reformat docs/debugging

This commit is contained in:
Michael Stapelberg 2010-03-10 13:01:27 +01:00
parent 5d4d9681a0
commit 593bff5ffd
1 changed files with 45 additions and 39 deletions

View File

@ -3,19 +3,20 @@ Debugging i3: How To
Michael Stapelberg <michael+i3@stapelberg.de>
April 2009
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 suitably for sending us useful bug
reports, even if you have no clue of C programming.
First of all: 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!
First of all: 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!
== Enabling logging
i3 spits out much information onto stdout. To have a clearly defined place where logfiles
will be saved, you should redirect stdout and stderr in xsession. While youre at it,
putting each run of i3 in a separate logfile with date/time in it is a good idea to not
get confused about the different logfiles later on.
i3 spits out much information onto stdout. To have a clearly defined place
where logfiles will be saved, you should redirect stdout and stderr in
xsession. While youre at it, putting each run of i3 in a separate logfile with
date/time in it is a good idea to not get confused about the different logfiles
later on.
--------------------------------------------------------------------
exec /usr/bin/i3 >/home/michael/i3/i3log-$(date +'%F-%k-%M-%S') 2>&1
@ -23,32 +24,35 @@ exec /usr/bin/i3 >/home/michael/i3/i3log-$(date +'%F-%k-%M-%S') 2>&1
== Enabling coredumps
When i3 crashes, often you have the chance of getting a coredump (an image of the memory
of the i3 process which can be loaded into a debugger). To get a core-dump, you have to
make sure that the user limit for core dump files is set high enough. Many systems ship
with a default value which even forbids core dumps completely. To disable the limit
completely and thus enable coredumps, use the following command (in your .xsession, before
starting i3):
When i3 crashes, often you have the chance of getting a coredump (an image of
the memory of the i3 process which can be loaded into a debugger). To get a
core-dump, you have to make sure that the user limit for core dump files is set
high enough. Many systems ship with a default value which even forbids core
dumps completely. To disable the limit completely and thus enable coredumps,
use the following command (in your .xsession, before starting i3):
-------------------
ulimit -c unlimited
-------------------
Furthermore, to easily recognize core dumps and allow multiple of them, you should set
a custom core dump filename pattern, using a command like the following:
Furthermore, to easily recognize core dumps and allow multiple of them, you
should set a custom core dump filename pattern, using a command like the
following:
---------------------------------------------
sudo sysctl -w kernel.core_pattern=core.%e.%p
---------------------------------------------
This will generate files which have the executables file name (%e) and the process id
(%p) in it. You can save this setting across reboots using +/etc/sysctl.conf+.
This will generate files which have the executables file name (%e) and the
process id (%p) in it. You can save this setting across reboots using
+/etc/sysctl.conf+.
== Compiling with debug symbols
To actually get useful coredumps, you should make sure that your version of i3 is compiled
with debug symbols, that is, that they are not stripped during the build process. You
can check whether your executable contains symbols by issuing the following command:
To actually get useful coredumps, you should make sure that your version of i3
is compiled with debug symbols, that is, that they are not stripped during the
build process. You can check whether your executable contains symbols by
issuing the following command:
----------------
file $(which i3)
@ -60,23 +64,23 @@ You should get an output like this:
linked (uses shared libs), for GNU/Linux 2.6.18, not stripped
------------------------------------------------------------------------------
Notice the +not stripped+, which is the important part. If you have a version which is
stripped, please have a look if 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.
Notice the +not stripped+, which is the important part. If you have a version
which is stripped, please have a look if 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.
== Generating a backtrace
Once you have made sure that your i3 is compiled with debug symbols and that coredumps
are enabled, you can start getting some sense out of the coredumps.
Once you have made sure that your i3 is compiled with debug symbols and that
coredumps are enabled, you can start getting some sense out of the coredumps.
Because the coredump depends on the original executable (and its debug symbols), please
do this as soon as you encounter the problem. If you re-compile i3, your coredump might
be useless afterwards.
Because the coredump depends on the original executable (and its debug
symbols), please do this as soon as you encounter the problem. If you
re-compile i3, your coredump might be useless afterwards.
Please install +gdb+, a debugger for C. No worries, you dont need to learn it now.
Start gdb using the following command (replacing the actual name of the coredump of
course):
Please install +gdb+, a debugger for C. No worries, you dont need to learn it
now. Start gdb using the following command (replacing the actual name of the
coredump of course):
----------------------------
gdb $(which i3) core.i3.3849
@ -90,9 +94,11 @@ backtrace full
== Sending bugreports/debugging on IRC
When sending bugreports, please paste the relevant part of the log (if in doubt, please send us rather
too much information than too less) and the whole backtrace (if there was a coredump).
When sending bugreports, please paste the relevant part of the log (if in
doubt, please send us rather too much information than too less) and the whole
backtrace (if there was a coredump).
When debugging with us in IRC, be prepared to use a so called nopaste service such as http://nopaste.info
because pasting large amounts of text in IRC sometimes leads to incomplete lines (servers have line
length limitations) or flood kicks.
When debugging with us in IRC, be prepared to use a so called nopaste service
such as http://nopaste.info because pasting large amounts of text in IRC
sometimes leads to incomplete lines (servers have line length limitations) or
flood kicks.