Re: GGI, EGCS/PGCC, Kernel source

Alan Cox (
Wed, 25 Feb 1998 21:33:00 +0000 (GMT)

> so what will do in the kernel? eat cpu cycles while polling? schedule to
> other processes (much too heavyweight)? XFree86 does not wait after
> queuing a command, it continues and prepares parameters for the next one,
> and waits only if the queue is full.

Well I'd assume thats how we'd handle it - I queue 50 operations, thats
what 5000 clocks. Its not worth rescheduling for that.

> you can not pull such MMU stunts for the _same_ process. The problem is
> framebuffer access from the _same_ process. You can not touch _any_ of the
> framebuffer when an accelerated command is running (on most cards). You
> can touch it shortly after it's finished. XFree86 + XAA has no such
> problems, as all of X's code is behaving 'nicely'.

Firstly if its short operations then I'll have finished the ops before
I get back. Secondly if its not I can flip the mmu state of those pages
and block on fault the task.


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