*BSD News Article 13191


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Newsgroups: comp.os.386bsd.bugs
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From: scott@pita.cns.ucla.edu (Scott Burris)
Subject: Re: Julian's 1542B driver and > 16MB
Message-ID: <scott.732832105@pita>
Nntp-Posting-Host: pita.cns.ucla.edu
References: <1993Mar22.091308.18241@qualcomm.com>
Date: 22 Mar 93 12:43:01 PST
Lines: 31

karn@servo.qualcomm.com (Phil Karn) writes:

>I've been running Julian's Adaptec 1542B SCSI driver on my 16 MB 486
>system for several weeks without any problems. Yesterday, during a CPU
>upgrade (from 486-50 to 486DX2-66) I added 4 more meg of memory to see
>if it would help X to run a little faster.

Deja Vu, I also added 4 meg of memory a few months back to get 20Meg.

>Big mistake. The system seemed to run OK until I ran fsck on my main
>filesystem (a SCSI disk). It completed, but then the system abruptly
>rebooted. Then it got worse -- the fsck found increasing damage, and
>eventually /386bsd got wiped out.

>I suspected a problem with DMA above 16MB, so I removed the extra 4 meg,
>booted from a backup disk and rebuilt my kernel. It's been running solid
>ever since.

The driver makes no provisions for memory above 16 Meg.  I too was lucky
in that I realized what was going on before I trashed everything and was
able to restore all I had lost.

At some point I was going to going to write the bounce buffer code to
fix this in my copious spare time :-), but I think I'll just move
386bsd to an EISA system with a 1742A instead.  I haven't heard of
anyone else working on the fix -- if they are, I'd be glad to here about it.
-- 
----------
Scott Burris
UCLA Campus Network Services
cnetslb@oac.ucla.edu (310) 206-4860 - OR - scott@pita.cns.ucla.edu