port-i386/49562: i915drmkms panic during boot

[jarle%uninett.no@localhost]

>Number:         49562
>Category:       port-i386
>Synopsis:       i915drmkms panic during boot
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-i386-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jan 13 08:00:00 +0000 2015
>Originator:     Jarle Greipsland
>Release:        NetBSD 7.99.4
>Organization:
	
>Environment:
	
	
System: NetBSD singsaker.uninett.no 7.99.4 NetBSD 7.99.4 (GENERIC) #4: Mon Jan 12 23:54:58 CET 2015  jarle%singsaker.uninett.no@localhost:/usr/obj/sys/arch/i386/compile/GENERIC i386
Architecture: i386
Machine: i386
>Description:
I tried to boot a -current GENERIC kernel built yesterday on my Lenovo
T400s.  It paniced during autoconfiguration.  Console messages (ten finger
copy):
[ ... ]
pchb0 at pci0 dev 0 function 0: vendor 8086 product 2a40 (rev. 0x07)
agp0 at pchb0: GX4-family chipset
agp0: detected 32252k stolen memory
agp0: aperture at 0xd0000000, size 0x10000000
i915drmkms0 at pci0 dev 2 function 0: vendor 80086 product 2a42 (rev. 0x07)
drm: Memory usable by graphics device = 512M
drm: Supports vblank timestamp caching Rev 2 (21.10.2013)
drm: Driver supports precise vblank timestamp query.
i915drmkms0: interrupting at ioapic0 pin 16 (i915)
DRM error in init_ring_common: render ring initialization failed ctl 0001f001 head c454d07c tail 00000000 start 00003000
warning: /usr/src/sys/external/bsd/drm2/dist/drm/i915/inten_pm.c:5734: !power_domains->domain_use_count[domain]
panic: cpu_switchto: switching above IPL_SCHED (8)
fatal breakpoint in supervisor mode
trap type 1 code 0 epi c02a4094 cs 8 eflags 246 cr2 0 ilevel 8 esp c125194c
curlwp 0xc105f2a0 pid 0 lid 1 lowest kstack 0xc124f2c0

> bt
breakpoint
vpanic
snprintf
cpu_switchto
sleepq_block
cv_wait
linux_flush_workqueue
flush_scheduled_work
intel_modeset_cleanup
i915_driver_load
drm_dev_register
drm_pci_attach
i915drmkms_attach
config_attach_loc
pci_probe_device
pci_enumerate_bus
pcirescan
pciattach
config_attach_loc
config_found_ia
mp_pci_scan
mainbus_rescan
mainbus_attach
config_attach_loc
config_rootfound
cpu_configure
main

See also the thread starting with
http://mail-index.netbsd.org/current-users/2014/11/18/msg026163.html
for some similar problems.

A curious fact is that I can boot and happily use the -current kernel
provided I first boot an older kernel (in my case a kernel of 6.99.44
vintage) to single user, reboot, and then boot the -current kernel without
an intermediate powerdown.  Maybe something is not correctly initialized
with the -current kernel?

>How-To-Repeat:
Boot a -current kernel on a similar system?
	
>Fix:
	

>Unformatted: