Re: GGI Project Unhappy On Linux
Olivier Galibert (galibert@pobox.com)
Fri, 27 Mar 1998 22:41:37 +0100
On Fri, Mar 27, 1998 at 12:11:52AM +0000, Alan Cox wrote:
> > > Dear graphics controller, there is a nice pixmap in main memory at
> > > 0xD0A13C30, its 64x64 pixels square and in RGB888 format, please map it
> > > to the 8bit mode colours you are in and dither if neccessary. If you'd be
> > > kind enough to post me an interrupt when you've finished I'd be greatful
> >
> > OK, that sounds nice, but... my 1024x1024 image is in application VM,
> > which is fragmented in physical RAM. Does this humble request include
> > a page translation table? Or can the graphics chip access the CPUs MMU?
> > Or are we stuck with pre-allocating "DMA buffers" and doing an extra
> > copy?
>
> Firstly you can say its lots of smaller blocks, secondly some AGP cards will
> allegedly be able to do scatter gather. At this point please consult a real
> graphics hardware guru not a passing reader of video card manuals and info ;)
AGP includes a full MMU-like address remapping capability. Digital's
PCI chipset for alpha has an equivalent thingy for PCI.
Hey, even PCI bridges start to have nice remapping capabilities.
OG.
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