Re: ServerWorks LE and MTRR

nick
2001-04-29T22:15:08Z

Are you sure that is not due to board design differences?
Nick

On Sun, 29 Apr 2001, Steffen Persvold wrote:

> Gérard Roudier wrote:
> >
> > On Sun, 29 Apr 2001, Steffen Persvold wrote:
> >
> > > Hi all,
> > >
> > > I just compiled 2.4.4 and are running it on a Serverworks LE motherboard.
> > > Whenever I try to add a write-combining region, it gets rejected. I took a peek
> > > in the arch/i386/kernel/mtrr.c and found that this is just as expected with
> > > v1.40 of the code. It is great that the mtrr code checks and prevents the user
> > > from doing something that could eventually lead to data corruption. Using
> > > write-combining on PCI acesses can lead to this on certain LE revisions but
> > > _not_ all (only rev < 5). Therefore please consider my small patch to allow the
> > > good ones to be able to use write-combining. I have several rev 06 and they are
> > > working fine with this patch.
> >
> > You wrote that 'only rev < 5' can lead to data corruption, but your patch
> > seems to disallow use of write combining for rev 5 too.
> >
> > Could you clarify?
>
> Oops just a typo, it should be <= 5. The patch is correct.
>
> >
> > Gérard.
> >
> > PS:
> > >From what hat did you get this information ? as it seems that ServerWorks
> > require NDA for letting know technical information on their chipsets.
> >
>
> I've learned it the hard way, I have two types : Compaq DL360 (rev 5) and a
> Tyan S2510 (rev 6). On the compaq machine I constantly get data corruption on
> the last double word (4 bytes) in a 64 byte PCI burst when I use write
> combining on the CPU. On the Tyan however the transfer is always ok.
>
> --
> Steffen Persvold Systems Engineer
> Email : mailto:sp@scali.com Scali AS (http://www.scali.com)
> Norway : Tel : (+47) 2262 8950 Olaf Helsets vei 6
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>
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