Messages in this thread | | | Date | Sun, 18 May 2003 17:11:05 +0100 | From | Jamie Lokier <> | Subject | Re: [PATCH] Use MTRRs by default for vesafb on x86-64 |
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Andi Kleen wrote: > On Fri, May 16, 2003 at 10:51:36PM +0200, Alan Cox wrote: > > On Iau, 2003-05-15 at 16:16, Dave Jones wrote: > > > There are PCI ET4000's too. Though if we can get the PCI IDs for those, > > > we can work around them with a quirk. I have one *somewhere*, but it'll > > > take me a while to dig it out. > > > > Some older SiS cards have problems too. I have a 6326 that doesn't work > > with sisfb (too old) and vesafb with mtrr fails. > > Can you provide PCI info for them to add a quirk ?
What exactly "doesn't work" with these cards?
I'm thinking that the only way write-combining MTRRs could possibly break a framebuffer is if part of the address range is used as a register bank - otherwise, to the card, it just looks like well written rendering code.
If this is so, then it might be possible to set write-combining MTRRs while the framebuffer is operating, but to temporarily disable those MTRRs while calling into the VESA BIOS code, for these cards.
And if that does work, then it might even be reasonable to temporarily disable the MTRRs while calling the BIOS for all vesafb cards, thus removing the need for a blacklist -- which is a headache for something that needs to be as portable to unknown cards as vesafb.
-- Jamie
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