On 23/11/12(Fri) 21:35, Mark Kettenis wrote: > > Date: Fri, 23 Nov 2012 12:23:19 +0100 > > From: Martin Pieuchot <[email protected]> > > > > Ok, a bit of explanation first. > > > > On macppc because the AGP chips do not translate pages, the kernel and > > the applications have access to the AGP memory regions through standard > > mappings. Because these regions are mean to share commands and data and > > the AGP bridges are not cache-coherent, they are mapped NOCACHE by the > > appleagp driver. > > > > However in the case of the dri/drm infrastructure these memory regions > > are first allocated and mapped by the agp driver then mmap'ed by the > > userland graphic driver. > > Martin, I probably should have asked this earlier, but how is this > memory mapped by the userland graphics driver? Is that done by > opening /dev/agp and then calling mmap(2) on the filedescriptor? If > so, perhaps a better approach would be to have the agp mmap function > return a PMAP_NC bit in the lower bits of the physical address. This > is what sparc and sparc64 do.
Great! That is exactly what I was looking for. I'm cooking the drm diff, please forget this one. Martin
