RE: AGP Chipset Support

Paul Sargent (Paul.Sargent@3dlabs.com)
Mon, 5 Jul 1999 20:09:34 +0100


That's not really a stupid question in the context of user space graphics
drivers, but I'm playing with kernel level abstraction (much like fbcon or
kgi) and one thing that interested me was getting AGP DMA to work + a few of
the other AGP specific functions.

As I understand it this involves some tweeking or the host chipset to set up
(although it looks like the BIOS should do this at start of day). Also there
is a address translation table called the GART which can be used for
scatter-gather type operations (although I'm informed Intel is not telling
anybody about how to use this at the moment).

And finally I've heard that any memory allocated which is going to be read
by AGP DMA has to be a special type.

You may notice that my above comments sound a little unsure of themselves.
That's because all of my information comes from people writing drivers under
Windows (NT or 95/8) so I don't know if these issues are really hardware
issues or MS-isms because they've (for example) decided to allocate AGP
memory out of a different pool.

So I was just looking for people who may have already touched on it.

Paul

> -----Original Message-----
> From: Michael B. Trausch [SMTP:mtrausch@wcnet.org]
> Sent: Monday, July 05, 1999 6:57 PM
> To: Paul Sargent
> Cc: Linux-Kernel
> Subject: Re: AGP Chipset Support
>
> -----BEGIN PGP SIGNED MESSAGE-----
>
> Hm... Well, I can say that I've run Linux on a few AGP machines, and can
> use vesafb on them. X is starting to work on support for them -- but just
> *why* would the kernel have to have AGP specific code? (Forgive me if
> that's a stupid question :).
>
>

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