Created attachment 100275 [details]
log from dmesg

apparently starting with mesa-10.2rc4 with my 9800gt PCI-E on gnome-3.12.2

I get this errors:
[ 1340.694566] nouveau E[   PFIFO][0000:01:00.0] DMA_PUSHER - ch 2 [Xorg[630]]
get 0x0020023700 put 0x0020023710 ib_get 0x000002da ib_put 0x0000032f state
0x80000240 (err: INVALID_CMD) push 0x00406040
[ 2965.025771] nouveau E[   PFIFO][0000:01:00.0] DMA_PUSHER - ch 2 [Xorg[630]]
get 0x002003a9a8 put 0x002003aa98 ib_get 0x00000132 ib_put 0x00000183 state
0x80004610 (err: INVALID_CMD) push 0x00406040
[ 2996.725428] nouveau E[   PFIFO][0000:01:00.0] DMA_PUSHER - ch 2 [Xorg[630]]
get 0x002003e150 put 0x002003e27c ib_get 0x00000080 ib_put 0x000000d7 state
0x80000024 (err: INVALID_CMD) push 0x00406040
[ 3042.646374] nouveau E[Xorg[630]] failed to idle channel 0xcccc0000
[Xorg[630]]
[ 3057.646368] nouveau E[Xorg[630]] failed to idle channel 0xcccc0000
[Xorg[630]]

then the session "reboot" to GDM (gnome login manager)


I attach the entire dmesg log