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Date:      Mon, 07 Dec 1998 21:08:45 +0000
From:      Karl Pielorz <kpielorz@tdx.co.uk>
To:        "Kenneth D. Merry" <ken@plutotech.com>
Cc:        "Ron G. Minnich" <rminnich@Sarnoff.COM>, hackers@FreeBSD.ORG
Subject:   Re: write combining memory on pci
Message-ID:  <366C43DD.A7DA16F4@tdx.co.uk>
References:  <199812072105.OAA07499@panzer.plutotech.com>

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"Kenneth D. Merry" wrote:
> 
> Ron G. Minnich wrote...
> > any good ideas on how to turn this on in 3.0 for a given memory address
> > range?
> 
> Isn't there usually a BIOS option to do that?  I think it's called USWC or
> something like that.  (Uniform Speculative Write Combining?)  I don't think
> it generally covers a specific address range, though.

Both my P-Pro systems have this option, and AFAIK it worked as above (i.e.
'all on' or 'all off')... Win NT survives with it on, until I try to use the
sound card, and FreeBSD, Linux & Win'95 all die within seconds with it on...

Which is a bit of a pitty, as I also seem to remember reading it gives a huge
performance win on writes ;-) - Maybe there is such a thing as 'too fast'...
<G>

-Kp

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