Date: Fri, 3 Jan 2003 06:36:29 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Bruce Campbell <bruce@engmail.uwaterloo.ca> Cc: freebsd-hardware@FreeBSD.ORG, <freebsd-questions@FreeBSD.ORG> Subject: Re: Followup to "fallback to PIO mode" on dual processor AMD systems Message-ID: <20030103062516.F755-100000@gamplex.bde.org> In-Reply-To: <1041526384.3e146e708b8e4@www.nexusmail.uwaterloo.ca>
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On Thu, 2 Jan 2003, Bruce Campbell wrote:
> At present, I don't suspect bad media because the error message is
> "WRITE command timeout tag=0 serv=0" which doesn't suggest a specific
> sector/track etc, and running with UDMA33 instead of UDMA100 makes the problem
> appear to vanish.
The fallback is clearly wrong because it turns isolated media errors
into pessimized i/o for the whole disk at best, system hangs during
resets next best, and system crashes at worst. I keep a disk with bad
media on line for testing some of this, and zap the fallback using the
following patch (hope this is complete; it was edited from a larger
patch).
%%%
Index: ata-disk.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/ata/ata-disk.c,v
retrieving revision 1.139
diff -u -2 -r1.139 ata-disk.c
--- ata-disk.c 17 Dec 2002 16:26:22 -0000 1.139
+++ ata-disk.c 18 Dec 2002 01:03:37 -0000
@@ -597,5 +606,5 @@
else {
ata_dmainit(adp->device, ata_pmode(adp->device->param), -1, -1);
- printf(" falling back to PIO mode\n");
+ printf(" NOT falling back to PIO mode\n");
}
TAILQ_INSERT_HEAD(&adp->device->channel->ata_queue, request, chain);
@@ -603,4 +612,5 @@
}
+#if 0
/* if using DMA, try once again in PIO mode */
if (request->flags & ADR_F_DMA_USED) {
@@ -613,4 +623,5 @@
return ATA_OP_FINISHED;
}
+#endif
request->flags |= ADR_F_ERROR;
%%%
Bruce
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