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@ -1,42 +1,36 @@
~~Title: Enlightenment debugging~~
==== Enlightenment Debugging ===
==== Enlightenment Debugging ====
This tutorial aims at providing a comprehensive and reproducible documentation
to debug Enlightenment. It is divided in two sections:
* [[enlightenment_debugging#Debugging_Enlightenment_using_Gdb|Gdb]]
* [[enlightenment_debugging#Valgrind|Valgrind]]
This tutorial aims at providing a comprehensive and reproducible documentation to debug Enlightenment. It is divided in two sections:
Before debugging make sure your debug symbols are enabled, if not, go to the
[[/docs-efl-start#Enable_debug_symbols_Optional|Enable debug symbols]]
section.
* [[#Debugging_Enlightenment_using_GDB|GDB]]
* [[#Valgrind|Valgrind]]
Before debugging make sure your debug symbols are enabled, if not, go to the [[/docs-efl-start#Enable_debug_symbols_Optional|Enable debug symbols]] section.
=== Debugging Enlightenment using Gdb ===
=== Debugging Enlightenment using GDB ===
In order to use gdb, we will simulate a crash in Enlightenment.
In order to use GDB, we will simulate a crash in Enlightenment.
Start by running Enlightenment on a machine. Then switch to another tty
(CTRL+ALT+F1 for tty1).
Start by running Enlightenment on a machine. Then switch to another tty (CTRL+ALT+F1 for tty1).
At that point, 2 processes are interesting, enlightenment and
enlightenment_start. Indeed, enlightenment is traced by enlightenment_start.
At that point, 2 processes are interesting, ''enlightenment'' and ''enlightenment_start''. Indeed, ''enlightenment'' is traced by ''enlightenment_start''.
Then setup SEGV to segfault enlightenment.
<code c>
kill -SIGSEGV $(pidof enlightenment)
</code>
enlightenment_start will open a pop-up named Enlightenment Error.
This pop-up indicates that Enlightenment segfaulted and allows to recover or
log out but also detaches from the child process (enlightenment) and let
advanced users use gdb to debug it.
''enlightenment_start will'' open a pop-up named Enlightenment Error. This pop-up indicates that Enlightenment segfaulted and allows to recover or log out but also detaches from the child process (Enlightenment) and let advanced users use GDB to debug it.
<code bash>
#gdb on the running enlightenment process
gdb enlightenment $(pidof enlightenment)
</code>
After a bit a prompt is available, if you want, you can save the
traces in a log:
After a bit a prompt is available, if you want, you can save the traces in a log:
<code bash>
#save the traces in log.txt
set logging file log.txt
@ -45,8 +39,7 @@ set logging on
== Backtrace ==
Use the backtrace command to get information about frames to
know where the segfault is coming from.
Use the backtrace command to get information about frames to know where the segfault is coming from.
<code bash>
(gdb) bt
@ -74,21 +67,13 @@ know where the segfault is coming from.
#12 0x08059bb3 in main (argc=1, argv=0xbffff144) at e_main.c:551
</code>
As you can see in the stack trace, gdb finds the segfault in libc and pops to the
main function in e_main. But it doesn't seem credible to have a bug in libc or
x, the important thing is Enlightenment has its own segfault handler which is
very explicit on frame 5.
As you can see in the stack trace, GDB finds the segfault in libc and pops to the main function in e_main. But it doesn't seem credible to have a bug in libc or x, the important thing is Enlightenment has its own segfault handler which is very explicit on frame 5.
The e_sigseg_act() function at frame 6 is called directly from the kernel when
the program segfaults, meaning enlightenment causes the
segfault. So, the
segfault comes from the select function (a libc function) at frame 8 called in
_e_core_main_select_function at frame 9.
The e_sigseg_act() function at frame 6 is called directly from the kernel when the program segfaults, meaning enlightenment causes the segfault. So, the segfault comes from the select function (a libc function) at frame 8 called in _e_core_main_select_function at frame 9.
== Go in a frame ==
So, the reason of segfault seems to be at frame 9, when //select// function is
called. Let's go to frame 9:
So, the reason of segfault seems to be at frame 9, when ''select'' function is called. Let's go to frame 9:
<code bash>
fr 9
@ -107,11 +92,7 @@ fr 9
342 }
</code>
The first command **//fr 9//** gives useful information: name of the file,
number of the line, the function called, ...
The second command **//l//** lists the code around the called function.
Another useful command allows to print the variables, the parameters, helping
you to find out the problem, a wrong parameter, a null pointer,...
The first command **//fr 9//** gives useful information: name of the file, number of the line, the function called, ... The second command **//l//** lists the code around the called function. Another useful command allows to print the variables, the parameters, helping you to find out the problem, a wrong parameter, a null pointer...
<code bash>
(gdb) p ret
@ -124,34 +105,27 @@ $3 = {__fds_bits = {0 <repeats 32 times>}}
$4 = {__fds_bits = {0 <repeats 32 times>}}
</code>
Gdb is important to start debugging, it will help you to resize the problem
even if sometimes is not enough.
GDB is important to start debugging, it will help you to resize the problem even if sometimes is not enough.
----
=== Valgrind ===
Valgrind aims at finding memory problems but for that Enlightenment needs to be run
through Valgrind.
Valgrind aims at finding memory problems but for that Enlightenment needs to be run through Valgrind.
== Prerequisites ==
This tutorial will present 3 different ways to run enlightenment through valgrind:
* remote debugging
This tutorial will present 3 different ways to run enlightenment through Valgrind:
* Remote debugging
* Xephyr invocation
* Xinit invocation
The easiest way is certainly Xephyr because it allows to target a window on a
X server host, sadly Xephyr doesn't yet support OpenGL and any issue that may
be related to it will need to use the Xinit version.
The easiest way is certainly Xephyr because it allows to target a window on a X server host, sadly Xephyr doesn't yet support OpenGL and any issue that may be related to it will need to use the Xinit version.
== Remote Debugging ==
Enlightenment_start launcher will handle
setting up environment variables, paths, and launching any other required
services before Enlightenment starts.
Fortunately, there are some options in enlightenment_start that allow to run
Enlightenment through valgrind:
Enlightenment_start launcher will handle setting up environment variables, paths, and launching any other required services before Enlightenment starts. Fortunately, there are some options in enlightenment_start that allow to run Enlightenment through Valgrind:
<code bash>
$enlightenment_start --help
@ -171,7 +145,7 @@ Options:
Save valgrind log to file, see valgrind's --log-f
</code>
First of all, get the ip address of your host machine and connect to it, then
First of all, get the IP address of your host machine and connect to it, then
on the distant machine, launch X:
<code bash>
@ -179,15 +153,14 @@ on the distant machine, launch X:
sudo X -ac :1 &
</code>
For example, If you want to check leak and save traces in a log file :
For example, if you want to check leak and save traces in a log file:
<code bash>
export DISPLAY=:1
enlightenment_start -valgrind=4 -valgrind-log-file=log.txt
</code>
At that point, Enlightenment should have started on your host machine. If the
session is closed then the summary of valgrind should look like :
At that point, Enlightenment should have started on your host machine. If the session is closed then the summary of Valgrind should look like:
<code bash>
==1488==
@ -207,7 +180,7 @@ session is closed then the summary of valgrind should look like :
==1488== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
</code>
== Valgrind Invocation - xinit ==
== Valgrind Invocation - Xinit ==
Create a file called .xinitrc-debug in your home with the following content:
@ -233,8 +206,7 @@ echo "PATH=$enlightenment_install_path/bin: ... " >> $log_file
$enlightenment_install_path/bin/enlightenment_start -valgrind 2>&1 | tee -a "$log_file"
</code>
You can now start a debugging session, after X was closed if it is not the
case log out:
You can now start a debugging session, after X was closed if it is not the case log out:
<code bash>
/usr/bin/xinit ~/.xinitrc-debug -- :1 -nolisten tcp
@ -242,23 +214,21 @@ case log out:
== Valgrind Invocation - Xephyr ==
Xephyr is a display server implementing the X11 display server protocol which
targets a window on a X Server host. So, for this it is important that X is
launched, you can even do it in your usual window manager under X.
Xephyr is a display server implementing the X11 display server protocol which targets a window on a X Server host. So, for this it is important that X is launched, you can even do it in your usual window manager under X.
Of course, you need to install Xephyr.
<code bash>
Xephyr -ac -br -noreset -screen 800x600 :1
</code>
*ac: disable access control restrictions
*br: create root window with black background
*noreset: don't reset after last client exists
*screen 800x600: Specify screen characteristics
A black screen should now be displayed, and the interesting thing for us is
that you can launch a window manager on it with valgrind in addition:
A black screen should now be displayed, and the interesting thing for us is that you can launch a window manager on it with Valgrind in addition:
<code bash>
DISPLAY=:1 enlightenment_start -valgrind
</code>
</code>