ubuntu-x-swat team mailing list archive

[Seth <625239@xxxxxxxxxxxxxxxxxx>]

Ok, joining here by Gruber's request from #532047. I have temporarily
removed my workaround from my comment #91 there, so I'm testing against
a 'standard' lucid install on a very fast booting system with i386
generic-pae, 8Gb RAM, Q9550 and nvidia-current.

(a) adding plymouth:debug affects timing enough to stop the problem from occurring (all my X sessions in 4 reboots ended up on vt7).
(b) removed the plymouth:debug again
(c) next reboot, my disks got fsck-ed - no problem (timing issue, once again)
(d) next reboot my X session ends up on tty3. I can see the -isig flag with 'stty -F /dev/tty3'. I can safely hit enter in the greeter. I did not login.
(e) Instead, I help fate a little by doing 'stty -F /dev/tty3 isig' from the vt1, then switch to vt3 and press the '2' key. Lo and behold: immediate X crash (this is the first time I witnessed a crash from another trigger key than enter, I think). After the crash, X is relaunched on tty8

(f) another reboot, X session ends up on tty3 again and I start entering
this comment. Upon entering the thrid digit of the bug number reference
(a '2') the X session vanishes. Much cursing ensues :) and I relogin to
start over. Note that I did not notice the scrolllock light as a
premonition this time (it might not be deterministic).

So no real news, other than a heap of confirmations for you:

(A) vt allocation race is a root cause
(B) enter as well as '2' key can crash the session if vt is 'armed' (+isig)
(C) scroll lock premonition is not deterministic
(D) vt allocation is not deterministic (varies from vt2, vt3 mostly to vt7 on 'slow boot' with any delaying option or event)

Last but not least, I noticed (again) that on changing to vt1 for the analysis steps, some of the time my primary display's output would be garbled. Changing back and forth a few times would show several different distortions, until finally the output becomes ok across both displays. I'm not sure whether the 'garbling' occurs if X was on vt7 from the start. Also, I don't know, if this could be related and if it was related, whether the nvidia driver might be _causing_ some of the effects here, or whether the vt allocation issues are _causing_ the nvidia driver to have trouble when switching vts. 
I just thought I'd mention it because (for the first time) I thought it might actually be related. I have noticed occasional text console garbling (large block characters, random pixel noise in bright colours and other issues). Perhaps someone recognizes that behaviour?

So I'm sorry I cannot post any useful plymouth-debug.log. I'm not sure
whether you're interested in an actual ps listing, or whether you were
simply after the above tty numbers? (I use 'ps -ef | grep X' to see
them).

PS. Just thought of attaching the Xorg.0.log from when the X session was
crashed with the '2' key. I couldn't find the actual log (the log file
naming convention seems magic to me), so I'll make a new one and post it
later

-- 
X starts on wrong tty: pressing enter after 5 minutes crashes X
https://bugs.launchpad.net/bugs/625239
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