Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!munnari.oz.au!metro!natmlab.dap.csiro.au!ditsydh.syd.dit.CSIRO.AU!evans
From: evans@syd.dit.CSIRO.AU (Bruce.Evans)
Newsgroups: comp.os.minix
Subject: Re: fix to diskcheck(1)
Message-ID: <1990Oct3.193416.18370@syd.dit.CSIRO.AU>
Date: 3 Oct 90 19:34:16 GMT
References: <31308@nigel.ee.udel.edu>
Organization: CSIRO Division of Info Tech, Sydney, Australia
Lines: 18

In article <31308@nigel.ee.udel.edu> archer%segin4.segin.fr@relay.prime.com (Vincent Archer) writes:
>Of course, i should have tought of it. Reading from /dev/mem (or rather
>/dev/kmem) would be very nice. /dev/null is out of question, you CAN'T read

It would have to be /dev/bmem = /dev/mem as a block device since /dev/mem
is a character device and reading it would not affect the cache. /dev/kmem
as a block device would probably be too small.

>The real thing is to solve the cache matter once for all. Use the raw device,
>which bypass the cache entirely.

Yes, except raw disk devices are not implemented for Minix-1.5-PC. Thrashing
the cache on purpose makes using the block device extremely slow. I have
just modified the PC AT driver to handle raw devices. This involved replacing
the fixed sector count BLOCK_SIZE/SECTOR_SIZE by the number of sectors asked
for, and changing some checks.
-- 
Bruce Evans		evans@syd.dit.csiro.au