declare smobs in alloc.c

[bpt/emacs.git] / etc / DEBUG

diff --git a/etc/DEBUG b/etc/DEBUG
index 20bdd6c..c1b04ea 100644 (file)
--- a/etc/DEBUG
+++ b/etc/DEBUG
@@ -1,6 +1,6 @@
 Debugging GNU Emacs
 
-Copyright (C) 1985, 2000-2012  Free Software Foundation, Inc.
+Copyright (C) 1985, 2000-2014 Free Software Foundation, Inc.
 See the end of the file for license conditions.
 
 
@@ -8,17 +8,30 @@ See the end of the file for license conditions.
 read the Windows-specific section near the end of this document.]
 
 ** When you debug Emacs with GDB, you should start it in the directory
-where the executable was made.  That directory has a .gdbinit file
-that defines various "user-defined" commands for debugging Emacs.
-(These commands are described below under "Examining Lisp object
-values" and "Debugging Emacs Redisplay problems".)
-
-** When you are trying to analyze failed assertions, it will be
-essential to compile Emacs either completely without optimizations or
-at least (when using GCC) with the -fno-crossjumping option.  Failure
-to do so may make the compiler recycle the same abort call for all
-assertions in a given function, rendering the stack backtrace useless
-for identifying the specific failed assertion.
+where the executable was made (the 'src' directory in the Emacs source
+tree).  That directory has a .gdbinit file that defines various
+"user-defined" commands for debugging Emacs.  (These commands are
+described below under "Examining Lisp object values" and "Debugging
+Emacs Redisplay problems".)
+
+Some GDB versions by default do not automatically load .gdbinit files
+in the directory where you invoke GDB.  With those versions of GDB,
+you will see a warning when GDB starts, like this:
+
+  warning: File ".../src/.gdbinit" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
+
+There are several ways to overcome that difficulty, they are all
+described in the node "Auto-loading safe path" in the GDB user manual.
+
+** When you are trying to analyze failed assertions or backtraces, it
+is essential to compile Emacs with flags suitable for debugging.
+With GCC 4.8 or later, you can invoke 'make' with CFLAGS="-Og -g3".
+With older GCC or non-GCC compilers, you can use CFLAGS="-O0 -g3".
+With GCC and higher optimization levels such as -O2, the
+-fno-omit-frame-pointer and -fno-crossjumping options are often
+essential.  The latter prevents GCC from using the same abort call for
+all assertions in a given function, rendering the stack backtrace
+useless for identifying the specific failed assertion.
 
 ** It is a good idea to run Emacs under GDB (or some other suitable
 debugger) *all the time*.  Then, when Emacs crashes, you will be able
@@ -758,4 +771,3 @@ Local variables:
 mode: outline
 paragraph-separate: "[         \f]*$"
 end:
-