On Fri, 2005-09-23 at 13:28 +0100, Dave Airlie wrote: > > > I don't think we can really just nuke support for them, maybe we should > > > fix the support if we can... the problem I have is removing them will > > > signiciantly slow down a lot of working systems.. if the X server doesn't > > > do the correct thing.. > > > > Problem here Dave is that there are probably a lot of systems that use > > the *fb drivers are already slower. In an *fb model in that the user > > hasn't explicitly turned off the mtrr then there's only a small range > > that will actually get configured for video memory. The DRM will already > > fail to add the correct range as the kernel will refuse to overwrite an > > existing range. You may find things speed up in many cases if we remove > > it from the DRM. > > > Looking at X it sets up the framebuffer mtrr for most cards, but nothing > for AGP, mtrr for AGP is as far as I know a big win as we can't cache the > aperture so write combining is needed... maybe we can stop the DRM from > allocating MTRRs for framebuffers in the DRM but leave the code in for the > AGP space... then the i915 can just turn it off in the drm and let X do > it...
Right, that's what I mention in my previous email. But remember that AGP space in Intel hardware is where the framebuffer comes from so X is already doing this for us. So there's no point in the i915 drm doing it for AGP & framebuffer memory as it's the same thing. I'll just remove DRIVER_USE_MTRR from the i915 setup for now. > We can add an option for DRM to turn on mtrr for framebuffer.. or maybe we > can check for an pre-existing and if there is one we can just do nothing, > or add one if not .. or a drm driver option to enable/disable it.. My other point here is that some hardware requires MTRR's to be aligned and the DRM doesn't know how to do that it just ships off the current region to mtrr and doesn't look back. So it needs more intimate knowledge if it's going to continue to do it - regardless of driver. Alan. ------------------------------------------------------- SF.Net email is sponsored by: Tame your development challenges with Apache's Geronimo App Server. Download it for free - -and be entered to win a 42" plasma tv or your very own Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
