kern/50304: Panic on boot with enabled ACPI

[frederic%fauberteau.org@localhost]

>Number:         50304
>Category:       kern
>Synopsis:       Panic on boot with enabled ACPI
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Oct 05 12:20:00 +0000 2015
>Originator:     Frédéric Fauberteau
>Release:        NetBSD 7.99.21
>Organization:
>Environment:
NetBSD n150p 7.99.21 NetBSD 7.99.21 (GENERIC) #1: Sun Oct  4 18:45:14 CEST 2015  triaxx@hydralisk:/home/triaxx/dev/nbsd/netbsd-current/usr/objdir/sys/arch/amd64/compile/GENERIC amd64
>Description:
The system crashes with the following backtrace :
0xffffffff801196a5 in cpu_reboot ()
#0  0xffffffff801196a5 in cpu_reboot ()
#1  0xffffffff805ee1f6 in db_sync_cmd ()
#2  0xffffffff805ee9b7 in db_command ()
#3  0xffffffff805eecfe in db_command_loop ()
#4  0xffffffff805f238d in db_trap ()
#5  0xffffffff80116130 in kdb_trap ()
#6  0xffffffff8011a82f in trap ()
#7  0xffffffff80100fde in alltraps ()
#8  0xffffffff80114be5 in breakpoint ()
#9  0xffffffff8080fd0b in vpanic ()
#10 0xffffffff8080fdcf in panic ()
#11 0xffffffff8011bfc4 in cnopen ()
#12 0xffffffff80800736 in cdev_open ()
#13 0xffffffff80875595 in spec_open ()
#14 0xffffffff8086aa57 in VOP_OPEN ()
#15 0xffffffff8086400f in vn_open ()
#16 0xffffffff8085b8e3 in do_open ()
#17 0xffffffff8085ba37 in do_sys_openat ()
#18 0xffffffff8085bb03 in sys_open ()
#19 0xffffffff8013cc0c in syscall ()
#20 0xffffffff80100691 in Xsyscall ()

Some informations from dmesg (without ACPI):
NetBSD 7.99.21 (GENERIC) #1: Sun Oct  4 18:45:14 CEST 2015
  triaxx@hydralisk:/home/triaxx/dev/nbsd/netbsd-current/usr/objdir/sys/arch/amd64/compile/GENERIC
total memory = 1013 MB
avail memory = 965 MB
timecounter: Timecounters tick every 10.000 msec
timecounter: Timecounter "i8254" frequency 1193182 Hz quality 100 
SAMSUNG ELECTRONICS CO., LTD. N150P                       (Not Applicable)
mainbus0 (root)
mainbus0: Intel MP Specification (Version 1.4) (PNVTGPT  PNVTGPT     )   
cpu0 at mainbus0 apid 0
cpu0: Intel(R) Atom(TM) CPU N455   @ 1.66GHz, id 0x106ca
mpbios: bus 0 is type PCI   
mpbios: bus 5 is type PCI   
mpbios: bus 9 is type PCI   
mpbios: bus 10 is type ISA   
ioapic0 at mainbus0 apid 2: pa 0xfec00000, version 0x20, 24 pins
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 8086 product a010 (rev. 0x00)
agp0 at pchb0: i915-family chipset
agp0: detected 7932k stolen memory
agp0: BAR size 100000 mismatches detected GTT size 40000; trusting BAR 
agp0: aperture at 0xd0000000, size 0x10000000
i915drmkms0 at pci0 dev 2 function 0: vendor 8086 product a011 (rev. 0x00)
drm: Memory usable by graphics device = 1024M
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: initialized overlay support
intelfb0 at i915drmkms0
i915drmkms0: info: registered panic notifier
intelfb0: framebuffer at 0xffff800012e00000, size 1024x600, depth 32, stride 4096
wsdisplay0 at intelfb0 kbdmux 1: console (default, vt100 emulation)
wsmux1: connecting to wsdisplay0

intelfb seems to have problem with ACPI but it worked on NetBSD 7.0_RC3.
>How-To-Repeat:
Boot with ACPI
>Fix: