on the flag to output ^M at the end of each line. You can fix the
problem by adding this to your .cshrc file:
- if ($?EMACS) then
- if ("$EMACS" =~ /*) then
- unset edit
- stty -icrnl -onlcr -echo susp ^Z
- endif
+ if ($?INSIDE_EMACS && $?tcsh)
+ unset edit
+ stty -icrnl -onlcr -echo susp ^Z
endif
*** Emacs startup on GNU/Linux systems (and possibly other systems) is slow.
can cause this error. Remove that file, execute 'ispell-kill-ispell'
in Emacs, and then try spell-checking again.
+*** Emacs eats all file descriptors when using kqueue file notifications.
+See <http://debbugs.gnu.org/22814>.
+
+When you have a large number of buffers running auto-revert-mode, and
+Emacs is configured to use the kqueue file notification library, it
+uses an own file descriptor for every watched file. On systems with a
+small limit of file descriptors allowed per process, like OS X, you
+could run out of file descriptors. You won't be able to open new files.
+
+auto-revert-use-notify is set to nil in global-auto-revert-mode, therefore.
+
* Runtime problems related to font handling
** Characters are displayed as empty boxes or with wrong font under X.
** Window-manager and toolkit-related problems
+*** Emacs built with GTK+ toolkit produces corrupted display on HiDPI screen
+
+This can happen if you set GDK_SCALE=2 in the environment or in your
+'.xinitrc' file. (This setting is usually accompanied by
+GDK_DPI_SCALE=0.5.) Emacs can not support these settings correctly,
+as it doesn't use GTK+ exclusively. The result is that sometimes
+widgets like the scroll bar are displayed incorrectly, and frames
+could be displayed "cropped" to only part of the stuff that should be
+displayed.
+
+The workaround is to explicitly disable these settings when invoking
+Emacs, for example (from a Posix shell prompt):
+
+ $ GDK_SCALE=1 GDK_DPI_SCALE=1 emacs
+
*** Metacity: Resizing Emacs or ALT-Tab causes X to be unresponsive.
This happens sometimes when using Metacity. Resizing Emacs or ALT-Tab:bing
the 'xmodmap' utility to show all the keys which produce a Meta
modifier:
- xmodmap -pk | egrep -i "meta|alt"
+ xmodmap -pk | grep -Ei "meta|alt"
A more convenient way of finding out which keys produce a Meta modifier
is to use the 'xkbprint' utility, if it's available on your system:
A workaround is to build Emacs with MinGW runtime 3.x (the latest
version is 3.20).
+** addpm fails to run on Windows NT4, complaining about Shell32.dll
+
+This is likely to happen because Shell32.dll shipped with NT4 lacks
+the updates required by Emacs. Installing Internet Explorer 4 solves
+the problem. Note that it is NOT enough to install IE6, because doing
+so will not install the Shell32.dll update.
+
** A few seconds delay is seen at startup and for many file operations
This happens when the Net Logon service is enabled. During Emacs
of Windows. This is caused by a deficiency in the underlying system
library function.
-** Problems with set-time-zone-rule function
+** Non-US time zones.
-The function set-time-zone-rule gives incorrect results for many
-non-US timezones. This is due to over-simplistic handling of
-daylight savings switchovers by the Windows libraries.
+Many non-US time zones are implemented incorrectly. This is due to
+over-simplistic handling of daylight savings switchovers by the
+Windows libraries.
** Files larger than 4GB report wrong size in a 32-bit Windows build
** Dumping
-*** Segfault during 'make bootstrap' under the Linux kernel.
+*** Segfault during 'make'
-In Red Hat Linux kernels, "Exec-shield" functionality is enabled by
-default, which creates a different memory layout that can break the
-emacs dumper. Emacs tries to handle this at build time, but if this
-fails, the following instructions may be useful.
+If Emacs segfaults when 'make' executes one of these commands:
-Exec-shield is enabled on your system if
+ LC_ALL=C ./temacs -batch -l loadup bootstrap
+ LC_ALL=C ./temacs -batch -l loadup dump
- cat /proc/sys/kernel/exec-shield
+the problem may be due to inadequate workarounds for address space
+layout randomization (ASLR), an operating system feature that
+randomizes the virtual address space of a process. ASLR is commonly
+enabled in Linux and NetBSD kernels, and is intended to deter exploits
+of pointer-related bugs in applications. If ASLR is enabled, the
+command:
-prints a value other than 0. (Please read your system documentation
-for more details on Exec-shield and associated commands.)
+ cat /proc/sys/kernel/randomize_va_space # GNU/Linux
+ sysctl security.pax.aslr.global # NetBSD
-Additionally, Linux kernel versions since 2.6.12 randomize the virtual
-address space of a process by default. If this feature is enabled on
-your system, then
+outputs a nonzero value.
- cat /proc/sys/kernel/randomize_va_space
+These segfaults should not occur on most modern systems, because the
+Emacs build procedure uses the command 'setfattr' or 'paxctl' to mark
+the Emacs executable as requiring non-randomized address space, and
+Emacs uses the 'personality' system call to disable address space
+randomization when dumping. However, older kernels may not support
+'setfattr', 'paxctl', or 'personality', and newer Linux kernels have a
+secure computing mode (seccomp) that can be configured to disable the
+'personality' call.
-prints a value other than 0.
+It may be possible to work around the 'personality' problem in a newer
+Linux kernel by configuring seccomp to allow the 'personality' call.
+For example, if you are building Emacs under Docker, you can run the
+Docker container with a security profile that allows 'personality' by
+using Docker's --security-opt option with an appropriate profile; see
+<https://docs.docker.com/engine/security/seccomp/>.
-When these features are enabled, building Emacs may segfault during
-the execution of this command:
+To work around the ASLR problem in either an older or a newer kernel,
+you can temporarily disable the feature while building Emacs. On
+GNU/Linux you can do so using the following command (as root).
- ./temacs --batch --load loadup [dump|bootstrap]
+ echo 0 > /proc/sys/kernel/randomize_va_space
-To work around this problem, you can temporarily disable these
-features while building Emacs. You can do so using the following
-commands (as root). Remember to re-enable them when you are done,
-by echoing the original values back to the files.
+You can re-enable the feature when you are done, by echoing the
+original value back to the file. NetBSD uses a different command,
+e.g., 'sysctl -w security.pax.aslr.global=0'.
- echo 0 > /proc/sys/kernel/exec-shield
- echo 0 > /proc/sys/kernel/randomize_va_space
+Alternatively, you can try using the 'setarch' command when building
+temacs like this, where -R disables address space randomization:
+
+ setarch $(uname -m) -R make
-Or, on x86, you can try using the 'setarch' command when running
-temacs, like this:
+ASLR is not the only problem that can break Emacs dumping. Another
+issue is that in Red Hat Linux kernels, Exec-shield is enabled by
+default, and this creates a different memory layout. Emacs should
+handle this at build time, but if this fails the following
+instructions may be useful. Exec-shield is enabled on your system if
- setarch i386 -R ./temacs --batch --load loadup [dump|bootstrap]
+ cat /proc/sys/kernel/exec-shield
-or
+prints a nonzero value. You can temporarily disable it as follows:
- setarch i386 -R make
+ echo 0 > /proc/sys/kernel/exec-shield
-(The -R option disables address space randomization.)
+As with randomize_va_space, you can re-enable Exec-shield when you are
+done, by echoing the original value back to the file.
*** temacs prints "Pure Lisp storage exhausted".