Re: Thread-private mappings and graphics (was Re: Per-Processor Data

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 20 Dec 1999 02:56:04 +0000 (GMT)

> processes memory space. For older ISA cards that use page flipping you
> could use a page fault trick to make it seem that the framebuffer is
> linear when it isn't. Since the framebuffer window is 64K when the page

This doesnt work. The DMA is direct, PCI DMA doesnt take page faults,
only CPU's do that. For sane cards do overlay mode, for stupid cards you
have to bounce the entire thing, you end up doing a two buffer

grab1 write2 to fb with CPU
grab2 write1 to fb with CPU
repeat

loop.

With ISA cards don't bother. You'll get 5-10fps at best even at low resolution.
You'd be better off reverse engineering an old DOS era cards drivers and
writing a feature connector mode card driver for something like the original
full length hauppauge card

Alan

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