Messages in this thread |  | | Date | Sun, 29 Apr 2001 16:05:39 -0500 | From | Steffen Persvold <> | Subject | Re: ServerWorks LE and MTRR |
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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 Fax : (+47) 2262 8951 N-0621 Oslo, Norway
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