Date: Fri, 15 May 1998 15:19:48 -0500 (EST) From: "John S. Dyson" <dyson@FreeBSD.ORG> To: phk@critter.freebsd.dk (Poul-Henning Kamp) Cc: dyson@FreeBSD.ORG, sos@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: People having problems with X windows? Message-ID: <199805152019.PAA02838@dyson.iquest.net> In-Reply-To: <2028.895222610@critter.freebsd.dk> from Poul-Henning Kamp at "May 15, 98 10:56:50 am"
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Poul-Henning Kamp said: > In message <199805150738.CAA03075@dyson.iquest.net>, "John S. Dyson" writes: > > >I just removed my WC "improvements", by adding the return to the > >subroutine in the pmap code. See if it is more friendly. The > >symptoms appear to be those associated with improper setting of > >WC mode for a display adaptor. I had to add a heuristic to make > >it work correctly on one of my cards, but I guess it was bad. > > > >The code is still in there, but I guess there is the need for more > >research into the issue. > > I would expect WC to break any and all accelerated adapters that > communicate with the graphics engine through the ram window... > > What is needed is to XFree86 to be able to madvise the true frame > buffer as "Write-combine" and leave the rest of the ram window > unaffected. > There are two forms of PCI RAM. One type is prefetchable and the other type isn't. The problem is that some adaptors might be specifying that some ram is prefechable when it isn't. My Matrox specifies them correctly, but my S3 Motion 771 doesn't. I added a heuristic so that the S3 could use the WC mode, but could have broken other adaptors. -- John | Never try to teach a pig to sing, dyson@freebsd.org | it just makes you look stupid, jdyson@nc.com | and it irritates the pig. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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