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Date:      Wed, 16 Apr 2003 13:02:25 -0400 (EDT)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        Jarkko Santala <jake@iki.fi>
Cc:        freebsd-alpha@freebsd.org
Subject:   Re: problem with UDMA mode on XP1000
Message-ID:  <16029.36001.229632.79139@grasshopper.cs.duke.edu>
In-Reply-To: <20030416195422.S316@trillian.santala.org>
References:  <Pine.OSF.4.33.0304151146380.1028-100000@poptart.bithose.com> <20030416122206.S316@trillian.santala.org> <16029.20850.720877.563791@grasshopper.cs.duke.edu> <20030416195422.S316@trillian.santala.org>

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Jarkko Santala writes:
 > I suppose no checking explains the performance. ;) But good to know
 > anyway. Any reason why it gets enabled by default if its not safe?

The ata code just enables the highest available mode by default.

I'm no expert, but I don't think PIO is safe either.  I think it just
stresses things so much less than DMA that its assumed to be safe.

Drew



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