Re: cacheflush system call-MIPS

[Eugene Surovegin <ebs@ebshome.net>]

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