kern/49424: DRMKMS failure on Lenovo T410s with amd64/7.0_BETA

[he%NetBSD.org@localhost]

>Number:         49424
>Category:       kern
>Synopsis:       DRMKMS failure on Lenovo T410s with amd64/7.0_BETA
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Nov 27 15:00:00 +0000 2014
>Originator:     Havard Eidnes
>Release:        NetBSD 7.0_BETA
>Organization:
	None
>Environment:
System: NetBSD xxx 7.0_BETA NetBSD 7.0_BETA (DRMKMS) #1: ...
Architecture: amd64
Machine: amd64
>Description:
	The DRMKMS kernel, built from netbsd-7 sources checked out
	today panics during autoconfig on this type of host.  The
	kernel messages near the failure point is:

pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
pchb0 at pci0 dev 0 function 0: Intel Iron Lake Host Bridge (rev. 0x02)
agp0 at pchb0: G4X-family chipset
agp0: detected 32252k stolen memory
agp0: aperture at 0xd0000000, size 0x10000000
i915drmkms0 at pci0 dev 2 function 0: Intel Iron Lake Integrated Graphics Device (rev. 0x02)
drm: Memory usable by graphics device = 512M
panic: lockdebug_lookup: uninitialized lock (lock=0xffffffff81158000, from=ffffffff8053c715)
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip ffffffff8028dfed cs 8 rflags 246 cr2 0 ilevel 8 rsp ffffffff81383708
curlwp 0xffffffff811132c0 pid 0.1 lowest kstack 0xffffffff813802c0

	I have a backtrace as a picture on my cellphone; will decode
	that later (sunday?).

	A GENERIC kernel probes the graphics as

pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
pchb0 at pci0 dev 0 function 0: vendor 0x8086 product 0x0044 (rev. 0x02)
agp0 at pchb0: G4X-family chipset
agp0: detected 32252k stolen memory
agp0: aperture at 0xd0000000, size 0x10000000
vga0 at pci0 dev 2 function 0: vendor 0x8086 product 0x0046 (rev. 0x02)
wsdisplay0 at vga0 kbdmux 1: console (80x25, vt100 emulation), using wskbd0
wsmux1: connecting to wsdisplay0
drm at vga0 not configured
vendor 0x8086 product 0x3b64 (miscellaneous communications, revision 0x06) at pci0 dev 22 function 0 not configured

	(The vesa X11 driver doesn't appear to want to drive the
	display at its native 1440x900, instead it does 1280x800, with
	predictable suboptimal result.)

>How-To-Repeat:
	Try to boot the DRMKMS kernel, on a Lenovo T410s, watch it
	panic during probing with the above message.

>Fix:
	Sorry, I've not investigated further.