Re: cacheflush system call-MIPS

[David Daney <ddaney@caviumnetworks.com>]

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.
David Daney



> kind regards
>
>
>
> On Fri, 13 Feb 2009, Ralf Baechle wrote:
>
> > Date: Fri, 13 Feb 2009 23:56:03 +0000
> > From: Ralf Baechle <ralf@linux-mips.org>
> > To: peter fuerst <post@pfrst.de>
> > Cc: naresh kamboju <naresh.kernel@gmail.com>, linux-mips@linux-mips.org
> > Subject: Re: cacheflush system call-MIPS
> >
> > On Sat, Feb 14, 2009 at 12:50:46AM +0100, peter fuerst wrote:
> >
> > > there is one more good reason to ... : the Impact Xserver needs to do
> > > a cacheflush(a,w,DCACHE) as part of the refresh-sequence.
> > > And hence requires a sys_cacheflush, let's say, more conforming to the
> > > man-page (or some disgusting new ioctl in the Impact kernel-driver to
> > > do an equivalent operation ;-)
> > Why does it need that flush?
> >
> >   Ralf