* Source Buffers:: Use the mouse in the fringe/margin to
control your program.
* Breakpoints Buffer:: A breakpoint control panel.
-* Threads Buffer:: Displays your threads.
* Stack Buffer:: Select a frame from the call stack.
* Other GDB-UI Buffers:: Input/output, locals, registers,
assembler, threads and memory buffers.
* Watch Expressions:: Monitor variable values in the speedbar.
-* Multithreaded Debugging:: Debugging programs with several threads.
+* Reverse Debugging:: Execute and reverse debug your program.
@end menu
@node GDB-UI Layout
|--------------------------------+--------------------------------+
| Primary Source buffer | I/O buffer for debugged pgm |
|--------------------------------+--------------------------------+
-| Stack buffer | Breakpoints/Thread buffer |
+| Stack buffer | Breakpoints/Threads buffer |
+--------------------------------+--------------------------------+
@end group
@end smallexample
Visit the source line for the breakpoint you click on.
@end table
-@vindex gdb-show-threads-by-default
When @code{gdb-many-windows} is non-@code{nil}, the breakpoints buffer
shares its window with the threads buffer. To switch from one to the
other click with @kbd{Mouse-1} on the relevant button in the header
-line, or press @kbd{TAB} inside that buffer. If
-@code{gdb-show-threads-by-default} is non-@code{nil}, the threads
-buffer, rather than the breakpoints buffer, is shown at start up.
-
-@node Threads Buffer
-@subsubsection Threads Buffer
-
-@findex gdb-select-thread
-The threads buffer displays a summary of all threads currently in your
-program (@pxref{Threads, Threads, Debugging programs with multiple
-threads, gdb, The GNU debugger}). Move point to any thread in the list
-and press @key{RET} to select it (@code{gdb-select-thread}) and
-display the associated source in the primary source buffer.
-Alternatively, click @kbd{Mouse-2} on a thread to select it. Contents
-of all GDB buffers are updated whenever you select a thread.
-
- You can customize variables under @code{gdb-buffers} group to select
-fields included in threads buffer.
-
-@table @code
-@item gdb-thread-buffer-verbose-names
-@vindex gdb-thread-buffer-verbose-names
-Show long thread names like @samp{Thread 0x4e2ab70 (LWP 1983)} in
-threads buffer.
-
-@item gdb-thread-buffer-arguments
-@vindex gdb-thread-buffer-arguments
-Show arguments of thread top frames in threads buffer.
-
-@item gdb-thread-buffer-locations
-@vindex gdb-thread-buffer-locations
-Show file information or library names in threads buffer.
-
-@item gdb-thread-buffer-addresses
-@vindex gdb-thread-buffer-addresses
-Show addresses for thread frames in threads buffer.
-@end table
-
- It’s possible to observe information for several threads
-simultaneously (in addition to buffers which show information for
-currently selected thread) using the following keys from the threads
-buffer.
-
-@table @kbd
-@item d
-@kindex d @r{(GDB threads buffer)}
-@findex gdb-display-disassembly-for-thread
-Display disassembly buffer for the thread at current line.
-(@code{gdb-display-disassembly-for-thread})
-
-@item f
-@kindex f @r{(GDB threads buffer)}
-@findex gdb-display-stack-for-thread
-Display stack buffer for the thread at current line.
-(@code{gdb-display-stack-for-thread}).
-
-@item l
-@kindex l @r{(GDB threads buffer)}
-@findex gdb-display-locals-for-thread
-Display locals buffer for the thread at current line.
-(@code{gdb-display-locals-for-thread}).
-
-@item r
-@kindex r @r{(GDB threads buffer)}
-@findex gdb-display-registers-for-thread
-Display registers buffer for the thread at current line.
-(@code{gdb-display-registers-for-thread}).
-@end table
-
-Pressing their upper-case counterparts, @kbd{D}, @kbd{F} ,@kbd{L} and
-@kbd{R} displays the corresponding buffer in a new frame.
-
- When you create a buffer showing information about some specific
-thread, it becomes bound to that thread and keeps showing actual
-information while you debug your program. Every GDB buffer contains a
-number of thread it shows information for in its mode name. Thread
-number is also included in the buffer name of bound buffers to prevent
-buffer names clashing.
-
-Further commands are available in the threads buffer which depend on the
-mode of GDB that is used for controlling execution of your program.
-(@pxref{Multithreaded Debugging, Stopping and Starting Multi-threaded Programs}).
+line.
@node Stack Buffer
@subsubsection Stack Buffer
@item Locals Buffer
The locals buffer displays the values of local variables of the
current frame for simple data types (@pxref{Frame Info, Frame Info,
-Information on a frame, gdb, The GNU debugger}). Press @key{RET} or
+Information on a frame, gdb, The GNU debugger}). Press @key{RET} or
click @kbd{Mouse-2} on the value if you want to edit it.
Arrays and structures display their type only. With GDB 6.4 or later,
press @key{SPC} to toggle the display of floating point registers
(@code{toggle-gdb-all-registers}).
-@item Disassembly Buffer
-The disassembly buffer displays the current frame as machine code. An
+@item Assembler Buffer
+The assembler buffer displays the current frame as machine code. An
arrow points to the current instruction, and you can set and remove
breakpoints as in a source buffer. Breakpoint icons also appear in
the fringe or margin.
+@item Threads Buffer
+@findex gdb-threads-select
+The threads buffer displays a summary of all threads currently in your
+program (@pxref{Threads, Threads, Debugging programs with multiple
+threads, gdb, The GNU debugger}). Move point to any thread in the
+list and press @key{RET} to select it (@code{gdb-threads-select}) and
+display the associated source in the primary source buffer.
+Alternatively, click @kbd{Mouse-2} on a thread to select it. If the
+locals buffer is visible, its contents update to display the variables
+that are local in the new thread.
+
+When there is more than one main thread and the threads buffer is
+present, Emacs displays the selected thread number in the mode line of
+many of the GDB-UI Buffers.
+
@item Memory Buffer
The memory buffer lets you examine sections of program memory
(@pxref{Memory, Memory, Examining memory, gdb, The GNU debugger}).
When @code{gdb-many-windows} is non-@code{nil}, the threads buffer
shares its window with the breakpoints buffer, and the locals buffer
-with the registers buffer. To switch from one to the other click with
-@kbd{Mouse-1} on the relevant button in the header line or press
-@kbd{TAB} inside the buffer.
+with the registers buffer. To switch from one to the other click with
+@kbd{Mouse-1} on the relevant button in the header line.
@node Watch Expressions
@subsubsection Watch Expressions
non-@code{nil}. This can be useful if you are debugging with a full
screen Emacs frame.
-@node Multithreaded Debugging
-@subsubsection Stopping and Starting Multi-threaded Programs
-@cindex Multithreaded debugging in GDB
-
-@subsubheading All-stop Debugging
-
-In all-stop mode, whenever your program stops, @emph{all} threads of
-execution stop. Likewise, whenever you restart the program, all
-threads start executing. @xref{All-Stop Mode, , All-Stop Mode, gdb,
-The GNU debugger}. You can enable this behaviour in Emacs by setting
-@code{gdb-non-stop-setting} to @code{nil} before starting a debugging
-session.
-
-@subsubheading Non-stop Debugging
-@cindex Non-stop debugging in GDB
-
-For some multi-threaded targets, GDB supports a further mode of
-operation in which you can examine stopped program threads in the
-debugger while other threads continue to execute freely.
-@xref{Non-Stop Mode, , Non-Stop Mode, gdb, The GNU debugger}.
-This is referred to as @dfn{non-stop} mode.
-
-Versions of GDB prior to 7.0 do not support non-stop mode and it does
-not work on all targets. In such cases, Emacs uses all-stop mode
-regardless of the value of @code{gdb-non-stop-setting}.
-
-@vindex gdb-non-stop-setting
-If the variable @code{gdb-non-stop-setting} is non-@code{nil} (the
-default value), Emacs tries to start GDB in non-stop mode. Note that
-GDB debugging session needs to be restarted for change of this setting
-to take effect.
-
-@vindex gdb-switch-when-another-stopped
-When a thread stops in non-stop mode, Emacs automatically switches to
-that thread. It may be undesirable to allow switching of current
-thread when some other stopped thread is already selected. Set
-@code{gdb-switch-when-another-stopped} to @code{nil} to prevent this.
-
-@vindex gdb-switch-reasons
-Emacs can decide whether or not to switch to the stopped thread
-depending on the reason which caused the stop. Customize
-@code{gdb-switch-reasons} to select stop reasons which make Emacs
-switch thread.
-
-@vindex gdb-stopped-hooks
-The variable @code{gdb-stopped-hooks} allows you to execute your
-functions whenever some thread stops.
-
- In non-stop mode, you can switch between different modes for GUD
-execution control commands.
-
-@vindex gdb-gud-control-all-threads
-@table @dfn
-@item Non-stop/A
-
-When @code{gdb-gud-control-all-threads} is @code{t} (the default
-value), interruption and continuation commands apply to all threads,
-so you can halt or continue all your threads with one command using
-@code{gud-stop-subjob} and @code{gud-cont}, respectively. The
-@samp{Go} button is shown on the toolbar when at least one thread is
-stopped, whereas @samp{Stop} button is shown when at least one thread
-is running.
-
-@item Non-stop/T
-
-When @code{gdb-gud-control-all-threads} is @code{nil}, only the
-current thread is stopped/continued. @samp{Go} and @samp{Stop}
-buttons on the GUD toolbar are shown depending on the state of current
-thread.
-@end table
-
-You can change the current value of @code{gdb-gud-control-all-threads}
-from the tool bar or from @samp{GUD->GDB-MI} menu.
-
- Stepping commands always apply to the current thread.
-
-@subsubheading Fine Thread Control
-
- In non-stop mode, you can interrupt/continue your threads without
-selecting them. Hitting @kbd{i} in threads buffer interrupts thread
-under point, @kbd{c} continues it, @kbd{s} steps through. More such
-commands may be added in the future.
-
-Combined with creating bound buffers for any thread, this allows you
-to change and track state of many threads in the same time.
-
- Note that when you interrupt a thread, it stops with @samp{signal
-received} reason. If that reason is included in your
-@code{gdb-switch-reasons} (it is by default), Emacs will switch to
-that thread.
+@node Reverse Debugging
+@subsubsection Reverse Debugging
+
+ The GDB tool bar shares many buttons with the other GUD debuggers
+for tasks like stepping and printing expressions. It also has a
+further set of buttons that allow reverse debugging (@pxref{Process
+Record and Replay, , ,gdb, The GNU debugger}). This is useful when it
+takes a long time to reproduce the conditions where your program fails
+or for transient problems, like race conditions in multi-threaded
+programs, where a failure might otherwise be hard to reproduce.
+
+To use reverse debugging, set a breakpoint slightly before the
+location of interest and run your program to that point. Enable
+process recording by clicking on the record button. At this point, a
+new set of buttons appear. These buttons allow program execution in
+the reverse direction. Run your program over the code where the
+problem occurs, and then use the new set of buttons to retrace your
+steps, examine values, and analyze the problem. When analysis is
+complete, turn off process recording by clicking on the record button
+again.
@node Executing Lisp
@section Executing Lisp Expressions
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