122 lines
4.7 KiB
Plaintext
122 lines
4.7 KiB
Plaintext
Debugging i3: How To
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====================
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Michael Stapelberg <michael@i3wm.org>
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January 2014
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This document describes how to debug i3 to send us useful bug
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reports, even if you have no knowledge of C programming.
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Thank you for being interested in debugging i3. It really means
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something to us to get your bug fixed. If you have any questions about the
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process and/or need further help, do not hesitate to contact us!
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== Verify you are using i3 ≥ 4.7
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Only the latest major version of i3 is supported, i.e. version 4.7 currently.
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To verify which version you are running, use:
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---------------
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$ i3 --moreversion
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Binary i3 version: 4.7 (2013-12-22, branch "tags/4.7")
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Running i3 version: 4.7-84-gac74a63 (2014-01-01, branch "next") (pid 1995)
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---------------
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Your version can look like this:
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4.7 (release version)::
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You are using a release version. In many cases, bugs are already
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fixed in the development version of i3. Even if the bug is not a known fixed
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one, we will still ask you to reproduce your error with the most recent
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development version of i3. Therefore, please upgrade to a development version
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if you can.
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4.7-85-g9c15b95 (development version)::
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Your version is 85 commits newer than 4.7, and the git revision of your
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version is +9c15b95+. Go to http://code.i3wm.org/i3/commit/?h=next and see if
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the line "commit" starts with the same revision. If so, you are using the
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latest version.
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Development versions of i3 have logging enabled by default and are compiled
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with debug symbols.
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== Enabling logging
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If you are using a development version (see previous section), you don’t need
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to do anything -- skip to section 3.
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If you are using a release version with a custom +~/.xsession+ (or xinitrc)
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file, execute i3 with a line like this:
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----------------------------------
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# Use 25 MiB of RAM for debug logs
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exec i3 --shmlog-size=26214400
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----------------------------------
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If you are *NOT* using an +~/.xsession+ file but you just chose "i3" from the
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list of sessions in your desktop manager (gdm, lxdm, …), edit
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+/usr/share/xsessions/i3.desktop+ and replace the +Exec=i3+ line with:
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------------------------------
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Exec=i3 --shmlog-size=26214400
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------------------------------
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If you cannot restart i3 for some reason, you can enable debug logging on the
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fly:
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---------------------------------------
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i3-msg 'debuglog on; shmlog on; reload'
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---------------------------------------
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== Obtaining the debug logfile
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No matter whether i3 misbehaved in some way without crashing or whether it just
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crashed, the logfile provides all information necessary to debug the problem.
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To save a compressed version of the logfile (suitable for attaching it to a
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bugreport), use:
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--------------------------------------------------------------------
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DISPLAY=:0 i3-dump-log | bzip2 -c > /tmp/i3.log.bz2
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--------------------------------------------------------------------
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This command does not depend on i3 (it also works while i3 displays
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the crash dialog), but it requires a working X11 connection.
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== On crashes: Obtaining a backtrace
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When i3 crashes, it will display a dialog stating “i3 just crashed”, offering
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you to save a backtrace to a text file.
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To actually get useful backtraces, you should make sure that your version of i3
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is compiled with debug symbols:
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------------------------------------------------------------------------------
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$ file `which i3`
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/usr/bin/i3: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically
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linked (uses shared libs), for GNU/Linux 2.6.18, not stripped
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------------------------------------------------------------------------------
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Notice the +not stripped+, which is the important part. If you have a version
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which is stripped, please check whether your distribution provides debug
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symbols (package +i3-wm-dbg+ on Debian for example) or if you can turn off
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stripping. If nothing helps, please build i3 from source.
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Once you have made sure that your i3 is compiled with debug symbols and the C
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debugger +gdb+ is installed on your machine, you can let i3 generate a
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backtrace in the crash dialog.
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After pressing "b" in the crash dialog, you will get a file called
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+/tmp/i3-backtrace.%d.%d.txt+ where the first +%d+ is replaced by i3’s process
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id (PID) and the second one is incremented each time you generate a backtrace,
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starting at 0.
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== Sending bug reports/debugging on IRC
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When sending bug reports, please attach the *whole* log file. Even if you think
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you found the section which clearly highlights the problem, additional
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information might be necessary to completely diagnose the problem.
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When debugging with us in IRC, be prepared to use a so called nopaste service
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such as http://nopaste.info or http://pastebin.com because pasting large
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amounts of text in IRC sometimes leads to incomplete lines (servers have line
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length limitations) or flood kicks.
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