"GPU device drivers are increasingly requiring more
sophisticated support for mapping objects into both userland and
the kernel. For example, memory used for textures often needs to be
mapped Write-Combining rather than Write-Back. I have recently
created three patches to provide several extensions.
"The first patch allows device drivers to use a different VM
object to back specific mmap() calls instead of always using the
device pager. The second patch introduces a new VM object type that
can map an arbitrary set of physical address ranges. This can be
used to let userland mmap PCI BARs, etc. The third patch allows
memory mappings to use different caching modes (e.g.
Write-Combining or Uncacheable).
"Together I believe these patches provide the remaining pieces
needed for an Nvidia amd64 driver. They will also be useful for
future Xorg DRM support as well. The current set of patches can be
safely merged back to 7.x as well."
