Kernel panic with ACPI enabled

[John Baldwin]

On Wednesday 08 February 2006 02:59, Nate Lawson wrote:
> John Baldwin wrote:
> > On Tuesday 07 February 2006 15:13, Donald J. O'Neill wrote:
> >>Other things can affect what he's trying to do and cause him to think he
> >>has an ACPI problem. I had a bad USB mouse that was causing problems on
> >>one of my computers, in fact anything USB on that computer caused a
> >>problem with ACPI (it had to be disabled to allow the computer to
> >>boot-up) if that mouse was plugged in, until I found the mouse was bad
> >>and switched it with one that was ok. On another computer, I could only
> >>boot-up if I either disabled ACPI or had the USB mouse unplugged. After
> >>it was up, the mouse could be plugged back in and it would work, ACPI
> >>would work, but I would be left wondering about the situation. I
> >>finally decided to just use a PS-2 mouse and wait a while. That works
> >>fine, although I hate ball mice.
> >
> > Actually, in his case I'm fairly sure MAXMEM is the problem.  Several
> > people have had problems trying to use the tunable equivalent
> > (hw.physmem=3g and the like) because if the new maxmem value is greater
> > than the highest memory address we found, we just extend the last segment
> > of physical memory. However, in the case of modern machines with SMAPs,
> > this extension can result in including memory that was specifically
> > marked as unavailable (because it was in use by the BIOS to store the
> > ACPI tables) suddenly being used by the kernel.  As part of this process,
> > the kernel does test writes to each page, so it would corrupt the ACPI
> > tables and eventually lead to issues such as this.
>
> Can we at least put a printf() in the boot sequence that says "warning:
> maxmem set and acpi enabled, this may cause problems"?  This keeps
> coming up.

We don't know we are using ACPI when we do the maxmem and hw.physmem stuff.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org