[RFC] Remove AGP support from Radeon/Nouveau/TTM

[John Paul Adrian Glaubitz]

Hi Christian!

> Well let's face it AGP is a total headache to maintain and dead for at least 10+ years.
>
> We have a lot of x86 specific stuff in the architecture independent graphics memory management
> to get the caching right, abusing the DMA API on multiple occasions, need to distinct between
> AGP and driver specific page tables etc etc...

AGP isn't exclusively used on x86 but there are also a lot of PowerPC desktop machines (Apple
PowerMac, Pegasos etc) that employ AGP graphics.

> So the idea here is to just go ahead and remove the support from Radeon and Nouveau and
> then drop the necessary code from TTM.
> For Radeon this means that we just switch over to the driver specific page tables and
> everything should more or less continue to work.
>
> For Nouveau I'm not 100% sure, but from the code it of hand looks like we can do it similar to Radeon.
>
> Please comment what you think about this.

I would be against such a move as AGP graphics is still used by people running the powerpc
and ppc64 Debian ports on their vintage hardware [1].

I have also CC'ed the debian-powerpc mailing list so that other users can voice their
opinion.

Thanks,
Adrian

> [1] https://cdimage.debian.org/cdimage/ports/2020-04-19/

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz at debian.org
`. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
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