On Tue, Feb 17, 2009 at 09:06:32AM -0800, David Daney wrote: > peter fuerst wrote: >>> Why does it need that flush? >> To prepare the update-area (in the Shadow-FB) for DMA to RE. > > And on systems where the root frame buffer is directly manipulated by the > CPU, the video system is continually using DMA to refresh the display. A > cache flush can be required to eliminate transient visual glitches. In this case using uncached fb access is the only way to avoid glitches - you cannot control cache line evictions. And it's usually faster to use uncached mappings for effectively write-only regions. -- Eugene
