Known Problems with GNU Emacs
-Copyright (C) 1987-1989, 1993-1999, 2001-2011
- Free Software Foundation, Inc.
+Copyright (C) 1987-1989, 1993-1999, 2001-2013 Free Software Foundation,
+Inc.
See the end of the file for license conditions.
CFLAGS="-g -O2 -fno-optimize-sibling-calls" ./configure
+** Emacs compiled with GCC 4.6.1 crashes on MS-Windows when C-g is pressed
+
+This is known to happen when Emacs is compiled with MinGW GCC 4.6.1
+with the -O2 option (which is the default in the Windows build). The
+reason is a bug in MinGW GCC 4.6.1; to work around, either add the
+`-fno-omit-frame-pointer' switch to GCC or compile without
+optimizations (`--no-opt' switch to the configure.bat script).
+
** Emacs crashes in x-popup-dialog.
This can happen if the dialog widget cannot find the font it wants to
If you need Emacs to be able to recover from closing displays, compile
it with the Lucid toolkit instead of GTK.
+** Emacs crashes when you try to view a file with complex characters.
+For example, the etc/HELLO file (as shown by C-h h).
+The message "symbol lookup error: /usr/bin/emacs: undefined symbol: OTF_open"
+is shown in the terminal from which you launched Emacs.
+This problem only happens when you use a graphical display (ie not
+with -nw) and compiled Emacs with the "libotf" library for complex
+text handling.
+
+This problem occurs because unfortunately there are two libraries
+called "libotf". One is the library for handling OpenType fonts,
+http://www.m17n.org/libotf/, which is the one that Emacs expects.
+The other is a library for Open Trace Format, and is used by some
+versions of the MPI message passing interface for parallel
+programming.
+
+For example, on RHEL6 GNU/Linux, the OpenMPI rpm provides a version
+of "libotf.so" in /usr/lib/openmpi/lib. This directory is not
+normally in the ld search path, but if you want to use OpenMPI,
+you must issue the command "module load openmpi". This adds
+/usr/lib/openmpi/lib to LD_LIBRARY_PATH. If you then start Emacs from
+the same shell, you will encounter this crash.
+Ref: <URL:https://bugzilla.redhat.com/show_bug.cgi?id=806031>
+
+There is no good solution to this problem if you need to use both
+OpenMPI and Emacs with libotf support. The best you can do is use a
+wrapper shell script (or function) "emacs" that removes the offending
+element from LD_LIBRARY_PATH before starting emacs proper.
+Or you could recompile Emacs with an -Wl,-rpath option that
+gives the location of the correct libotf.
+
* General runtime problems
** Lisp problems
** Keyboard problems
+*** Unable to enter the M-| key on some German keyboards.
+Some users have reported that M-| suffers from "keyboard ghosting".
+This can't be fixed by Emacs, as the keypress never gets passed to it
+at all (as can be verified using "xev"). You can work around this by
+typing `ESC |' instead.
+
*** "Compose Character" key does strange things when used as a Meta key.
If you define one key to serve as both Meta and Compose Character, you
the `flock' system call. The other involves creating a lock file;
`movemail' must be able to write in /usr/spool/mail in order to do
this. You control which one is used by defining, or not defining,
-the macro MAIL_USE_FLOCK in config.h or the m- or s- file it includes.
+the macro MAIL_USE_FLOCK in config.h.
IF YOU DON'T USE THE FORM OF INTERLOCKING THAT IS NORMAL ON YOUR
SYSTEM, YOU CAN LOSE MAIL!
#define LIBS_SYSTEM -lresolv
Then if this gives you an error for redefining a macro, and you see that
-the s- file defines LIBS_SYSTEM as -lfoo -lbar, you could change config.h
-again to say this:
+config.h already defines LIBS_SYSTEM as -lfoo -lbar at some other point
+(possibly in an included file) you could change it to say this:
#define LIBS_SYSTEM -lresolv -lfoo -lbar
** Miscellaneous problems
+*** Editing files with very long lines is slow.
+
+For example, simply moving through a file that contains hundreds of
+thousands of characters per line is slow, and consumes a lot of CPU.
+This is a known limitation of Emacs with no solution at this time.
+
*** Emacs uses 100% of CPU time
This is a known problem with some versions of the Semantic package.
4) Use lbxproxy on the remote end of the connection. This is an interface
to the low bandwidth X extension in most modern X servers, which
improves performance dramatically, at the slight expense of correctness
- of the X protocol. lbxproxy acheives the performance gain by grouping
+ of the X protocol. lbxproxy achieves the performance gain by grouping
several X requests in one TCP packet and sending them off together,
instead of requiring a round-trip for each X request in a separate
packet. The switches that seem to work best for emacs are:
Option "Device" "/dev/input/mice"
EndSection
+*** Emacs is slow to exit in X
+
+After you use e.g. C-x C-c to exit, it takes many seconds before the
+Emacs window disappears. If Emacs was started from a terminal, you
+see the message:
+
+ Error saving to X clipboard manager.
+ If the problem persists, set `x-select-enable-clipboard-manager' to nil.
+
+As the message suggests, this problem occurs when Emacs thinks you
+have a clipboard manager program running, but has trouble contacting it.
+If you don't want to use a clipboard manager, you can set the
+suggested variable. Or you can make Emacs not wait so long by
+reducing the value of `x-selection-timeout', either in .emacs or with
+X resources.
+
+Sometimes this problem is due to a bug in your clipboard manager.
+Updating to the latest version of the manager can help.
+For example, in the Xfce 4.8 desktop environment, the clipboard
+manager in versions of xfce4-settings-helper before 4.8.2 is buggy;
+https://bugzilla.xfce.org/show_bug.cgi?id=7588 .
+
* Runtime problems on character terminals
** The meta key does not work on xterm.
global-font-lock-mode RET" or by customizing the variable
`global-font-lock-mode'.
+** Unexpected characters inserted into the buffer when you start Emacs.
+See eg http://debbugs.gnu.org/11129
+
+This can happen when you start Emacs in -nw mode in an Xterm.
+For example, in the *scratch* buffer, you might see something like:
+
+ 0;276;0c
+
+This is more likely to happen if you are using Emacs over a slow
+connection, and begin typing before Emacs is ready to respond.
+
+This occurs when Emacs tries to query the terminal to see what
+capabilities it supports, and gets confused by the answer.
+To avoid it, set xterm-extra-capabilities to a value other than
+`check' (the default). See that variable's documentation (in
+term/xterm.el) for more details.
+
* Runtime problems specific to individual Unix variants
** GNU/Linux
with +t bit, the directory owner becomes the owner of the symbolic
link, so that it cannot be removed by anyone else.
-If you don't like those useless links, you can let Emacs not to using
-file lock by adding #undef CLASH_DETECTION to config.h.
+If you don't like those useless links, you can customize
+the option `create-lockfiles'.
*** FreeBSD: Getting a Meta key on the console.
built in editor to print (this is possibly the only useful purpose it
has):
-(setq printer-name "") ;; notepad takes the default
-(setq lpr-command "notepad") ;; notepad
-(setq lpr-switches nil) ;; not needed
-(setq lpr-printer-switch "/P") ;; run notepad as batch printer
+(setq printer-name "") ; notepad takes the default
+(setq lpr-command "notepad") ; notepad
+(setq lpr-switches nil) ; not needed
+(setq lpr-printer-switch "/P") ; run notepad as batch printer
** Antivirus software interacts badly with the MS-Windows version of Emacs.
*** The dumped Emacs crashes when run, trying to write pure data.
-Two causes have been seen for such problems.
-
-1) On a system where getpagesize is not a system call, it is defined
+On a system where getpagesize is not a system call, it is defined
as a macro. If the definition (in both unex*.c and malloc.c) is wrong,
it can cause problems like this. You might be able to find the correct
value in the man page for a.out (5).
-2) Some systems allocate variables declared static among the
-initialized variables. Emacs makes all initialized variables in most
-of its files pure after dumping, but the variables declared static and
-not initialized are not supposed to be pure. On these systems you
-may need to add "#define static" to the m- or the s- file.
-
* Runtime problems on legacy systems
This section covers bugs reported on very old hardware or software.
pen@lysator.liu.se says (Feb 1998) that the Compose key does work
if you link with the MIT X11 libraries instead of the Solaris X11 libraries.
-*** HP/UX 10: Large file support is disabled.
-(HP/UX 10 was end-of-lifed in May 1999.)
-See the comments in src/s/hpux10-20.h.
-
*** HP/UX: Emacs is slow using X11R5.
This happens if you use the MIT versions of the X libraries--it
This seems to be due to a GCC bug; it is fixed in GCC 2.8.1.
-** Vax C compiler bugs affecting Emacs.
-
-You may get one of these problems compiling Emacs:
-
- foo.c line nnn: compiler error: no table entry for op STASG
- foo.c: fatal error in /lib/ccom
-
-These are due to bugs in the C compiler; the code is valid C.
-Unfortunately, the bugs are unpredictable: the same construct
-may compile properly or trigger one of these bugs, depending
-on what else is in the source file being compiled. Even changes
-in header files that should not affect the file being compiled
-can affect whether the bug happens. In addition, sometimes files
-that compile correctly on one machine get this bug on another machine.
-
-As a result, it is hard for me to make sure this bug will not affect
-you. I have attempted to find and alter these constructs, but more
-can always appear. However, I can tell you how to deal with it if it
-should happen. The bug comes from having an indexed reference to an
-array of Lisp_Objects, as an argument in a function call:
- Lisp_Object *args;
- ...
- ... foo (5, args[i], ...)...
-putting the argument into a temporary variable first, as in
- Lisp_Object *args;
- Lisp_Object tem;
- ...
- tem = args[i];
- ... foo (r, tem, ...)...
-causes the problem to go away.
-The `contents' field of a Lisp vector is an array of Lisp_Objects,
-so you may see the problem happening with indexed references to that.
-
-** 68000 C compiler problems
-
-Various 68000 compilers have different problems.
-These are some that have been observed.
-
-*** Using value of assignment expression on union type loses.
-This means that x = y = z; or foo (x = z); does not work
-if x is of type Lisp_Object.
-
-*** "cannot reclaim" error.
-
-This means that an expression is too complicated. You get the correct
-line number in the error message. The code must be rewritten with
-simpler expressions.
-
-*** XCONS, XSTRING, etc macros produce incorrect code.
-
-If temacs fails to run at all, this may be the cause.
-Compile this test program and look at the assembler code:
-
-struct foo { char x; unsigned int y : 24; };
-
-lose (arg)
- struct foo arg;
-{
- test ((int *) arg.y);
-}
-
-If the code is incorrect, your compiler has this problem.
-In the XCONS, etc., macros in lisp.h you must replace (a).u.val with
-((a).u.val + coercedummy) where coercedummy is declared as int.
-
-This problem will only happen if USE_LISP_UNION_TYPE is manually
-defined in lisp.h.
-
-** C compilers lose on returning unions.
-
-I hear that some C compilers cannot handle returning a union type.
-Most of the functions in GNU Emacs return type Lisp_Object, which is
-defined as a union on some rare architectures.
-
-This problem will only happen if USE_LISP_UNION_TYPE is manually
-defined in lisp.h.
-
\f
This file is part of GNU Emacs.