*BSD News Article 75896


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From: chrisj@puffin.com (Chris Jewell)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Can't boot 2.1 with 16MB?
Date: 10 Aug 1996 16:45:12 -0700
Organization: The laughter-filled home of Chris and Jan, Hollister, CA, USA
Lines: 28
Message-ID: <4uj6u8$a1g@tufted.puffin.com>
References: <4ubva8$noa@news3.realtime.net>
NNTP-Posting-Host: localhost.puffin.com
Keywords: cmos

Posted and mailed.

In article <4ubva8$noa@news3.realtime.net>,
Tushar Patel <tushar@ecpi.com> wrote:
...
>I had 386 machine with 8MB of ram and running 2.1 FreeBSD on it fine.
>
>I put 16MB of memory and when I try to boot now then I get following
>message.
...
>fatal trap 12 page fault while in address ....
>Fault virtual address 0x701ed7a4
>fault code = Supervisor read, page not present
>           = 0xc
>panic vm_page_free freeing free page...

In the CMOS setup, if you choose not to shadow various addresses in
the upper 384K of the first megabyte of address space (card ROM BIOS
etc), there may be an option to remap the unused shadow RAM to high
addresses, increasing your available memory.  I recently had symptoms
just like yours on a 486 system, and turning off that option cured the
problem.

According to a friend (Hi, Leonard!), with most motherboard chipsets
remapping of unused shadow RAM works only with 8MB or less, which is
consistent with your experience.
-- 
Chris Jewell    chrisj@puffin.com    1341 Ramona Ave    Hollister CA USA 95023