kern/46714: Multiple X11 restarts cause kernel panic with i915 + drm

[swiftgriggs%gmail.com@localhost]

>Number:         46714
>Category:       kern
>Synopsis:       Multiple X11 restarts cause kernel panic with i915 + drm
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 17 15:55:00 +0000 2012
>Originator:     Swift Griggs
>Release:        6.0_BETA2
>Organization:
>Environment:
NetBSD daemon.corp.trizetto.com 6.0_BETA2 NetBSD 6.0_BETA2 (GENERIC) i386
>Description:
After getting in and out of X11 several times (ie.. multiple invocations of 
"startx" or "xinit" running). The kernel will panic and the machine dumps core 
and reboots.
>How-To-Repeat:

1. Start X11 on a core2 box with integrated i915 graphics
2. Use ctrl-alt-bksp or ctrl-alt-F1 (followed by a ctrl-c to abort X11) to kill 
xinit.
3. Wait until Xorg is dead
4. Re-run "startx" 
5. Rinse-repeat, until the kernel panics and the box crashes.
>Fix:

Workaround is to never restart X11 on i915 Xorg. Just start it once when the 
machine boots and never cycle Xorg/xinit.