From owner-freebsd-fs  Thu Sep 21 11: 3:53 2000
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From: Soren Schmidt <sos@freebsd.dk>
Message-Id: <200009211807.UAA37597@freebsd.dk>
Subject: Re: disable write caching with softupdates?
In-Reply-To: <200009211702.KAA13662@bubba.whistle.com> from Archie Cobbs at "Sep 21, 2000 10:02:16 am"
To: archie@whistle.com (Archie Cobbs)
Date: Thu, 21 Sep 2000 20:07:55 +0200 (CEST)
Cc: mbendiks@eunet.no (Marius Bendiksen), sos@freebsd.org,
	fs@freebsd.org, terry@lambert.org
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It seems Archie Cobbs wrote:
> Marius Bendiksen writes:
> > > > The ATA drives Whistle is using, which is what I'm assuming
> > > > Archie is on about, do _not_ support this facility.  As far
> > > > as I can tell, there wre some SCSI drives manufactured by
> > > > IBM at one time which could do this, and some lab drives at
> > > > Quantum (also SCSI).
> > > Hmm, well, lets disable this then, there is no need to complicate
> > > things :)
> > 
> > Please make this conditional, as people with non-crippled hardware might
> > want to employ the write cache. A sysctl or build option would be best.
> 
> Yep, that was what I was originally suggesting.
> 
> Soren do you want me to try to come up with a patch? 
> I don't claim to understand IDE technology.. can you
> just send the disable command at any time or is it
> more complicated than that?

This will do it, or rather leave it as the disk default which
should be disabled...

cvs diff: Diffing .
Index: ata-disk.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/ata/ata-disk.c,v
retrieving revision 1.77
diff -u -r1.77 ata-disk.c
--- ata-disk.c	2000/09/20 07:00:24	1.77
+++ ata-disk.c	2000/09/21 18:00:15
@@ -131,11 +131,11 @@
     if (ata_command(adp->controller, adp->unit, ATA_C_SETFEATURES,
 		    0, 0, 0, 0, ATA_C_F_ENAB_RCACHE, ATA_WAIT_INTR))
 	printf("ad%d: enabling readahead cache failed\n", adp->lun);
-
+#if NOTYET
     if (ata_command(adp->controller, adp->unit, ATA_C_SETFEATURES,
 		    0, 0, 0, 0, ATA_C_F_ENAB_WCACHE, ATA_WAIT_INTR))
 	printf("ad%d: enabling write cache failed\n", adp->lun);
-
+#endif
     /* use DMA if drive & controller supports it */
     ata_dmainit(adp->controller, adp->unit,
     		ata_pmode(AD_PARAM), ata_wmode(AD_PARAM), ata_umode(AD_PARAM));

-Søren


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