Fer's blog
fer, ferulo, that crazy man

Sun, 30 Sep 2007

And breakpad is almost here

This week I went insane while debugging some obscure crash in ARM + glib + logging + threads. Finding this kind of stuff on glibc scares me:

/* Atomic compare and exchange.  These sequences are not actually atomic;
   there is a race if *MEM != OLDVAL and we are preempted between the two
   swaps.  However, they are very close to atomic, and are the best that a
   pre-ARMv6 implementation can do without operating system support.
   LinuxThreads has been using these sequences for many years.  */
at least, it's documented :)
On the other hand I got enough energy for some very low-level hacking and finally got DWARF2 symbols dumping for breakpad/bug-buddy minidumps! The bad news are that it's a _ugly_ hack on top of valgrind code, trying to de-valgrinize (and bastardazing it while doing it). However it works, and should be enough for our target in GNOME for having rich backtraces coming from people without debugging symbols and enriching them in the debug server. Also the socorro server is prepared for deployment with our (GNOME) custom modifications and nice and beautiful features:

Did I hear eye-candy? transparency? No, this is just about reading the _real_ code crashing :)
Here are the bits:
git-clone http://www.gnome.org/~fherrera/dumper.git
git-clone http://www.gnome.org/~fherrera/socorro.git
git-clone http://www.gnome.org/~fherrera/bug-buddy.git
Currently, if you want to test it you'd need to point bug-buddy to my home server or if you are brave enough, run your own socorro collector. Ah, I also started using git :)
Finally the last open issue to get all of this working are the package collectors: a simple piece of code that has to:And that's all. I'll probably start working on a RPM based one this week, but of course all your help is highly appreciated

[17:27] | Permalink | 5 comments

Posted by Luis at Sun Sep 30 17:27:27 2007

Posted by Ray Strode at Sun Sep 30 21:46:32 2007
Hey, awesome news, fer!  Keep up the great work.

Posted by Ted Mielczarek at Tue Oct 9 23:25:48 2007
Awesome!  Looking forward to getting more people interested in the Socorro code!

Posted by Federico Castanedo at Fri Oct 19 16:26:37 2007
Wow Fer!, there is no bugs for you. Take Care!

Posted by Eero Tamminen at Wed Dec 5 22:27:16 2007
Instead of hacking something on top of valgrind code, why not use libunwind? Frysk people are adding separate debug symbol files .debug_frame section support to it.

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Fernando Herrera

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