On 05/27/2011 12:47 AM, Thomas Bushnell, BSG wrote: > I just noticed that the mtdev source I've been looking at is Debian > unstable, which is a tad newer than natty, and in particular, adds an > additional safety check in the front of mtdev_open. If indeed a null > pointer is passed in to mtdev_open's first arg, it would quickly > segfault (though I can't see why the fault would be in mtdev_open and > not mtdev_init). > > I wonder if this might not be the immediate cause of the crash. I don't > know how to quickly get the natty source for evdev (with the patches to > call mtdev from Chase Douglas); the Debian unstable version of evdev > does not yet include that patch. From the one I see > (http://lists.x.org/archives/xorg-devel/2011-January/018405.html) this > shouldn't happen: > > The dev could only be bad if EvdevOpenDevice were to have pEvdev->device > set, but pEvdev->mtdev still unset. That can't happen afaict, though I > would prefer the patch initialized mtdev in a separate branch to make > that clearer. > > Still, I'm interested to know if the patch to check the args to > mtdev_open was prompted by actual problems or just general cleanup. > > It is also odd to me that the crash is reported to be at mtdev_open+22, > but according to gdb, that's in the middle of an instruction, and if the > PC got pointed there by mistake, its a register-only instruction anyhow, > so it can't fault.
Hi Thomas, I've read all your emails, but I'm preplexed as well as to why X is crashing. I don't believe any new mtdev code was added for any specific reason other than general cleanups, and I've not heard of anyone else encountering such a bug. If you can attach to it through gdb, you could step through the mtdev_open call to see which line is causing a segfault. You may find it helpful to build a test package of xserver-xorg-input-evdev without optimizations by setting the env var DEB_BUILD_OPTIONS="noopt". Please file a bug for this in Launchpad, and subscribe the utouch-bugs team. Thanks! -- Chase -- Ubuntu-installer mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-installer
