Debugging i3: How To
====================
Michael Stapelberg <michael@i3wm.org>
-February 2012
+January 2014
-This document describes how to debug i3 suitably for sending us useful bug
-reports, even if you have no clue of C programming.
+This document describes how to debug i3 to send us useful bug
+reports, even if you have no knowledge of C programming.
-First of all: Thank you for being interested in debugging i3. It really means
+Thank you for being interested in debugging i3. It really means
something to us to get your bug fixed. If you have any questions about the
-debugging and/or need further help, do not hesitate to contact us!
+process and/or need further help, do not hesitate to contact us!
-== Verify you are using the latest (development) version
+== Verify you are using i3 ≥ 4.7
-Please verify that you are using the latest version of i3:
+Only the latest major version of i3 is supported, i.e. version 4.7 currently.
+To verify which version you are running, use:
---------------
-$ i3 --version
-i3 version 4.1.2-248-g51728ba (2012-02-12, branch "next")
+$ i3 --moreversion
+Binary i3 version: 4.7 (2013-12-22, branch "tags/4.7")
+Running i3 version: 4.7-84-gac74a63 (2014-01-01, branch "next") (pid 1995)
---------------
Your version can look like this:
-4.1.2::
-You are using a release version. Please
-upgrade to a development version first, or read
-link:debugging-release-version.html[Debugging i3: How To (release version)].
+4.7 (release version)::
+You are using a release version. In many cases, bugs are already
+fixed in the development version of i3. Even if the bug is not a known fixed
+one, we will still ask you to reproduce your error with the most recent
+development version of i3. Therefore, please upgrade to a development version
+if you can.
-4.1.2-248-g51728ba::
-Your version is 248 commits newer than 4.1.2, and the git revision of your
-version is +51728ba+. Go to http://code.i3wm.org/i3/commit/?h=next and see if
+4.7-85-g9c15b95 (development version)::
+Your version is 85 commits newer than 4.7, and the git revision of your
+version is +9c15b95+. Go to http://code.i3wm.org/i3/commit/?h=next and see if
the line "commit" starts with the same revision. If so, you are using the
latest version.
-Development versions of i3 have several properties which make debugging easier:
+Development versions of i3 have logging enabled by default and are compiled
+with debug symbols.
-1. Shared memory debug logging is enabled by default. You do not have to enable
- logging explicitly.
-2. Core dumps are enabled by default.
-3. If you are using a version from the Debian/Ubuntu autobuilder, it is
- compiled without optimization. Debug symbols are available in the i3-wm-dbg
- package. When compiling i3 yourself, debug mode is the default.
+== Enabling logging
+
+If you are using a development version (see previous section), you don’t need
+to do anything -- skip to section 3.
+
+If you are using a release version with a custom +~/.xsession+ (or xinitrc)
+file, execute i3 with a line like this:
+
+----------------------------------
+# Use 25 MiB of RAM for debug logs
+exec i3 --shmlog-size=26214400
+----------------------------------
+
+If you are *NOT* using an +~/.xsession+ file but you just chose "i3" from the
+list of sessions in your desktop manager (gdm, lxdm, …), edit
++/usr/share/xsessions/i3.desktop+ and replace the +Exec=i3+ line with:
+
+------------------------------
+Exec=i3 --shmlog-size=26214400
+------------------------------
+
+If you cannot restart i3 for some reason, you can enable debug logging on the
+fly:
+
+---------------------------------------
+i3-msg 'debuglog on; shmlog on; reload'
+---------------------------------------
== Obtaining the debug logfile
To save a compressed version of the logfile (suitable for attaching it to a
bugreport), use:
--------------------------------------------------------------------
-i3-dump-log | gzip -9c > /tmp/i3.log.gz
+DISPLAY=:0 i3-dump-log | bzip2 -c > /tmp/i3.log.bz2
--------------------------------------------------------------------
-This command does not depend on i3 (it also works when i3 currently displays
-the crash dialog), but it requires a working X11 connection. When running it
-from a virtual console (Ctrl-Alt-F1), use:
+This command does not depend on i3 (it also works while i3 displays
+the crash dialog), but it requires a working X11 connection.
---------------------------------------------------------------------
-DISPLAY=:0 i3-dump-log | gzip -9c > /tmp/i3.log.gz
---------------------------------------------------------------------
+== Compiling with debug symbols
-== Obtaining a backtrace
+To actually get useful backtraces, you should make sure that your version of i3
+is compiled with debug symbols:
+
+------------------------------------------------------------------------------
+$ file `which i3`
+/usr/bin/i3: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically
+linked (uses shared libs), for GNU/Linux 2.6.18, not stripped
+------------------------------------------------------------------------------
-When i3 displays its crash dialog, do the following:
+Notice the +not stripped+, which is the important part. If you have a version
+which is stripped, please check whether your distribution provides debug
+symbols (package +i3-wm-dbg+ on Debian for example) or if you can turn off
+stripping. If nothing helps, please build i3 from source.
-1. Switch to a virtual console (Ctrl-Alt-F1) or login from a different computer
-2. Generate a backtrace (see below)
-3. Switch back to the crash dialog (Ctrl-Alt-F7)
-4. Restart i3 in-place (you will keep your session), continue working
+== Obtaining a backtrace
-This is how you get a backtrace from a running i3 process:
+Once you have made sure that your i3 is compiled with debug symbols and the C
+debugger +gdb+ is installed on your machine, you can let i3 generate a
+backtrace in the crash dialog.
------------------
-I3PID=$(pidof i3)
-gdb /proc/$I3PID/exe $I3PID \
- --batch --quiet \
- --ex 'backtrace full' > /tmp/i3-backtrace.txt 2>&1
------------------
+After pressing "b" in the crash dialog, you will get a file called
++/tmp/i3-backtrace.%d.%d.txt+ where the first +%d+ is replaced by i3’s process
+id (PID) and the second one is incremented each time you generate a backtrace,
+starting at 0.
== Sending bug reports/debugging on IRC
projects / i3 / i3 / blobdiff