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Date:      Mon, 18 Jan 1999 01:07:16 +0000 (GMT)
From:      Karl Pielorz <kpielorz@tdx.co.uk>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        lcremean@tidalwave.net, current@FreeBSD.ORG
Subject:   Re: Problems with new IDE's & -current
Message-ID:  <Pine.BSF.4.05.9901180104390.38268-100000@caladan.tdx.co.uk>
In-Reply-To: <199901172356.KAA05189@godzilla.zeta.org.au>

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On Mon, 18 Jan 1999, Bruce Evans wrote:

> New models of IBM IDE drives are fast enough to consume a significant
> fraction (perhaps > 100%) of PIO mode 4 bandwidth (16.6 MB/s).  Don't
> use them without DMA.  Don't use them without UltraDMA (33.3 MB/s) if
> you want full performance.

I presume the last "don't" should have been a 'do', i.e. _do_ use them
with UltraDMA if you want full performance...?

Also, the controller their running off isn't _Any_ DMA capable, at a guess
it's going to be PIO4 tops, in which case (and as EIDA/UltraDMA are mean't
to be 'backwards' compatible) - does this point to a bug/problem with the
wdc driver? (i.e. drive too fast = wdc interrupt timeouts?)

-Kp


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