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Date:      Tue,  1 Sep 1998 12:31:48 -0400 (EDT)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        mjacob@feral.com
Cc:        freebsd-alpha@FreeBSD.ORG
Subject:   Re: Alpha Install - oops!
Message-ID:  <13804.8316.576176.582569@grasshopper.cs.duke.edu>
In-Reply-To: <Pine.LNX.4.02.9809010915570.17849-100000@feral-gw>
References:  <13804.2770.473870.7600@grasshopper.cs.duke.edu> <Pine.LNX.4.02.9809010915570.17849-100000@feral-gw>

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Matthew Jacob writes:
 > 
 > 
 > I'd watch this for crossing page boundaries on reads if you're using any
 > S/G map stuff. In fact, I'd have an extra mapping at the end of
 > the S/G list that just remaps the first page so that any prefetch
 > on a read won't get a fault but will just pick up known good data.

Gee, I'd hope a GL would be smart enough not to prefectch past the end
of a S/G segment; I do know that the page-boundry DMA restriction is gone on GL's. 

However, I use the direct-map segment in my Myrinet drivers (on DU &
on *BSD), so I can't verify that it doesn't happen.

Drew


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