace-stop Stops a tracing experiment. The result of this command has the same fields as '-trace-status', except that the 'supported' and 'running' fields are not output. GDB Command ........... The corresponding GDB command is 'tstop'.  File: gdb.info, Node: GDB/MI Symbol Query, Next: GDB/MI File Commands, Prev: GDB/MI Tracepoint Commands, Up: GDB/MI 27.18 GDB/MI Symbol Query Commands ================================== The '-symbol-list-lines' Command -------------------------------- Synopsis ........ -symbol-list-lines FILENAME Print the list of lines that contain code and their associated program addresses for the given source filename. The entries are sorted in ascending PC order. GDB Command ........... There is no corresponding GDB command. Example ....... (gdb) -symbol-list-lines basics.c ^done,lines=[{pc="0x08048554",line="7"},{pc="0x0804855a",line="8"}] (gdb)  File: gdb.info, Node: GDB/MI File Commands, Next: GDB/MI Target Manipulation, Prev: GDB/MI Symbol Query, Up: GDB/MI 27.19 GDB/MI File Commands ========================== This section describes the GDB/MI commands to specify executable file names and to read in and obtain symbol table information. The '-file-exec-and-symbols' Command ------------------------------------ Synopsis ........ -file-exec-and-symbols FILE Specify the executable file to be debugged. This file is the one from which the symbol table is also read. If no file is specified, the command clears the executable and symbol information. If breakpoints are set when using this command with no arguments, GDB will produce error messages. Otherwise, no output is produced, except a completion notification. GDB Command ........... The corresponding GDB command is 'file'. Example ....... (gdb) -file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx ^done (gdb) The '-file-exec-file' Command ----------------------------- Synopsis ........ -file-exec-file FILE Specify the executable file to be debugged. Unlike '-file-exec-and-symbols', the symbol table is _not_ read from this file. If used without argument, GDB clears the information about the executable file. No output is produced, except a completion notification. GDB Command ........... The corresponding GDB command is 'exec-file'. Example ....... (gdb) -file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx ^done (gdb) The '-file-list-exec-source-file' Command ----------------------------------------- Synopsis ........ -file-list-exec-source-file List the line number, the current source file, and the absolute path to the current source file for the current executable. The macro information field has a value of '1' or '0' depending on whether or not the file includes preprocessor macro information. GDB Command ........... The GDB equivalent is 'info source' Example ....... (gdb) 123-file-list-exec-source-file 123^done,line="1",file="foo.c",fullname="/home/bar/foo.c,macro-info="1" (gdb) The '-file-list-exec-source-files' Command ------------------------------------------ Synopsis ........ -file-list-exec-source-files List the source files for the current executable. It will always output both the filename and fullname (absolute file name) of a source file. GDB Command ........... The GDB equivalent is 'info sources'. 'gdbtk' has an analogous command 'gdb_listfiles'. Example ....... (gdb) -file-list-exec-source-files ^done,files=[ {file=foo.c,fullname=/home/foo.c}, {file=/home/bar.c,fullname=/home/bar.c}, {file=gdb_could_not_find_fullpath.c}] (gdb) The '-file-list-shared-libraries' Command ----------------------------------------- Synopsis ........ -file-list-shared-libraries [ REGEXP ] List the shared libraries in the program. With a regular expression REGEXP, only those libraries whose names match REGEXP are listed. GDB Command ........... The corresponding GDB command is 'info shared'. The fields have a similar meaning to the '=library-loaded' notification. The 'ranges' field specifies the multiple segments belonging to this library. Each range has the following fields: 'from' The address defining the inclusive lower bound of the segment. 'to' The address defining the exclusive upper bound of the segment. Example ....... (gdb) -file-list-exec-source-files ^done,shared-libraries=[ {id="/lib/libfoo.so",target-name="/lib/libfoo.so",host-name="/lib/libfoo.so",symbols-loaded="1",thread-group="i1",ranges=[{from="0x72815989",to="0x728162c0"}]}, {id="/lib/libbar.so",target-name="/lib/libbar.so",host-name="/lib/libbar.so",symbols-loaded="1",thread-group="i1",ranges=[{from="0x76ee48c0",to="0x76ee9160"}]}] (gdb) The '-file-symbol-file' Command ------------------------------- Synopsis ........ -file-symbol-file FILE Read symbol table info from the specified FILE argument. When used without arguments, clears GDB's symbol table info. No output is produced, except for a completion notification. GDB Command ........... The corresponding GDB command is 'symbol-file'. Example ....... (gdb) -file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx ^done (gdb)  File: gdb.info, Node: GDB/MI Target Manipulation, Next: GDB/MI File Transfer Commands, Prev: GDB/MI File Commands, Up: GDB/MI 27.20 GDB/MI Target Manipulation Commands ========================================= The '-target-attach' Command ---------------------------- Synopsis ........ -target-attach PID | GID | FILE Attach to a process PID or a file FILE outside of GDB, or a thread group GID. If attaching to a thread group, the id previously returned by '-list-thread-groups --available' must be used. GDB Command ........... The corresponding GDB command is 'attach'. Example ....... (gdb) -target-attach 34 =thread-created,id="1" *stopped,thread-id="1",frame={addr="0xb7f7e410",func="bar",args=[]} ^done (gdb) The '-target-detach' Command ---------------------------- Synopsis ........ -target-detach [ PID | GID ] Detach from the remote target which normally resumes its execution. If either PID or GID is specified, detaches from either the specified process, or specified thread group. There's no output. GDB Command ........... The corresponding GDB command is 'detach'. Example ....... (gdb) -target-detach ^done (gdb) The '-target-disconnect' Command -------------------------------- Synopsis ........ -target-disconnect Disconnect from the remote target. There's no output and the target is generally not resumed. GDB Command ........... The corresponding GDB command is 'disconnect'. Example ....... (gdb) -target-disconnect ^done (gdb) The '-target-download' Command ------------------------------ Synopsis ........ -target-download Loads the executable onto the remote target. It prints out an update message every half second, which includes the fields: 'section' The name of the section. 'section-sent' The size of what has been sent so far for that section. 'section-size' The size of the section. 'total-sent' The total size of what was sent so far (the current and the previous sections). 'total-size' The size of the overall executable to download. Each message is sent as status record (*note GDB/MI Output Syntax: GDB/MI Output Syntax.). In addition, it prints the name and size of the sections, as they are downloaded. These messages include the following fields: 'section' The name of the section. 'section-size' The size of the section. 'total-size' The size of the overall executable to download. At the end, a summary is printed. GDB Command ........... The corresponding GDB command is 'load'. Example ....... Note: each status message appears on a single line. Here the messages have been broken down so that they can fit onto a page. (gdb) -target-download +download,{section=".text",section-size="6668",total-size="9880"} +download,{section=".text",section-sent="512",section-size="6668", total-sent="512",total-size="9880"} +download,{section=".text",section-sent="1024",section-size="6668", total-sent="1024",total-size="9880"} +download,{section=".text",section-sent="1536",section-size="6668", total-sent="1536",total-size="9880"} +download,{section=".text",section-sent="2048",section-size="6668", total-sent="2048",total-size="9880"} +download,{section=".text",section-sent="2560",section-size="6668", total-sent="2560",total-size="9880"} +download,{section=".text",section-sent="3072",section-size="6668", total-sent="3072",total-size="9880"} +download,{section=".text",section-sent="3584",section-size="6668", total-sent="3584",total-size="9880"} +download,{section=".text",section-sent="4096",section-size="6668", total-sent="4096",total-size="9880"} +download,{section=".text",section-sent="4608",section-size="6668", total-sent="4608",total-size="9880"} +download,{section=".text",section-sent="5120",section-size="6668", total-sent="5120",total-size="9880"} +download,{section=".text",section-sent="5632",section-size="6668", total-sent="5632",total-size="9880"} +download,{section=".text",section-sent="6144",section-size="6668", total-sent="6144",total-size="9880"} +download,{section=".text",section-sent="6656",section-size="6668", total-sent="6656",total-size="9880"} +download,{section=".init",section-size="28",total-size="9880"} +download,{section=".fini",section-size="28",total-size="9880"} +download,{section=".data",section-size="3156",total-size="9880"} +download,{section=".data",section-sent="512",section-size="3156", total-sent="7236",total-size="9880"} +download,{section=".data",section-sent="1024",section-size="3156", total-sent="7748",total-size="9880"} +download,{section=".data",section-sent="1536",section-size="3156", total-sent="8260",total-size="9880"} +download,{section=".data",section-sent="2048",section-size="3156", total-sent="8772",total-size="9880"} +download,{section=".data",section-sent="2560",section-size="3156", total-sent="9284",total-size="9880"} +download,{section=".data",section-sent="3072",section-size="3156", total-sent="9796",total-size="9880"} ^done,address="0x10004",load-size="9880",transfer-rate="6586", write-rate="429" (gdb) GDB Command ........... No equivalent. Example ....... N.A. The '-target-flash-erase' Command --------------------------------- Synopsis ........ -target-flash-erase Erases all known flash memory regions on the target. The corresponding GDB command is 'flash-erase'. The output is a list of flash regions that have been erased, with starting addresses and memory region sizes. (gdb) -target-flash-erase ^done,erased-regions={address="0x0",size="0x40000"} (gdb) The '-target-select' Command ---------------------------- Synopsis ........ -target-select TYPE PARAMETERS ... Connect GDB to the remote target. This command takes two args: 'TYPE' The type of target, for instance 'remote', etc. 'PARAMETERS' Device names, host names and the like. *Note Commands for Managing Targets: Target Commands, for more details. The output is a connection notification, followed by the address at which the target program is, in the following form: ^connected,addr="ADDRESS",func="FUNCTION NAME", args=[ARG LIST] GDB Command ........... The corresponding GDB command is 'target'. Example ....... (gdb) -target-select remote /dev/ttya ^connected,addr="0xfe00a300",func="??",args=[] (gdb)  File: gdb.info, Node: GDB/MI File Transfer Commands, Next: GDB/MI Ada Exceptions Commands, Prev: GDB/MI Target Manipulation, Up: GDB/MI 27.21 GDB/MI File Transfer Commands =================================== The '-target-file-put' Command ------------------------------ Synopsis ........ -target-file-put HOSTFILE TARGETFILE Copy file HOSTFILE from the host system (the machine running GDB) to TARGETFILE on the target system. GDB Command ........... The corresponding GDB command is 'remote put'. Example ....... (gdb) -target-file-put localfile remotefile ^done (gdb) The '-target-file-get' Command ------------------------------ Synopsis ........ -target-file-get TARGETFILE HOSTFILE Copy file TARGETFILE from the target system to HOSTFILE on the host system. GDB Command ........... The corresponding GDB command is 'remote get'. Example ....... (gdb) -target-file-get remotefile localfile ^done (gdb) The '-target-file-delete' Command --------------------------------- Synopsis ........ -target-file-delete TARGETFILE Delete TARGETFILE from the target system. GDB Command ........... The corresponding GDB command is 'remote delete'. Example ....... (gdb) -target-file-delete remotefile ^done (gdb)  File: gdb.info, Node: GDB/MI Ada Exceptions Commands, Next: GDB/MI Support Commands, Prev: GDB/MI File Transfer Commands, Up: GDB/MI 27.22 Ada Exceptions GDB/MI Commands ==================================== The '-info-ada-exceptions' Command ---------------------------------- Synopsis ........ -info-ada-exceptions [ REGEXP] List all Ada exceptions defined within the program being debugged. With a regular expression REGEXP, only those exceptions whose names match REGEXP are listed. GDB Command ........... The corresponding GDB command is 'info exceptions'. Result ...... The result is a table of Ada exceptions. The following columns are defined for each exception: 'name' The name of the exception. 'address' The address of the exception. Example ....... -info-ada-exceptions aint ^done,ada-exceptions={nr_rows="2",nr_cols="2", hdr=[{width="1",alignment="-1",col_name="name",colhdr="Name"}, {width="1",alignment="-1",col_name="address",colhdr="Address"}], body=[{name="constraint_error",address="0x0000000000613da0"}, {name="const.aint_global_e",address="0x0000000000613b00"}]} Catching Ada Exceptions ----------------------- The commands describing how to ask GDB to stop when a program raises an exception are described at *note Ada Exception GDB/MI Catchpoint Commands::.  File: gdb.info, Node: GDB/MI Support Commands, Next: GDB/MI Miscellaneous Commands, Prev: GDB/MI Ada Exceptions Commands, Up: GDB/MI 27.23 GDB/MI Support Commands ============================= Since new commands and features get regularly added to GDB/MI, some commands are available to help front-ends query the debugger about support for these capabilities. Similarly, it is also possible to query GDB about target support of certain features. The '-info-gdb-mi-command' Command ---------------------------------- Synopsis ........ -info-gdb-mi-command CMD_NAME Query support for the GDB/MI command named CMD_NAME. Note that the dash ('-') starting all GDB/MI commands is technically not part of the command name (*note GDB/MI Input Syntax::), and thus should be omitted in CMD_NAME. However, for ease of use, this command also accepts the form with the leading dash. GDB Command ........... There is no corresponding GDB command. Result ...... The result is a tuple. There is currently only one field: 'exists' This field is equal to '"true"' if the GDB/MI command exists, '"false"' otherwise. Example ....... Here is an example where the GDB/MI command does not exist: -info-gdb-mi-command unsupported-command ^done,command={exists="false"} And here is an example where the GDB/MI command is known to the debugger: -info-gdb-mi-command symbol-list-lines ^done,command={exists="true"} The '-list-features' Command ---------------------------- Returns a list of particular features of the MI protocol that this version of gdb implements. A feature can be a command, or a new field in an output of some command, or even an important bugfix. While a frontend can sometimes detect presence of a feature at runtime, it is easier to perform detection at debugger startup. The command returns a list of strings, with each string naming an available feature. Each returned string is just a name, it does not have any internal structure. The list of possible feature names is given below. Example output: (gdb) -list-features ^done,result=["feature1","feature2"] The current list of features is: 'frozen-varobjs' Indicates support for the '-var-set-frozen' command, as well as possible presense of the 'frozen' field in the output of '-varobj-create'. 'pending-breakpoints' Indicates support for the '-f' option to the '-break-insert' command. 'python' Indicates Python scripting support, Python-based pretty-printing commands, and possible presence of the 'display_hint' field in the output of '-var-list-children' 'thread-info' Indicates support for the '-thread-info' command. 'data-read-memory-bytes' Indicates support for the '-data-read-memory-bytes' and the '-data-write-memory-bytes' commands. 'breakpoint-notifications' Indicates that changes to breakpoints and breakpoints created via the CLI will be announced via async records. 'ada-task-info' Indicates support for the '-ada-task-info' command. 'language-option' Indicates that all GDB/MI commands accept the '--language' option (*note Context management::). 'info-gdb-mi-command' Indicates support for the '-info-gdb-mi-command' command. 'undefined-command-error-code' Indicates support for the "undefined-command" error code in error result records, produced when trying to execute an undefined GDB/MI command (*note GDB/MI Result Records::). 'exec-run-start-option' Indicates that the '-exec-run' command supports the '--start' option (*note GDB/MI Program Execution::). The '-list-target-features' Command ----------------------------------- Returns a list of particular features that are supported by the target. Those features affect the permitted MI commands, but unlike the features reported by the '-list-features' command, the features depend on which target GDB is using at the moment. Whenever a target can change, due to commands such as '-target-select', '-target-attach' or '-exec-run', the list of target features may change, and the frontend should obtain it again. Example output: (gdb) -list-target-features ^done,result=["async"] The current list of features is: 'async' Indicates that the target is capable of asynchronous command execution, which means that GDB will accept further commands while the target is running. 'reverse' Indicates that the target is capable of reverse execution. *Note Reverse Execution::, for more information.  File: gdb.info, Node: GDB/MI Miscellaneous Commands, Prev: GDB/MI Support Commands, Up: GDB/MI 27.24 Miscellaneous GDB/MI Commands =================================== The '-gdb-exit' Command ----------------------- Synopsis ........ -gdb-exit Exit GDB immediately. GDB Command ........... Approximately corresponds to 'quit'. Example ....... (gdb) -gdb-exit ^exit The '-gdb-set' Command ---------------------- Synopsis ........ -gdb-set Set an internal GDB variable. GDB Command ........... The corresponding GDB command is 'set'. Example ....... (gdb) -gdb-set $foo=3 ^done (gdb) The '-gdb-show' Command ----------------------- Synopsis ........ -gdb-show Show the current value of a GDB variable. GDB Command ........... The corresponding GDB command is 'show'. Example ....... (gdb) -gdb-show annotate ^done,value="0" (gdb) The '-gdb-version' Command -------------------------- Synopsis ........ -gdb-version Show version information for GDB. Used mostly in testing. GDB Command ........... The GDB equivalent is 'show version'. GDB by default shows this information when you start an interactive session. Example ....... (gdb) -gdb-version ~GNU gdb 5.2.1 ~Copyright 2000 Free Software Foundation, Inc. ~GDB is free software, covered by the GNU General Public License, and ~you are welcome to change it and/or distribute copies of it under ~ certain conditions. ~Type "show copying" to see the conditions. ~There is absolutely no warranty for GDB. Type "show warranty" for ~ details. ~This GDB was configured as "--host=sparc-sun-solaris2.5.1 --target=ppc-eabi". ^done (gdb) The '-list-thread-groups' Command --------------------------------- Synopsis -------- -list-thread-groups [ --available ] [ --recurse 1 ] [ GROUP ... ] Lists thread groups (*note Thread groups::). When a single thread group is passed as the argument, lists the children of that group. When several thread group are passed, lists information about those thread groups. Without any parameters, lists information about all top-level thread groups. Normally, thread groups that are being debugged are reported. With the '--available' option, GDB reports thread groups available on the target. The output of this command may have either a 'threads' result or a 'groups' result. The 'thread' result has a list of tuples as value, with each tuple describing a thread (*note GDB/MI Thread Information::). The 'groups' result has a list of tuples as value, each tuple describing a thread group. If top-level groups are requested (that is, no parameter is passed), or when several groups are passed, the output always has a 'groups' result. The format of the 'group' result is described below. To reduce the number of roundtrips it's possible to list thread groups together with their children, by passing the '--recurse' option and the recursion depth. Presently, only recursion depth of 1 is permitted. If this option is present, then every reported thread group will also include its children, either as 'group' or 'threads' field. In general, any combination of option and parameters is permitted, with the following caveats: * When a single thread group is passed, the output will typically be the 'threads' result. Because threads may not contain anything, the 'recurse' option will be ignored. * When the '--available' option is passed, limited information may be available. In particular, the list of threads of a process might be inaccessible. Further, specifying specific thread groups might not give any performance advantage over listing all thread groups. The frontend should assume that '-list-thread-groups --available' is always an expensive operation and cache the results. The 'groups' result is a list of tuples, where each tuple may have the following fields: 'id' Identifier of the thread group. This field is always present. The identifier is an opaque string; frontends should not try to convert it to an integer, even though it might look like one. 'type' The type of the thread group. At present, only 'process' is a valid type. 'pid' The target-specific process identifier. This field is only present for thread groups of type 'process' and only if the process exists. 'exit-code' The exit code of this group's last exited thread, formatted in octal. This field is only present for thread groups of type 'process' and only if the process is not running. 'num_children' The number of children this thread group has. This field may be absent for an available thread group. 'threads' This field has a list of tuples as value, each tuple describing a thread. It may be present if the '--recurse' option is specified, and it's actually possible to obtain the threads. 'cores' This field is a list of integers, each identifying a core that one thread of the group is running on. This field may be absent if such information is not available. 'executable' The name of the executable file that corresponds to this thread group. The field is only present for thread groups of type 'process', and only if there is a corresponding executable file. Example ------- gdb -list-thread-groups ^done,groups=[{id="17",type="process",pid="yyy",num_children="2"}] -list-thread-groups 17 ^done,threads=[{id="2",target-id="Thread 0xb7e14b90 (LWP 21257)", frame={level="0",addr="0xffffe410",func="__kernel_vsyscall",args=[]},state="running"}, {id="1",target-id="Thread 0xb7e156b0 (LWP 21254)", frame={level="0",addr="0x0804891f",func="foo",args=[{name="i",value="10"}], file="/tmp/a.c",fullname="/tmp/a.c",line="158"},state="running"}]] -list-thread-groups --available ^done,groups=[{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]}] -list-thread-groups --available --recurse 1 ^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2], threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]}, {id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},..] -list-thread-groups --available --recurse 1 17 18 ^done,groups=[{id="17", types="process",pid="yyy",num_children="2",cores=[1,2], threads=[{id="1",target-id="Thread 0xb7e14b90",cores=[1]}, {id="2",target-id="Thread 0xb7e14b90",cores=[2]}]},...] The '-info-os' Command ---------------------- Synopsis ........ -info-os [ TYPE ] If no argument is supplied, the command returns a table of available operating-system-specific information types. If one of these types is supplied as an argument TYPE, then the command returns a table of data of that type. The types of information available depend on the target operating system. GDB Command ........... The corresponding GDB command is 'info os'. Example ....... When run on a GNU/Linux system, the output will look something like this: gdb -info-os ^done,OSDataTable={nr_rows="10",nr_cols="3", hdr=[{width="10",alignment="-1",col_name="col0",colhdr="Type"}, {width="10",alignment="-1",col_name="col1",colhdr="Description"}, {width="10",alignment="-1",col_name="col2",colhdr="Title"}], body=[item={col0="cpus",col1="Listing of all cpus/cores on the system", col2="CPUs"}, item={col0="files",col1="Listing of all file descriptors", col2="File descriptors"}, item={col0="modules",col1="Listing of all loaded kernel modules", col2="Kernel modules"}, item={col0="msg",col1="Listing of all message queues", col2="Message queues"}, item={col0="processes",col1="Listing of all processes", col2="Processes"}, item={col0="procgroups",col1="Listing of all process groups", col2="Process groups"}, item={col0="semaphores",col1="Listing of all semaphores", col2="Semaphores"}, item={col0="shm",col1="Listing of all shared-memory regions", col2="Shared-memory regions"}, item={col0="sockets",col1="Listing of all internet-domain sockets", col2="Sockets"}, item={col0="threads",col1="Listing of all threads", col2="Threads"}] gdb -info-os processes ^done,OSDataTable={nr_rows="190",nr_cols="4", hdr=[{width="10",alignment="-1",col_name="col0",colhdr="pid"}, {width="10",alignment="-1",col_name="col1",colhdr="user"}, {width="10",alignment="-1",col_name="col2",colhdr="command"}, {width="10",alignment="-1",col_name="col3",colhdr="cores"}], body=[item={col0="1",col1="root",col2="/sbin/init",col3="0"}, item={col0="2",col1="root",col2="[kthreadd]",col3="1"}, item={col0="3",col1="root",col2="[ksoftirqd/0]",col3="0"}, ... item={col0="26446",col1="stan",col2="bash",col3="0"}, item={col0="28152",col1="stan",col2="bash",col3="1"}]} (gdb) (Note that the MI output here includes a '"Title"' column that does not appear in command-line 'info os'; this column is useful for MI clients that want to enumerate the types of data, such as in a popup menu, but is needless clutter on the command line, and 'info os' omits it.) The '-add-inferior' Command --------------------------- Synopsis -------- -add-inferior Creates a new inferior (*note Inferiors and Programs::). The created inferior is not associated with any executable. Such association may be established with the '-file-exec-and-symbols' command (*note GDB/MI File Commands::). The command response has a single field, 'inferior', whose value is the identifier of the thread group corresponding to the new inferior. Example ------- gdb -add-inferior ^done,inferior="i3" The '-interpreter-exec' Command ------------------------------- Synopsis -------- -interpreter-exec INTERPRETER COMMAND Execute the specified COMMAND in the given INTERPRETER. GDB Command ----------- The corresponding GDB command is 'interpreter-exec'. Example ------- (gdb) -interpreter-exec console "break main" &"During symbol reading, couldn't parse type; debugger out of date?.\n" &"During symbol reading, bad structure-type format.\n" ~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n" ^done (gdb) The '-inferior-tty-set' Command ------------------------------- Synopsis -------- -inferior-tty-set /dev/pts/1 Set terminal for future runs of the program being debugged. GDB Command ----------- The corresponding GDB command is 'set inferior-tty' /dev/pts/1. Example ------- (gdb) -inferior-tty-set /dev/pts/1 ^done (gdb) The '-inferior-tty-show' Command -------------------------------- Synopsis -------- -inferior-tty-show Show terminal for future runs of program being debugged. GDB Command ----------- The corresponding GDB command is 'show inferior-tty'. Example ------- (gdb) -inferior-tty-set /dev/pts/1 ^done (gdb) -inferior-tty-show ^done,inferior_tty_terminal="/dev/pts/1" (gdb) The '-enable-timings' Command ----------------------------- Synopsis -------- -enable-timings [yes | no] Toggle the printing of the wallclock, user and system times for an MI command as a field in its output. This command is to help frontend developers optimize the performance of their code. No argument is equivalent to 'yes'. GDB Command ----------- No equivalent. Example ------- (gdb) -enable-timings ^done (gdb) -break-insert main ^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y", addr="0x080484ed",func="main",file="myprog.c", fullname="/home/nickrob/myprog.c",line="73",thread-groups=["i1"], times="0"}, time={wallclock="0.05185",user="0.00800",system="0.00000"} (gdb) -enable-timings no ^done (gdb) -exec-run ^running (gdb) *stopped,reason="breakpoint-hit",disp="keep",bkptno="1",thread-id="0", frame={addr="0x080484ed",func="main",args=[{name="argc",value="1"}, {name="argv",value="0xbfb60364"}],file="myprog.c", fullname="/home/nickrob/myprog.c",line="73"} (gdb)  File: gdb.info, Node: Annotations, Next: JIT Interface, Prev: GDB/MI, Up: Top 28 GDB Annotations ****************** This chapter describes annotations in GDB. Annotations were designed to interface GDB to graphical user interfaces or other similar programs which want to interact with GDB at a relatively high level. The annotation mechanism has largely been superseded by GDB/MI (*note GDB/MI::). * Menu: * Annotations Overview:: What annotations are; the general syntax. * Server Prefix:: Issuing a command without affecting user state. * Prompting:: Annotations marking GDB's need for input. * Errors:: Annotations for error messages. * Invalidation:: Some annotations describe things now invalid. * Annotations for Running:: Whether the program is running, how it stopped, etc. * Source Annotations:: Annotations describing source code.  File: gdb.info, Node: Annotations Overview, Next: Server Prefix, Up: Annotations 28.1 What is an Annotation? =========================== Annotations start with a newline character, two 'control-z' characters, and the name of the annotation. If there is no additional information associated with this annotation, the name of the annotation is followed immediately by a newline. If there is additional information, the name of the annotation is followed by a space, the additional information, and a newline. The additional information cannot contain newline characters. Any output not beginning with a newline and two 'control-z' characters denotes literal output from GDB. Currently there is no need for GDB to output a newline followed by two 'control-z' characters, but if there was such a need, the annotations could be extended with an 'escape' annotation which means those three characters as output. The annotation LEVEL, which is specified using the '--annotate' command line option (*note Mode Options::), controls how much information GDB prints together with its prompt, values of expressions, source lines, and other types of output. Level 0 is for no annotations, level 1 is for use when GDB is run as a subprocess of GNU Emacs, level 3 is the maximum annotation suitable for programs that control GDB, and level 2 annotations have been made obsolete (*note Limitations of the Annotation Interface: (annotate)Limitations.). 'set annotate LEVEL' The GDB command 'set annotate' sets the level of annotations to the specified LEVEL. 'show annotate' Show the current annotation level. This chapter describes level 3 annotations. A simple example of starting up GDB with annotations is: $ gdb --annotate=3 GNU gdb 6.0 Copyright 2003 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386-pc-linux-gnu" ^Z^Zpre-prompt (gdb) ^Z^Zprompt quit ^Z^Zpost-prompt $ Here 'quit' is input to GDB; the rest is output from GDB. The three lines beginning '^Z^Z' (where '^Z' denotes a 'control-z' character) are annotations; the rest is output from GDB.  File: gdb.info, Node: Server Prefix, Next: Prompting, Prev: Annotations Overview, Up: Annotations 28.2 The Server Prefix ====================== If you prefix a command with 'server ' then it will not affect the command history, nor will it affect GDB's notion of which command to repeat if is pressed on a line by itself. This means that commands can be run behind a user's back by a front-end in a transparent manner. The 'server ' prefix does not affect the recording of values into the value history; to print a value without recording it into the value history, use the 'output' command instead of the 'print' command. Using this prefix also disables confirmation requests (*note confirmation requests::).  File: gdb.info, Node: Prompting, Next: Errors, Prev: Server Prefix, Up: Annotations 28.3 Annotation for GDB Input ============================= When GDB prompts for input, it annotates this fact so it is possible to know when to send output, when the output from a given command is over, etc. Different kinds of input each have a different "input type". Each input type has three annotations: a 'pre-' annotation, which denotes the beginning of any prompt which is being output, a plain annotation, which denotes the end of the prompt, and then a 'post-' annotation which denotes the end of any echo which may (or may not) be associated with the input. For example, the 'prompt' input type features the following annotations: ^Z^Zpre-prompt ^Z^Zprompt ^Z^Zpost-prompt The input types are 'prompt' When GDB is prompting for a command (the main GDB prompt). 'commands' When GDB prompts for a set of commands, like in the 'commands' command. The annotations are repeated for each command which is input. 'overload-choice' When GDB wants the user to select between various overloaded functions. 'query' When GDB wants the user to confirm a potentially dangerous operation. 'prompt-for-continue' When GDB is asking the user to press return to continue. Note: Don't expect this to work well; instead use 'set height 0' to disable prompting. This is because the counting of lines is buggy in the presence of annotations.  File: gdb.info, Node: Errors, Next: Invalidation, Prev: Prompting, Up: Annotations 28.4 Errors =========== ^Z^Zquit This annotation occurs right before GDB responds to an interrupt. ^Z^Zerror This annotation occurs right before GDB responds to an error. Quit and error annotations indicate that any annotations which GDB was in the middle of may end abruptly. For example, if a 'value-history-begin' annotation is followed by a 'error', one cannot expect to receive the matching 'value-history-end'. One cannot expect not to receive it either, however; an error annotation does not necessarily mean that GDB is immediately returning all the way to the top level. A quit or error annotation may be preceded by ^Z^Zerror-begin Any output between that and the quit or error annotation is the error message. Warning messages are not yet annotated.  File: gdb.info, Node: Invalidation, Next: Annotations for Running, Prev: Errors, Up: Annotations 28.5 Invalidation Notices ========================= The following annotations say that certain pieces of state may have changed. '^Z^Zframes-invalid' The frames (for example, output from the 'backtrace' command) may have changed. '^Z^Zbreakpoints-invalid' The breakpoints may have changed. For example, the user just added or deleted a breakpoint.  File: gdb.info, Node: Annotations for Running, Next: Source Annotations, Prev: Invalidation, Up: Annotations 28.6 Running the Program ======================== When the program starts executing due to a GDB command such as 'step' or 'continue', ^Z^Zstarting is output. When the program stops, ^Z^Zstopped is output. Before the 'stopped' annotation, a variety of annotations describe how the program stopped. '^Z^Zexited EXIT-STATUS' The program exited, and EXIT-STATUS is the exit status (zero for successful exit, otherwise nonzero). '^Z^Zsignalled' The program exited with a signal. After the '^Z^Zsignalled', the annotation continues: INTRO-TEXT ^Z^Zsignal-name NAME ^Z^Zsignal-name-end MIDDLE-TEXT ^Z^Zsignal-string STRING ^Z^Zsignal-string-end END-TEXT where NAME is the name of the signal, such as 'SIGILL' or 'SIGSEGV', and STRING is the explanation of the signal, such as 'Illegal Instruction' or 'Segmentation fault'. The arguments INTRO-TEXT, MIDDLE-TEXT, and END-TEXT are for the user's benefit and have no particular format. '^Z^Zsignal' The syntax of this annotation is just like 'signalled', but GDB is just saying that the program received the signal, not that it was terminated with it. '^Z^Zbreakpoint NUMBER' The program hit breakpoint number NUMBER. '^Z^Zwatchpoint NUMBER' The program hit watchpoint number NUMBER.  File: gdb.info, Node: Source Annotations, Prev: Annotations for Running, Up: Annotations 28.7 Displaying Source ====================== The following annotation is used instead of displaying source code: ^Z^Zsource FILENAME:LINE:CHARACTER:MIDDLE:ADDR where FILENAME is an absolute file name indicating which source file, LINE is the line number within that file (where 1 is the first line in the file), CHARACTER is the character position within the file (where 0 is the first character in the file) (for most debug formats this will necessarily point to the beginning of a line), MIDDLE is 'middle' if ADDR is in the middle of the line, or 'beg' if ADDR is at the beginning of the line, and ADDR is the address in the target program associated with the source which is being displayed. The ADDR is in the form '0x' followed by one or more lowercase hex digits (note that this does not depend on the language).  File: gdb.info, Node: JIT Interface, Next: In-Process Agent, Prev: Annotations, Up: Top 29 JIT Compilation Interface **************************** This chapter documents GDB's "just-in-time" (JIT) compilation interface. A JIT compiler is a program or library that generates native executable code at runtime and executes it, usually in order to achieve good performance while maintaining platform independence. Programs that use JIT compilation are normally difficult to debug because portions of their code are generated at runtime, instead of being loaded from object files, which is where GDB normally finds the program's symbols and debug information. In order to debug programs that use JIT compilation, GDB has an interface that allows the program to register in-memory symbol files with GDB at runtime. If you are using GDB to debug a program that uses this interface, then it should work transparently so long as you have not stripped the binary. If you are developing a JIT compiler, then the interface is documented in the rest of this chapter. At this time, the only known client of this interface is the LLVM JIT. Broadly speaking, the JIT interface mirrors the dynamic loader interface. The JIT compiler communicates with GDB by writing data into a global variable and calling a fuction at a well-known symbol. When GDB attaches, it reads a linked list of symbol files from the global variable to find existing code, and puts a breakpoint in the function so that it can find out about additional code. * Menu: * Declarations:: Relevant C struct declarations * Registering Code:: Steps to register code * Unregistering Code:: Steps to unregister code * Custom Debug Info:: Emit debug information in a custom format  File: gdb.info, Node: Declarations, Next: Registering Code, Up: JIT Interface 29.1 JIT Declarations ===================== These are the relevant struct declarations that a C program should include to implement the interface: typedef enum { JIT_NOACTION = 0, JIT_REGISTER_FN, JIT_UNREGISTER_FN } jit_actions_t; struct jit_code_entry { struct jit_code_entry *next_entry; struct jit_code_entry *prev_entry; const char *symfile_addr; uint64_t symfile_size; }; struct jit_descriptor { uint32_t version; /* This type should be jit_actions_t, but we use uint32_t to be explicit about the bitwidth. */ uint32_t action_flag; struct jit_code_entry *relevant_entry; struct jit_code_entry *first_entry; }; /* GDB puts a breakpoint in this function. */ void __attribute__((noinline)) __jit_debug_register_code() { }; /* Make sure to specify the version statically, because the debugger may check the version before we can set it. */ struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 }; If the JIT is multi-threaded, then it is important that the JIT synchronize any modifications to this global data properly, which can easily be done by putting a global mutex around modifications to these structures.  File: gdb.info, Node: Registering Code, Next: Unregistering Code, Prev: Declarations, Up: JIT Interface 29.2 Registering Code ===================== To register code with GDB, the JIT should follow this protocol: * Generate an object file in memory with symbols and other desired debug information. The file must include the virtual addresses of the sections. * Create a code entry for the file, which gives the start and size of the symbol file. * Add it to the linked list in the JIT descriptor. * Point the relevant_entry field of the descriptor at the entry. * Set 'action_flag' to 'JIT_REGISTER' and call '__jit_debug_register_code'. When GDB is attached and the breakpoint fires, GDB uses the 'relevant_entry' pointer so it doesn't have to walk the list looking for new code. However, the linked list must still be maintained in order to allow GDB to attach to a running process and still find the symbol files.  File: gdb.info, Node: Unregistering Code, Next: Custom Debug Info, Prev: Registering Code, Up: JIT Interface 29.3 Unregistering Code ======================= If code is freed, then the JIT should use the following protocol: * Remove the code entry corresponding to the code from the linked list. * Point the 'relevant_entry' field of the descriptor at the code entry. * Set 'action_flag' to 'JIT_UNREGISTER' and call '__jit_debug_register_code'. If the JIT frees or recompiles code without unregistering it, then GDB and the JIT will leak the memory used for the associated symbol files.  File: gdb.info, Node: Custom Debug Info, Prev: Unregistering Code, Up: JIT Interface 29.4 Custom Debug Info ====================== Generating debug information in platform-native file formats (like ELF or COFF) may be an overkill for JIT compilers; especially if all the debug info is used for is displaying a meaningful backtrace. The issue can be resolved by having the JIT writers decide on a debug info format and also provide a reader that parses the debug info generated by the JIT compiler. This section gives a brief overview on writing such a parser. More specific details can be found in the source file 'gdb/jit-reader.in', which is also installed as a header at 'INCLUDEDIR/gdb/jit-reader.h' for easy inclusion. The reader is implemented as a shared object (so this functionality is not available on platforms which don't allow loading shared objects at runtime). Two GDB commands, 'jit-reader-load' and 'jit-reader-unload' are provided, to be used to load and unload the readers from a preconfigured directory. Once loaded, the shared object is used the parse the debug information emitted by the JIT compiler. * Menu: * Using JIT Debug Info Readers:: How to use supplied readers correctly * Writing JIT Debug Info Readers:: Creating a debug-info reader  File: gdb.info, Node: Using JIT Debug Info Readers, Next: Writing JIT Debug Info Readers, Up: Custom Debug Info 29.4.1 Using JIT Debug Info Readers ----------------------------------- Readers can be loaded and unloaded using the 'jit-reader-load' and 'jit-reader-unload' commands. 'jit-reader-load READER' Load the JIT reader named READER, which is a shared object specified as either an absolute or a relative file name. In the latter case, GDB will try to load the reader from a pre-configured directory, usually 'LIBDIR/gdb/' on a UNIX system (here LIBDIR is the system library directory, often '/usr/local/lib'). Only one reader can be active at a time; trying to load a second reader when one is already loaded will result in GDB reporting an error. A new JIT reader can be loaded by first unloading the current one using 'jit-reader-unload' and then invoking 'jit-reader-load'. 'jit-reader-unload' Unload the currently loaded JIT reader.  File: gdb.info, Node: Writing JIT Debug Info Readers, Prev: Using JIT Debug Info Readers, Up: Custom Debug Info 29.4.2 Writing JIT Debug Info Readers ------------------------------------- As mentioned, a reader is essentially a shared object conforming to a certain ABI. This ABI is described in 'jit-reader.h'. 'jit-reader.h' defines the structures, macros and functions required to write a reader. It is installed (along with GDB), in 'INCLUDEDIR/gdb' where INCLUDEDIR is the system include directory. Readers need to be released under a GPL compatible license. A reader can be declared as released under such a license by placing the macro 'GDB_DECLARE_GPL_COMPATIBLE_READER' in a source file. The entry point for readers is the symbol 'gdb_init_reader', which is expected to be a function with the prototype extern struct gdb_reader_funcs *gdb_init_reader (void); 'struct gdb_reader_funcs' contains a set of pointers to callback functions. These functions are executed to read the debug info generated by the JIT compiler ('read'), to unwind stack frames ('unwind') and to create canonical frame IDs ('get_Frame_id'). It also has a callback that is called when the reader is being unloaded ('destroy'). The struct looks like this struct gdb_reader_funcs { /* Must be set to GDB_READER_INTERFACE_VERSION. */ int reader_version; /* For use by the reader. */ void *priv_data; gdb_read_debug_info *read; gdb_unwind_frame *unwind; gdb_get_frame_id *get_frame_id; gdb_destroy_reader *destroy; }; The callbacks are provided with another set of callbacks by GDB to do their job. For 'read', these callbacks are passed in a 'struct gdb_symbol_callbacks' and for 'unwind' and 'get_frame_id', in a 'struct gdb_unwind_callbacks'. 'struct gdb_symbol_callbacks' has callbacks to create new object files and new symbol tables inside those object files. 'struct gdb_unwind_callbacks' has callbacks to read registers off the current frame and to write out the values of the registers in the previous frame. Both have a callback ('target_read') to read bytes off the target's address space.  File: gdb.info, Node: In-Process Agent, Next: GDB Bugs, Prev: JIT Interface, Up: Top 30 In-Process Agent ******************* The traditional debugging model is conceptually low-speed, but works fine, because most bugs can be reproduced in debugging-mode execution. However, as multi-core or many-core processors are becoming mainstream, and multi-threaded programs become more and more popular, there should be more and more bugs that only manifest themselves at normal-mode execution, for example, thread races, because debugger's interference with the program's timing may conceal the bugs. On the other hand, in some applications, it is not feasible for the debugger to interrupt the program's execution long enough for the developer to learn anything helpful about its behavior. If the program's correctness depends on its real-time behavior, delays introduced by a debugger might cause the program to fail, even when the code itself is correct. It is useful to be able to observe the program's behavior without interrupting it. Therefore, traditional debugging model is too intrusive to reproduce some bugs. In order to reduce the interference with the program, we can reduce the number of operations performed by debugger. The "In-Process Agent", a shared library, is running within the same process with inferior, and is able to perform some debugging operations itself. As a result, debugger is only involved when necessary, and performance of debugging can be improved accordingly. Note that interference with program can be reduced but can't be removed completely, because the in-process agent will still stop or slow down the program. The in-process agent can interpret and execute Agent Expressions (*note Agent Expressions::) during performing debugging operations. The agent expressions can be used for different purposes, such as collecting data in tracepoints, and condition evaluation in breakpoints. You can control whether the in-process agent is used as an aid for debugging with the following commands: 'set agent on' Causes the in-process agent to perform some operations on behalf of the debugger. Just which operations requested by the user will be done by the in-process agent depends on the its capabilities. For example, if you request to evaluate breakpoint conditions in the in-process agent, and the in-process agent has such capability as well, then breakpoint conditions will be evaluated in the in-process agent. 'set agent off' Disables execution of debugging operations by the in-process agent. All of the operations will be performed by GDB. 'show agent' Display the current setting of execution of debugging operations by the in-process agent. * Menu: * In-Process Agent Protocol::  File: gdb.info, Node: In-Process Agent Protocol, Up: In-Process Agent 30.1 In-Process Agent Protocol ============================== The in-process agent is able to communicate with both GDB and GDBserver (*note In-Process Agent::). This section documents the protocol used for communications between GDB or GDBserver and the IPA. In general, GDB or GDBserver sends commands (*note IPA Protocol Commands::) and data to in-process agent, and then in-process agent replies back with the return result of the command, or some other information. The data sent to in-process agent is composed of primitive data types, such as 4-byte or 8-byte type, and composite types, which are called objects (*note IPA Protocol Objects::). * Menu: * IPA Protocol Objects:: * IPA Protocol Commands::  File: gdb.info, Node: IPA Protocol Objects, Next: IPA Protocol Commands, Up: In-Process Agent Protocol 30.1.1 IPA Protocol Objects --------------------------- The commands sent to and results received from agent may contain some complex data types called "objects". The in-process agent is running on the same machine with GDB or GDBserver, so it doesn't have to handle as much differences between two ends as remote protocol (*note Remote Protocol::) tries to handle. However, there are still some differences of two ends in two processes: 1. word size. On some 64-bit machines, GDB or GDBserver can be compiled as a 64-bit executable, while in-process agent is a 32-bit one. 2. ABI. Some machines may have multiple types of ABI, GDB or GDBserver is compiled with one, and in-process agent is compiled with the other one. Here are the IPA Protocol Objects: 1. agent expression object. It represents an agent expression (*note Agent Expressions::). 2. tracepoint action object. It represents a tracepoint action (*note Tracepoint Action Lists: Tracepoint Actions.) to collect registers, memory, static trace data and to evaluate expression. 3. tracepoint object. It represents a tracepoint (*note Tracepoints::). The following table describes important attributes of each IPA protocol object: Name Size Description --------------------------------------------------------------------------- _agent expression object_ length 4 length of bytes code byte code LENGTH contents of byte code _tracepoint action for collecting memory_ 'M' 1 type of tracepoint action addr 8 if BASEREG is '-1', ADDR is the address of the lowest byte to collect, otherwise ADDR is the offset of BASEREG for memory collecting. len 8 length of memory for collecting basereg 4 the register number containing the starting memory address for collecting. _tracepoint action for collecting registers_ 'R' 1 type of tracepoint action _tracepoint action for collecting static trace data_ 'L' 1 type of tracepoint action _tracepoint action for expression evaluation_ 'X' 1 type of tracepoint action agent expression length of *note agent expression object:: _tracepoint object_ number 4 number of tracepoint address 8 address of tracepoint inserted on type 4 type of tracepoint enabled 1 enable or disable of tracepoint step_count 8 step pass_count 8 pass numactions 4 number of tracepoint actions hit count 8 hit count trace frame usage 8 trace frame usage compiled_cond 8 compiled condition orig_size 8 orig size condition 4 if zero if condition is NULL, condition is otherwise is NULL *note agent expression object:: otherwise length of *note agent expression object:: actions variable numactions number of *note tracepoint action object::  File: gdb.info, Node: IPA Protocol Commands, Prev: IPA Protocol Objects, Up: In-Process Agent Protocol 30.1.2 IPA Protocol Commands ---------------------------- The spaces in each command are delimiters to ease reading this commands specification. They don't exist in real commands. 'FastTrace:TRACEPOINT_OBJECT GDB_JUMP_PAD_HEAD' Installs a new fast tracepoint described by TRACEPOINT_OBJECT (*note tracepoint object::). The GDB_JUMP_PAD_HEAD, 8-byte long, is the head of "jumppad", which is used to jump to data collection routine in IPA finally. Replies: 'OK TARGET_ADDRESS GDB_JUMP_PAD_HEAD FJUMP_SIZE FJUMP' TARGET_ADDRESS is address of tracepoint in the inferior. The GDB_JUMP_PAD_HEAD is updated head of jumppad. Both of TARGET_ADDRESS and GDB_JUMP_PAD_HEAD are 8-byte long. The FJUMP contains a sequence of instructions jump to jumppad entry. The FJUMP_SIZE, 4-byte long, is the size of FJUMP. 'E NN' for an error 'close' Closes the in-process agent. This command is sent when GDB or GDBserver is about to kill inferiors. 'qTfSTM' *Note qTfSTM::. 'qTsSTM' *Note qTsSTM::. 'qTSTMat' *Note qTSTMat::. 'probe_marker_at:ADDRESS' Asks in-process agent to probe the marker at ADDRESS. Replies: 'E NN' for an error 'unprobe_marker_at:ADDRESS' Asks in-process agent to unprobe the marker at ADDRESS.  File: gdb.info, Node: GDB Bugs, Next: Command Line Editing, Prev: In-Process Agent, Up: Top 31 Reporting Bugs in GDB ************************ Your bug reports play an essential role in making GDB reliable. Reporting a bug may help you by bringing a solution to your problem, or it may not. But in any case the principal function of a bug report is to help the entire community by making the next version of GDB work better. Bug reports are your contribution to the maintenance of GDB. In order for a bug report to serve its purpose, you must include the information that enables us to fix the bug. * Menu: * Bug Criteria:: Have you found a bug? * Bug Reporting:: How to report bugs  File: gdb.info, Node: Bug Criteria, Next: Bug Reporting, Up: GDB Bugs 31.1 Have You Found a Bug? ========================== If you are not sure whether you have found a bug, here are some guidelines: * If the debugger gets a fatal signal, for any input whatever, that is a GDB bug. Reliable debuggers never crash. * If GDB produces an error message for valid input, that is a bug. (Note that if you're cross debugging, the problem may also be somewhere in the connection to the target.) * If GDB does not produce an error message for invalid input, that is a bug. However, you should note that your idea of "invalid input" might be our idea of "an extension" or "support for traditional practice". * If you are an experienced user of debugging tools, your suggestions for improvement of GDB are welcome in any case.  File: gdb.info, Node: Bug Reporting, Prev: Bug Criteria, Up: GDB Bugs 31.2 How to Report Bugs ======================= A number of companies and individuals offer support for GNU products. If you obtained GDB from a support organization, we recommend you contact that organization first. You can find contact information for many support companies and individuals in the file 'etc/SERVICE' in the GNU Emacs distribution. In any event, we also recommend that you submit bug reports for GDB. The preferred method is to submit them directly using GDB's Bugs web page (http://www.gnu.org/software/gdb/bugs/). Alternatively, the e-mail gateway can be used. *Do not send bug reports to 'info-gdb', or to 'help-gdb', or to any newsgroups.* Most users of GDB do not want to receive bug reports. Those that do have arranged to receive 'bug-gdb'. The mailing list 'bug-gdb' has a newsgroup 'gnu.gdb.bug' which serves as a repeater. The mailing list and the newsgroup carry exactly the same messages. Often people think of posting bug reports to the newsgroup instead of mailing them. This appears to work, but it has one problem which can be crucial: a newsgroup posting often lacks a mail path back to the sender. Thus, if we need to ask for more information, we may be unable to reach you. For this reason, it is better to send bug reports to the mailing list. The fundamental principle of reporting bugs usefully is this: *report all the facts*. If you are not sure whether to state a fact or leave it out, state it! Often people omit facts because they think they know what causes the problem and assume that some details do not matter. Thus, you might assume that the name of the variable you use in an example does not matter. Well, probably it does not, but one cannot be sure. Perhaps the bug is a stray memory reference which happens to fetch from the location where that name is stored in memory; perhaps, if the name were different, the contents of that location would fool the debugger into doing the right thing despite the bug. Play it safe and give a specific, complete example. That is the easiest thing for you to do, and the most helpful. Keep in mind that the purpose of a bug report is to enable us to fix the bug. It may be that the bug has been reported previously, but neither you nor we can know that unless your bug report is complete and self-contained. Sometimes people give a few sketchy facts and ask, "Does this ring a bell?" Those bug reports are useless, and we urge everyone to _refuse to respond to them_ except to chide the sender to report bugs properly. To enable us to fix the bug, you should include all these things: * The version of GDB. GDB announces it if you start with no arguments; you can also print it at any time using 'show version'. Without this, we will not know whether there is any point in looking for the bug in the current version of GDB. * The type of machine you are using, and the operating system name and version number. * The details of the GDB build-time configuration. GDB shows these details if you invoke it with the '--configuration' command-line option, or if you type 'show configuration' at GDB's prompt. * What compiler (and its version) was used to compile GDB--e.g. "gcc-2.8.1". * What compiler (and its version) was used to compile the program you are debugging--e.g. "gcc-2.8.1", or "HP92453-01 A.10.32.03 HP C Compiler". For GCC, you can say 'gcc --version' to get this information; for other compilers, see the documentation for those compilers. * The command arguments you gave the compiler to compile your example and observe the bug. For example, did you use '-O'? To guarantee you will not omit something important, list them all. A copy of the Makefile (or the output from make) is sufficient. If we were to try to guess the arguments, we would probably guess wrong and then we might not encounter the bug. * A complete input script, and all necessary source files, that will reproduce the bug. * A description of what behavior you observe that you believe is incorrect. For example, "It gets a fatal signal." Of course, if the bug is that GDB gets a fatal signal, then we will certainly notice it. But if the bug is incorrect output, we might not notice unless it is glaringly wrong. You might as well not give us a chance to make a mistake. Even if the problem you experience is a fatal signal, you should still say so explicitly. Suppose something strange is going on, such as, your copy of GDB is out of synch, or you have encountered a bug in the C library on your system. (This has happened!) Your copy might crash and ours would not. If you told us to expect a crash, then when ours fails to crash, we would know that the bug was not happening for us. If you had not told us to expect a crash, then we would not be able to draw any conclusion from our observations. To collect all this information, you can use a session recording program such as 'script', which is available on many Unix systems. Just run your GDB session inside 'script' and then include the 'typescript' file with your bug report. Another way to record a GDB session is to run GDB inside Emacs and then save the entire buffer to a file. * If you wish to suggest changes to the GDB source, send us context diffs. If you even discuss something in the GDB source, refer to it by context, not by line number. The line numbers in our development sources will not match those in your sources. Your line numbers would convey no useful information to us. Here are some things that are not necessary: * A description of the envelope of the bug. Often people who encounter a bug spend a lot of time investigating which changes to the input file will make the bug go away and which changes will not affect it. This is often time consuming and not very useful, because the way we will find the bug is by running a single example under the debugger with breakpoints, not by pure deduction from a series of examples. We recommend that you save your time for something else. Of course, if you can find a simpler example to report _instead_ of the original one, that is a convenience for us. Errors in the output will be easier to spot, running under the debugger will take less time, and so on. However, simplification is not vital; if you do not want to do this, report the bug anyway and send us the entire test case you used. * A patch for the bug. A patch for the bug does help us if it is a good one. But do not omit the necessary information, such as the test case, on the assumption that a patch is all we need. We might see problems with your patch and decide to fix the problem another way, or we might not understand it at all. Sometimes with a program as complicated as GDB it is very hard to construct an example that will make the program follow a certain path through the code. If you do not send us the example, we will not be able to construct one, so we will not be able to verify that the bug is fixed. And if we cannot understand what bug you are trying to fix, or why your patch should be an improvement, we will not install it. A test case will help us to understand. * A guess about what the bug is or what it depends on. Such guesses are usually wrong. Even we cannot guess right about such things without first using the debugger to find the facts.  File: gdb.info, Node: Command Line Editing, Next: Using History Interactively, Prev: GDB Bugs, Up: Top 32 Command Line Editing *********************** This chapter describes the basic features of the GNU command line editing interface. * Menu: * Introduction and Notation:: Notation used in this text. * Readline Interaction:: The minimum set of commands for editing a line. * Readline Init File:: Customizing Readline from a user's view. * Bindable Readline Commands:: A description of most of the Readline commands available for binding * Readline vi Mode:: A short description of how to make Readline behave like the vi editor.  File: gdb.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing 32.1 Introduction to Line Editing ================================= The following paragraphs describe the notation used to represent keystrokes. The text 'C-k' is read as 'Control-K' and describes the character produced when the key is pressed while the Control key is depressed. The text 'M-k' is read as 'Meta-K' and describes the character produced when the Meta key (if you have one) is depressed, and the key is pressed. The Meta key is labeled on many keyboards. On keyboards with two keys labeled (usually to either side of the space bar), the on the left side is generally set to work as a Meta key. The key on the right may also be configured to work as a Meta key or may be configured as some other modifier, such as a Compose key for typing accented characters. If you do not have a Meta or key, or another key working as a Meta key, the identical keystroke can be generated by typing _first_, and then typing . Either process is known as "metafying" the key. The text 'M-C-k' is read as 'Meta-Control-k' and describes the character produced by "metafying" 'C-k'. In addition, several keys have their own names. Specifically, , , , , , and all stand for themselves when seen in this text, or in an init file (*note Readline Init File::). If your keyboard lacks a key, typing will produce the desired character. The key may be labeled or on some keyboards.  File: gdb.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing 32.2 Readline Interaction ========================= Often during an interactive session you type in a long line of text, only to notice that the first word on the line is misspelled. The Readline library gives you a set of commands for manipulating the text as you type it in, allowing you to just fix your typo, and not forcing you to retype the majority of the line. Using these editing commands, you move the cursor to the place that needs correction, and delete or insert the text of the corrections. Then, when you are satisfied with the line, you simply press . You do not have to be at the end of the line to press ; the entire line is accepted regardless of the location of the cursor within the line. * Menu: * Readline Bare Essentials:: The least you need to know about Readline. * Readline Movement Commands:: Moving about the input line. * Readline Killing Commands:: How to delete text, and how to get it back! * Readline Arguments:: Giving numeric arguments to commands. * Searching:: Searching through previous lines.  File: gdb.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction 32.2.1 Readline Bare Essentials ------------------------------- In order to enter characters into the line, simply type them. The typed character appears where the cursor was, and then the cursor moves one space to the right. If you mistype a character, you can use your erase character to back up and delete the mistyped character. Sometimes you may mistype a character, and not notice the error until you have typed several other characters. In that case, you can type 'C-b' to move the cursor to the left, and then correct your mistake. Afterwards, you can move the cursor to the right with 'C-f'. When you add text in the middle of a line, you will notice that characters to the right of the cursor are 'pushed over' to make room for the text that you have inserted. Likewise, when you delete text behind the cursor, characters to the right of the cursor are 'pulled back' to fill in the blank space created by the removal of the text. A list of the bare essentials for editing the text of an input line follows. 'C-b' Move back one character. 'C-f' Move forward one character. or Delete the character to the left of the cursor. 'C-d' Delete the character underneath the cursor. Printing characters Insert the character into the line at the cursor. 'C-_' or 'C-x C-u' Undo the last editing command. You can undo all the way back to an empty line. (Depending on your configuration, the key be set to delete the character to the left of the cursor and the key set to delete the character underneath the cursor, like 'C-d', rather than the character to the left of the cursor.)  File: gdb.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction 32.2.2 Readline Movement Commands --------------------------------- The above table describes the most basic keystrokes that you need in order to do editing of the input line. For your convenience, many other commands have been added in addition to 'C-b', 'C-f', 'C-d', and . Here are some commands for moving more rapidly about the line. 'C-a' Move to the start of the line. 'C-e' Move to the end of the line. 'M-f' Move forward a word, where a word is composed of letters and digits. 'M-b' Move backward a word. 'C-l' Clear the screen, reprinting the current line at the top. Notice how 'C-f' moves forward a character, while 'M-f' moves forward a word. It is a loose convention that control keystrokes operate on characters while meta keystrokes operate on words.  File: gdb.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction 32.2.3 Readline Killing Commands -------------------------------- "Killing" text means to delete the text from the line, but to save it away for later use, usually by "yanking" (re-inserting) it back into the line. ('Cut' and 'paste' are more recent jargon for 'kill' and 'yank'.) If the description for a command says that it 'kills' text, then you can be sure that you can get the text back in a different (or the same) place later. When you use a kill command, the text is saved in a "kill-ring". Any number of consecutive kills save all of the killed text together, so that when you yank it back, you get it all. The kill ring is not line specific; the text that you killed on a previously typed line is available to be yanked back later, when you are typing another line. Here is the list of commands for killing text. 'C-k' Kill the text from the current cursor position to the end of the line. 'M-d' Kill from the cursor to the end of the current word, or, if between words, to the end of the next word. Word boundaries are the same as those used by 'M-f'. 'M-' Kill from the cursor the start of the current word, or, if between words, to the start of the previous word. Word boundaries are the same as those used by 'M-b'. 'C-w' Kill from the cursor to the previous whitespace. This is different than 'M-' because the word boundaries differ. Here is how to "yank" the text back into the line. Yanking means to copy the most-recently-killed text from the kill buffer. 'C-y' Yank the most recently killed text back into the buffer at the cursor. 'M-y' Rotate the kill-ring, and yank the new top. You can only do this if the prior command is 'C-y' or 'M-y'.  File: gdb.info, Node: Readline Arguments, Next: Searching, Prev: Readline Killing Commands, Up: Readline Interaction 32.2.4 Readline Arguments ------------------------- You can pass numeric arguments to Readline commands. Sometimes the argument acts as a repeat count, other times it is the sign of the argument that is significant. If you pass a negative argument to a command which normally acts in a forward direction, that command will act in a backward direction. For example, to kill text back to the start of the line, you might type 'M-- C-k'. The general way to pass numeric arguments to a command is to type meta digits before the command. If the first 'digit' typed is a minus sign ('-'), then the sign of the argument will be negative. Once you have typed one meta digit to get the argument started, you can type the remainder of the digits, and then the command. For example, to give the 'C-d' command an argument of 10, you could type 'M-1 0 C-d', which will delete the next ten characters on the input line.  File: gdb.info, Node: Searching, Prev: Readline Arguments, Up: Readline Interaction 32.2.5 Searching for Commands in the History -------------------------------------------- Readline provides commands for searching through the command history for lines containing a specified string. There are two search modes: "incremental" and "non-incremental". Incremental searches begin before the user has finished typing the search string. As each character of the search string is typed, Readline displays the next entry from the history matching the string typed so far. An incremental search requires only as many characters as needed to find the desired history entry. To search backward in the history for a particular string, type 'C-r'. Typing 'C-s' searches forward through the history. The characters present in the value of the 'isearch-terminators' variable are used to terminate an incremental search. If that variable has not been assigned a value, the and 'C-J' characters will terminate an incremental search. 'C-g' will abort an incremental search and restore the original line. When the search is terminated, the history entry containing the search string becomes the current line. To find other matching entries in the history list, type 'C-r' or 'C-s' as appropriate. This will search backward or forward in the history for the next entry matching the search string typed so far. Any other key sequence bound to a Readline command will terminate the search and execute that command. For instance, a will terminate the search and accept the line, thereby executing the command from the history list. A movement command will terminate the search, make the last line found the current line, and begin editing. Readline remembers the last incremental search string. If two 'C-r's are typed without any intervening characters defining a new search string, any remembered search string is used. Non-incremental searches read the entire search string before starting to search for matching history lines. The search string may be typed by the user or be part of the contents of the current line.  File: gdb.info, Node: Readline Init File, Next: Bindable Readline Commands, Prev: Readline Interaction, Up: Command Line Editing 32.3 Readline Init File ======================= Although the Readline library comes with a set of Emacs-like keybindings installed by default, it is possible to use a different set of keybindings. Any user can customize programs that use Readline by putting commands in an "inputrc" file, conventionally in his home directory. The name of this file is taken from the value of the environment variable 'INPUTRC'. If that variable is unset, the default is '~/.inputrc'. If that file does not exist or cannot be read, the ultimate default is '/etc/inputrc'. When a program which uses the Readline library starts up, the init file is read, and the key bindings are set. In addition, the 'C-x C-r' command re-reads this init file, thus incorporating any changes that you might have made to it. * Menu: * Readline Init File Syntax:: Syntax for the commands in the inputrc file. * Conditional Init Constructs:: Conditional key bindings in the inputrc file. * Sample Init File:: An example inputrc file.  File: gdb.info, Node: Readline Init File Syntax, Next: Conditional Init Constructs, Up: Readline Init File 32.3.1 Readline Init File Syntax -------------------------------- There are only a few basic constructs allowed in the Readline init file. Blank lines are ignored. Lines beginning with a '#' are comments. Lines beginning with a '$' indicate conditional constructs (*note Conditional Init Constructs::). Other lines denote variable settings and key bindings. Variable Settings You can modify the run-time behavior of Readline by altering the values of variables in Readline using the 'set' command within the init file. The syntax is simple: set VARIABLE VALUE Here, for example, is how to change from the default Emacs-like key binding to use 'vi' line editing commands: set editing-mode vi Variable names and values, where appropriate, are recognized without regard to case. Unrecognized variable names are ignored. Boolean variables (those that can be set to on or off) are set to on if the value is null or empty, ON (case-insensitive), or 1. Any other value results in the variable being set to off. A great deal of run-time behavior is changeable with the following variables. 'bell-style' Controls what happens when Readline wants to ring the terminal bell. If set to 'none', Readline never rings the bell. If set to 'visible', Readline uses a visible bell if one is available. If set to 'audible' (the default), Readline attempts to ring the terminal's bell. 'bind-tty-special-chars' If set to 'on', Readline attempts to bind the control characters treated specially by the kernel's terminal driver to their Readline equivalents. 'comment-begin' The string to insert at the beginning of the line when the 'insert-comment' command is executed. The default value is '"#"'. 'completion-display-width' The number of screen columns used to display possible matches when performing completion. The value is ignored if it is less than 0 or greater than the terminal screen width. A value of 0 will cause matches to be displayed one per line. The default value is -1. 'completion-ignore-case' If set to 'on', Readline performs filename matching and completion in a case-insensitive fashion. The default value is 'off'. 'completion-map-case' If set to 'on', and COMPLETION-IGNORE-CASE is enabled, Readline treats hyphens ('-') and underscores ('_') as equivalent when performing case-insensitive filename matching and completion. 'completion-prefix-display-length' The length in characters of the common prefix of a list of possible completions that is displayed without modification. When set to a value greater than zero, common prefixes longer than this value are replaced with an ellipsis when displaying possible completions. 'completion-query-items' The number of possible completions that determines when the user is asked whether the list of possibilities should be displayed. If the number of possible completions is greater than this value, Readline will ask the user whether or not he wishes to view them; otherwise, they are simply listed. This variable must be set to an integer value greater than or equal to 0. A negative value means Readline should never ask. The default limit is '100'. 'convert-meta' If set to 'on', Readline will convert characters with the eighth bit set to an ASCII key sequence by stripping the eighth bit and prefixing an character, converting them to a meta-prefixed key sequence. The default value is 'on'. 'disable-completion' If set to 'On', Readline will inhibit word completion. Completion characters will be inserted into the line as if they had been mapped to 'self-insert'. The default is 'off'. 'editing-mode' The 'editing-mode' variable controls which default set of key bindings is used. By default, Readline starts up in Emacs editing mode, where the keystrokes are most similar to Emacs. This variable can be set to either 'emacs' or 'vi'. 'echo-control-characters' When set to 'on', on operating systems that indicate they support it, readline echoes a character corresponding to a signal generated from the keyboard. The default is 'on'. 'enable-keypad' When set to 'on', Readline will try to enable the application keypad when it is called. Some systems need this to enable the arrow keys. The default is 'off'. 'enable-meta-key' When set to 'on', Readline will try to enable any meta modifier key the terminal claims to support when it is called. On many terminals, the meta key is used to send eight-bit characters. The default is 'on'. 'expand-tilde' If set to 'on', tilde expansion is performed when Readline attempts word completion. The default is 'off'. 'history-preserve-point' If set to 'on', the history code attempts to place the point (the current cursor position) at the same location on each history line retrieved with 'previous-history' or 'next-history'. The default is 'off'. 'history-size' Set the maximum number of history entries saved in the history list. If set to zero, the number of entries in the history list is not limited. 'horizontal-scroll-mode' This variable can be set to either 'on' or 'off'. Setting it to 'on' means that the text of the lines being edited will scroll horizontally on a single screen line when they are longer than the width of the screen, instead of wrapping onto a new screen line. By default, this variable is set to 'off'. 'input-meta' If set to 'on', Readline will enable eight-bit input (it will not clear the eighth bit in the characters it reads), regardless of what the terminal claims it can support. The default value is 'off'. The name 'meta-flag' is a synonym for this variable. 'isearch-terminators' The string of characters that should terminate an incremental search without subsequently executing the character as a command (*note Searching::). If this variable has not been given a value, the characters and 'C-J' will terminate an incremental search. 'keymap' Sets Readline's idea of the current keymap for key binding commands. Acceptable 'keymap' names are 'emacs', 'emacs-standard', 'emacs-meta', 'emacs-ctlx', 'vi', 'vi-move', 'vi-command', and 'vi-insert'. 'vi' is equivalent to 'vi-command'; 'emacs' is equivalent to 'emacs-standard'. The default value is 'emacs'. The value of the 'editing-mode' variable also affects the default keymap. 'mark-directories' If set to 'on', completed directory names have a slash appended. The default is 'on'. 'mark-modified-lines' This variable, when set to 'on', causes Readline to display an asterisk ('*') at the start of history lines which have been modified. This variable is 'off' by default. 'mark-symlinked-directories' If set to 'on', completed names which are symbolic links to directories have a slash appended (subject to the value of 'mark-directories'). The default is 'off'. 'match-hidden-files' This variable, when set to 'on', causes Readline to match files whose names begin with a '.' (hidden files) when performing filename completion. If set to 'off', the leading '.' must be supplied by the user in the filename to be completed. This variable is 'on' by default. 'menu-complete-display-prefix' If set to 'on', menu completion displays the common prefix of the list of possible completions (which may be empty) before cycling through the list. The default is 'off'. 'output-meta' If set to 'on', Readline will display characters with the eighth bit set directly rather than as a meta-prefixed escape sequence. The default is 'off'. 'page-completions' If set to 'on', Readline uses an internal 'more'-like pager to display a screenful of possible completions at a time. This variable is 'on' by default. 'print-completions-horizontally' If set to 'on', Readline will display completions with matches sorted horizontally in alphabetical order, rather than down the screen. The default is 'off'. 'revert-all-at-newline' If set to 'on', Readline will undo all changes to history lines before returning when 'accept-line' is executed. By default, history lines may be modified and retain individual undo lists across calls to 'readline'. The default is 'off'. 'show-all-if-ambiguous' This alters the default behavior of the completion functions. If set to 'on', words which have more than one possible completion cause the matches to be listed immediately instead of ringing the bell. The default value is 'off'. 'show-all-if-unmodified' This alters the default behavior of the completion functions in a fashion similar to SHOW-ALL-IF-AMBIGUOUS. If set to 'on', words which have more than one possible completion without any possible partial completion (the possible completions don't share a common prefix) cause the matches to be listed immediately instead of ringing the bell. The default value is 'off'. 'skip-completed-text' If set to 'on', this alters the default completion behavior when inserting a single match into the line. It's only active when performing completion in the middle of a word. If enabled, readline does not insert characters from the completion that match characters after point in the word being completed, so portions of the word following the cursor are not duplicated. For instance, if this is enabled, attempting completion when the cursor is after the 'e' in 'Makefile' will result in 'Makefile' rather than 'Makefilefile', assuming there is a single possible completion. The default value is 'off'. 'visible-stats' If set to 'on', a character denoting a file's type is appended to the filename when listing possible completions. The default is 'off'. Key Bindings The syntax for controlling key bindings in the init file is simple. First you need to find the name of the command that you want to change. The following sections contain tables of the command name, the default keybinding, if any, and a short description of what the command does. Once you know the name of the command, simply place on a line in the init file the name of the key you wish to bind the command to, a colon, and then the name of the command. There can be no space between the key name and the colon - that will be interpreted as part of the key name. The name of the key can be expressed in different ways, depending on what you find most comfortable. In addition to command names, readline allows keys to be bound to a string that is inserted when the key is pressed (a MACRO). KEYNAME: FUNCTION-NAME or MACRO KEYNAME is the name of a key spelled out in English. For example: Control-u: universal-argument Meta-Rubout: backward-kill-word Control-o: "> output" In the above example, 'C-u' is bound to the function 'universal-argument', 'M-DEL' is bound to the function 'backward-kill-word', and 'C-o' is bound to run the macro expressed on the right hand side (that is, to insert the text '> output' into the line). A number of symbolic character names are recognized while processing this key binding syntax: DEL, ESC, ESCAPE, LFD, NEWLINE, RET, RETURN, RUBOUT, SPACE, SPC, and TAB. "KEYSEQ": FUNCTION-NAME or MACRO KEYSEQ differs from KEYNAME above in that strings denoting an entire key sequence can be specified, by placing the key sequence in double quotes. Some GNU Emacs style key escapes can be used, as in the following example, but the special character names are not recognized. "\C-u": universal-argument "\C-x\C-r": re-read-init-file "\e[11~": "Function Key 1" In the above example, 'C-u' is again bound to the function 'universal-argument' (just as it was in the first example), ''C-x' 'C-r'' is bound to the function 're-read-init-file', and ' <[> <1> <1> <~>' is bound to insert the text 'Function Key 1'. The following GNU Emacs style escape sequences are available when specifying key sequences: '\C-' control prefix '\M-' meta prefix '\e' an escape character '\\' backslash '\"' <">, a double quotation mark '\'' <'>, a single quote or apostrophe In addition to the GNU Emacs style escape sequences, a second set of backslash escapes is available: '\a' alert (bell) '\b' backspace '\d' delete '\f' form feed '\n' newline '\r' carriage return '\t' horizontal tab '\v' vertical tab '\NNN' the eight-bit character whose value is the octal value NNN (one to three digits) '\xHH' the eight-bit character whose value is the hexadecimal value HH (one or two hex digits) When entering the text of a macro, single or double quotes must be used to indicate a macro definition. Unquoted text is assumed to be a function name. In the macro body, the backslash escapes described above are expanded. Backslash will quote any other character in the macro text, including '"' and '''. For example, the following binding will make ''C-x' \' insert a single '\' into the line: "\C-x\\": "\\"  File: gdb.info, Node: Conditional Init Constructs, Next: Sample Init File, Prev: Readline Init File Syntax, Up: Readline Init File 32.3.2 Conditional Init Constructs ---------------------------------- Readline implements a facility similar in spirit to the conditional compilation features of the C preprocessor which allows key bindings and variable settings to be performed as the result of tests. There are four parser directives used. '$if' The '$if' construct allows bindings to be made based on the editing mode, the terminal being used, or the application using Readline. The text of the test extends to the end of the line; no characters are required to isolate it. 'mode' The 'mode=' form of the '$if' directive is used to test whether Readline is in 'emacs' or 'vi' mode. This may be used in conjunction with the 'set keymap' command, for instance, to set bindings in the 'emacs-standard' and 'emacs-ctlx' keymaps only if Readline is starting out in 'emacs' mode. 'term' The 'term=' form may be used to include terminal-specific key bindings, perhaps to bind the key sequences output by the terminal's function keys. The word on the right side of the '=' is tested against both the full name of the terminal and the portion of the terminal name before the first '-'. This allows 'sun' to match both 'sun' and 'sun-cmd', for instance. 'application' The APPLICATION construct is used to include application-specific settings. Each program using the Readline library sets the APPLICATION NAME, and you can test for a particular value. This could be used to bind key sequences to functions useful for a specific program. For instance, the following command adds a key sequence that quotes the current or previous word in Bash: $if Bash # Quote the current or previous word "\C-xq": "\eb\"\ef\"" $endif '$endif' This command, as seen in the previous example, terminates an '$if' command. '$else' Commands in this branch of the '$if' directive are executed if the test fails. '$include' This directive takes a single filename as an argument and reads commands and bindings from that file. For example, the following directive reads from '/etc/inputrc': $include /etc/inputrc