On Mon, 26 Nov 2012 21:52:54 -0800, Ben Widawsky <ben at bwidawsk.net> wrote: > This bug was introduced by me: > commit e76e9aebcdbfebae8f4cd147e3c0f800d36e97f3 > Author: Ben Widawsky <ben at bwidawsk.net> > Date: Sun Nov 4 09:21:27 2012 -0800 > > drm/i915: Stop using AGP layer for GEN6+ > > The existing code uses memset_io which follows memset semantics in only > guaranteeing a write of individual bytes. Since a PTE entry is 4 bytes, > this can only be correct if the scratch page address is 0. Gah. Wasn't there an iowrite32_rep? > This caused unsightly errors when we clear the range at load time, > though I'm not really sure what the heck is referencing that memory > anyway. I caught this is because I believe we have some other bug where > the display is doing reads of memory we feel should be cleared (or we > are relying on scratch pages to be a specific value). That's just because we are no longer disabling outputs before updating the GTT and hence continue to scanout from the BIOS fb during module load. It's a regression that we'll be able to finally fix properly with fastboot - though that will not be without its downsides either. -Chris -- Chris Wilson, Intel Open Source Technology Centre
