On Thu, Apr 13, 2000 at 12:15:08AM +1000, Andrew Apted wrote:
> Andreas Beck writes:
>
> > > The X server (XGGI) uses direct access to the buffers, so you never
> > > know when it has changed something or not. The only solution is to
> > > make a smarter X server.
> >
> > Yes basically, though a possible workaround would be to use some kind of
> > checksumming procedure that would try to autodetect the changed regions.
>
> One idea I was pondering was to use the MMU "dirty" bit to track which
> areas of the buffer had been modified -- prolly not possible in Linux
> (IIRC the dirty bit is used by Linux for doing swapping stuff).
I don't know anything about wether this is possible in Linux, but I
know this exact tecnique is used in ShapeShifter (a Mac emulator for
the Amiga). It has to convert the display from packed to planar format
at every screen update. The fastest display routines for it set the
MMU to use small windows (256 bytes) and only update the damaged
regions.
--
Niklas
