On Thu, May 9, 2013 at 4:44 PM, Jerome Glisse <j.glisse@xxxxxxxxx> wrote: > On Thu, May 9, 2013 at 3:46 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: >> A fair number of drivers (mostly graphics) add write-combining MTRRs. >> Most ignore errors and most add the MTRR even on PAT systems which don't >> need to use MTRRs. > > This comment is wrong, as i said we need MTRR on PAT system for VRAM. I didn't follow it last time. - If userspace is setting an MTRR directly, then it will work exactly as before -- this patch has no effect on the userspace MTRR APIs. - If userspace uses the drm map interface with DRM_FRAME_BUFFER or DRM_WRITE_COMBINING, there won't be an MTRR but the range will still be WC. - If userspace uses GEM or TTM, then everything should still use WC (TTM has explicit handling for this, which I presume is correct, and i915, the major GEM user, already doesn't set an MTRR). - If userspace does not map the range, then either the kernel driver is buggy or it doesn't matter because there's no map. Is there a case I've missed? --Andy _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
