Xorg server may crash system

[Sverre Froyen <sverre%viewmark.com@localhost>]

Hi,

In the process of upgraging my laptop, I noticed the following quirk with the 
NetBSD DRM code:

With a config that contains, e.g.,

radeondrm* at vga?
options DRM_DEBUG

and no i915drm line, and using the xf86-video-intel driver in xorg, the lines

dev = DRIVER_SOFTC(minor(kdev));
DRM_DEBUG( "open_count = %d\n", dev->open_count );

in src/sys/dev/drm/drm_drv.c (drm_open) causes a uvm_fault as dev is NULL.

Corner case, obviously, but it bit me.

Regards,
Sverre