Switching to text console and back hangs X server
Submitted by Pawel Salek
Assigned to Xorg Project Team
It appears that this is probably a bug in the SiS driver not saving/restoring properly. Switching the virtual console to text mode and back leaves the Xorg process unresponsive and the screen white. This problem has appearead in Fedora rawhide in the last month, I believe. The box as such is alive and one can connect via ssh to it. See also https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=180465 for the original report.
After the hang, the Xorg process gets stuck. It utilizes 100% CPU. When I connect gdb to Xorg, I get following stack trace:
(gdb) where #0 0x00000036286bd900 in __write_nocancel () from /lib64/libc.so.6 #1 0x0000003628667793 in _IO_new_file_write () from /lib64/libc.so.6 #2 0x0000003628668bef in _IO_new_file_xsputn () from /lib64/libc.so.6 #3 0x000000362865e89b in fwrite () from /lib64/libc.so.6 #4 0x00000000005666a2 in LogVWrite () #5 0x000000000056717d in LogVMessageVerb () #6 0x0000000000481f2c in xf86VDrvMsgVerb () #7 0x00002b59ab2893c2 in sisRestoreExtRegisterLock () from /usr/lib64/xorg/modules/drivers/sis_drv.so #8 0x00002b59ab28b2f5 in sisSaveUnlockExtRegisterLock () from /usr/lib64/xorg/modules/drivers/sis_drv.so #9 0x00002b59ab28f4d9 in SiS_SetSISTVedgeenhance () from /usr/lib64/xorg/modules/drivers/sis_drv.so #10 0x00002b59ab29b3cd in SISAdjustFrame () from /usr/lib64/xorg/modules/drivers/sis_drv.so #11 0x00002b59ab29b850 in SISAdjustFrame () from /usr/lib64/xorg/modules/drivers/sis_drv.so #12 0x00002b59ab5fa69b in xf86ForceHWCursor () from /usr/lib64/xorg/modules/libramdac.so #13 0x000000000047f7d1 in xf86InitFBManagerArea () #14 0x000000000048c152 in xf86XVScreenInit () #15 0x0000000000479714 in xf86Wakeup () #16 0x000000000044e2a5 in WakeupHandler () #17 0x0000000000559cb4 in WaitForSomething () #18 0x000000000044a33a in Dispatch () #19 0x0000000000432c95 in main ()