kern/140979: Kernel panic (fatal trap 12: page fault when in kernel mode) on FreeBSD 8.0 with ACPI because of "ec" sub-device

[Tarick]

>Number:         140979
>Category:       kern
>Synopsis:       Kernel panic (fatal trap 12: page fault when in kernel mode) on FreeBSD 8.0 with ACPI because of "ec" sub-device
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Nov 28 18:30:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Tarick
>Release:        8.0
>Organization:
home
>Environment:
FreeBSD home 8.0-STABLE FreeBSD 8.0-STABLE #3: Fri Nov 27 11:00:19 EET 2009     root at home:/usr/obj/usr/src/sys/KLH  amd64
Also, using 8.0-RELEASE-amd64-livefs.iso produces the same panic.
>Description:
Booting 8.0-stable and from the 8.0 livefs CD produces kernel panic with trace:
___________________________________________________________________
--skipped--
acpi_lid0: <Control Method Lid Switch> on acpi0
acpi_acad0: <AC Adapter> on acpi0

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault viftual address = 0x40
fault code            = supervisor read data, page not present
instruction pointer   = 0x20:0xffffffff001ccfa0
stack pointer         = 0x20:0xffffffff00c6f070
frame pointer         = 0x20:0xffffffff00c6f0a0
code segment          = base 0x0, limit 0xffffff, type 0x1b
                      = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags      = interrupt enabled, resume, IOPL=0
current process       = 0 (swapper)
trap number           = 12
panic:  page fault
cpuid = 0
Uptime: 1s
Automatic reboot <skipped>
______________________________________________________________________

The system is Dell Inspiron 1501, latest BIOS 2.6.3. FreeBSD was upgraded from working previously 7.2 with ACPI.

Disabling ACPI during the boot helps, and later I was able to isolate the problem to "ec" sub-device (debug.acpi.disabled="ec")
>How-To-Repeat:
Boot with FreeBSD 8.0 CD with ACPI enabled on Dell Inspiron 1501. Don't have another one to verify though.
>Fix:
Put into /boot/loader.conf:
debug.acpi.disabled="ec"

>Release-Note:
>Audit-Trail:
>Unformatted: