[Linux-fbdev-devel] Re: FB model basic issues (WAS: radeon, apertures & memory mapping)

[Ville Syrjälä]

On Thu, Mar 17, 2005 at 10:08:15AM +0100, Geert Uytterhoeven wrote:
> On Thu, 17 Mar 2005, Ville [iso-8859-1] Syrj??wrote:
> > On Thu, Mar 17, 2005 at 12:12:58PM +1100, Benjamin Herrenschmidt wrote:
> > > > I understand you can't have userspace program the accelerator while 
> > > > someone else is doing the same thing. Oh and I now understand that the 
> > > > same really applies to direct framebuffer access due to the swapper.  
> > > 
> > > And you can't have someone program the accelerator while somebody does
> > > direct access neither. It's basically all exclusive.
> > 
> > I haven't seen that happen on any hardware I own. Matrox specs explicitly 
> > mention that there is no need to synchronize accelerator and direct 
> > framebuffer access.
> 
> Really?

Really.

> I was always given Matrox as an example of a card that would lock up if
> you access the frame buffer while the accelerator is busy...

Apparently they didn't know what they were talking about.

-- 
Ville Syrjälä
syrjala at sci.fi
http://www.sci.fi/~syrjala/