Commit 3a817827 authored by Eli Zaretskii's avatar Eli Zaretskii

Add explanation of how to debug with GDB starting from the Emacs Abort dialog.

parent c95dddbe
......@@ -243,7 +243,19 @@
You should be able to debug Emacs using the debugger that is
appropriate for the compiler you used, namely DevStudio or Windbg if
compiled with MSVC, or gdb if compiled with gcc.
compiled with MSVC, or GDB if compiled with GCC.
When Emacs aborts due to a fatal internal error, Emacs on Windows
pops up an Emacs Abort Dialog asking you whether you want to debug
Emacs or terminate it. If Emacs was built with MSVC, click YES
twice, and Windbg or the DevStudio debugger will start up
automatically. If Emacs was built with GCC, first start GDB and
attach it to the Emacs process with the "gdb -p EMACS-PID" command,
where EMACS-PID is the Emacs process ID (which you can see in the
Windows Task Manager), type the "continue" command inside GDB, and
only then click YES on the abort dialog. This will pass control to
the debugger, and you will be able to debug the cause of the fatal
error.
Emacs functions implemented in C use a naming convention that reflects
their names in lisp. The names of the C routines are the lisp names
......@@ -254,17 +266,18 @@
easily set breakpoints or examine familiar lisp variables by name.
Since Emacs data is often in the form of a lisp object, and the
Lisp_Object type is difficult to examine manually in the MSVC
debugger, Emacs provides a helper routine called debug_print that
prints out a readable representation of a Lisp_Object. (If you are
using gdb, there is a .gdbinit file in the src directory which
provides definitions that are useful for examining lisp objects. The
following tips are mainly of interest when using MSVC.) The output
from debug_print is sent to stderr, and to the debugger via the
OutputDebugString routine. The output sent to stderr should be
displayed in the console window that was opened when the emacs.exe
executable was started. The output sent to the debugger should be
displayed in its "Debug" output window.
Lisp_Object type is difficult to examine manually in a debugger,
Emacs provides a helper routine called debug_print that prints out a
readable representation of a Lisp_Object. If you are using GDB,
there is a .gdbinit file in the src directory which provides
definitions that are useful for examining lisp objects. Therefore,
the following tips are mainly of interest when using MSVC.
The output from debug_print is sent to stderr, and to the debugger
via the OutputDebugString routine. The output sent to stderr should
be displayed in the console window that was opened when the
emacs.exe executable was started. The output sent to the debugger
should be displayed in its "Debug" output window.
When you are in the process of debugging Emacs and you would like to
examine the contents of a Lisp_Object variable, popup the QuickWatch
......
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