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From: Peter Dufault <dufault@hda.com>
Message-Id: <199504252119.RAA22589@hda.com>
Subject: Re: panic: pmap_zero_page: CMAP busy
To: dufault@hda.com (Peter Dufault)
Date: Tue, 25 Apr 1995 17:19:51 -0400 (EDT)
Cc: current@freefall.cdrom.com
In-Reply-To: <199504251953.PAA19684@hda.com> from "Peter Dufault" at Apr 25, 95 03:53:37 pm
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Peter Dufault writes:
> 
> I built a kernel from this morning's sup and it dies on a "Dell Dimension
> 486DX250" with the panic:
> 
> > pmap_zero_page: CMAP busy
> 
> It starts up single user fine, but will panic as soon as you type ps.
> "ps" will go in to "pmap_zero_page" 26 times and on the 27'th time will
> find that CMAP2 is already non-zero.
> 
> The Stack backtrace is
> 
> pmap_zero_page
> vm_page_zero_fill
> vm_fault
> trap_pfault
> trap(27, ...)
> 
> I don't have much experience with this system though it boots the GENERIC
> kernel on the last SNAP fine.

I'll file a full bug report later when I determine exactly what is wrong.

The panic is caused by the difference between these two lines in
the config:

>From GENERIC (works):
> config		kernel	root on wd0 swap on wd0 and wd1 and wd2 and vn0 dumps on wd0

>From DESMOND (panics):
> config		kernel	root on wd0 swap on wd0 dumps on wd0

DESMOND also has the references to "wd1" and "wd2" removed.

Changing desmond back to have "wd1", "wd2" and "vn0" swap made it boot OK.

-- 
Peter Dufault               Real Time Machine Control and Simulation
HD Associates, Inc.         Voice: 508 433 6936
dufault@hda.com             Fax:   508 433 5267