> On Jan 16, 2008 3:14 PM, erik quanstrom <[EMAIL PROTECTED]> wrote: > > > is there a problem with the generality of this patch? > > Note that the patch is saved, and I'm guessing there is a reason: it's > arguably gross to expose the MTRRs to the world. I was thinking about > this. It seems to me that MTRRs could really be managed in mmu.c (but > it's a headache). You would need to know when a device mapped physical > memory that it ought to be cached, and set the MTRRs up properly.
i would think that either aux/vga or the kernel driver for the card in question could set this up. > > > > > it would also be nice if the kernel kept it's own copy > > of the frame buffer. nvidia^wmodern graphics cards are just not > > designed to be read from. > > I know that is true on AGP, but had understood it to be less true on > PCIe. Is it really so bad on PCIe now? as i understand it, the problem is not the bandwidth of the link. the problem is that firmware running on the graphics card'is not set up to handle read requests quickly. i think they assume that you're not going to do that. as one data point, my pcie-based nvidia card raises windows much more slowly than the older agp one that i have. and the pcie card has every advantage. the agp card runs in a intel celery system. - erik
