From owner-freebsd-current@FreeBSD.ORG  Tue Oct  7 18:11:31 2003
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Date: Tue, 7 Oct 2003 18:11:30 -0700 (PDT)
From: Doug White <dwhite@gumbysoft.com>
To: YONETANI Tomokazu <t-yonetani@ergobrains.co.jp>
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References: <20031007040349.GA10406@ergobrains.co.jp>
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cc: freebsd-current@freebsd.org
Subject: Re: savecore: first and last dump headers disagree on /dev/ad0b
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On Tue, 7 Oct 2003, YONETANI Tomokazu wrote:

> The hardware is IBM NetFinity 6000R, and it has ServerWorks ROSB4 UDMA33
> controller, to which the IDE disk is attached. The size of the IDE hard
> disk is 4Gbytes, and the size of the kernel dump and physical memory both
> fits in that size.

The ROSB4 is known to have data-corruption problems with running in UDMA
mode.  The dump is probably tripping over this, which is why Tor's patch
works since it demotes the device back to PIO.

You could optionally set hw.ata.ata_dma=0 in loader.conf to disable UDMA
rather than apply the patch.

-- 
Doug White                    |  FreeBSD: The Power to Serve
dwhite@gumbysoft.com          |  www.FreeBSD.org