I think this theory has some legs. I had noticed some apparently random characters showing up on VT7 after stopping gdm manually during debugging.
I've now restarted the PC several times, not touched the keyboard until the gdm log-in screen appears. Select the user with the mouse and then begin typing the password. After 3 characters xserver crashes and restarts.
Use another tty to "sudo stop gdm" then Ctrl+Alt+F7. Once VT7 text console is revealed it shows a few kernel log messages from the drm driver (see bug #342122 "[i815] [drm:drm_release] *ERROR* reclaim_buffers_locked() deadlock") but, more importantly, there's some *quasi-random* characters appearing and, in most cases, they are the same across reboots - suggesting they are generated.
They look to be partial control-code representations.
I think this theory has some legs. I had noticed some apparently random characters showing up on VT7 after stopping gdm manually during debugging.
I've now restarted the PC several times, not touched the keyboard until the gdm log-in screen appears. Select the user with the mouse and then begin typing the password. After 3 characters xserver crashes and restarts.
Use another tty to "sudo stop gdm" then Ctrl+Alt+F7. Once VT7 text console is revealed it shows a few kernel log messages from the drm driver (see bug #342122 "[i815] [drm:drm_release] *ERROR* reclaim_ buffers_ locked( ) deadlock") but, more importantly, there's some *quasi-random* characters appearing and, in most cases, they are the same across reboots - suggesting they are generated.
They look to be partial control-code representations.
E.g: " ^X ^C ]^]^]^] ^]^]^]888888888 888888888888888 88 8888888888;
or: ^]^]^]^
The latter happens if, as soon as the log-in dialog appears, I switch away to VT1 (Ctrl+Alt+F1), log-in, then "sudo stop gdm" and then Ctrl+Alt+F7.
If I stop the gdm process from a remote ssh session these characters don't show up.