Hi.

Managed to get the Radeon R300 running on mesa 11.1.1 with an old 2013 patch from Michel Dànzer, next problem is of course enabling agpmode, running with pci-mode with radeon.agpmode=-1 works, but is of course slow, and seems to load the cpu a lot.

Upon initial investigation i could not initially believe agp could be this this broken for this long, until i found this.

"committed with Ben Skeggs on Feb 26, 2013"

https://github.com/DespairFactor/bullhead/commit/650e1203c11354ba84d69ba445abc0efcfe3890a

http://lxr.free-electrons.com/source/drivers/gpu/drm/nouveau/nouveau_agp.c?v=4.2

#ifdef __powerpc__

/* Disable AGP by default on all PowerPC machines for

* now -- At least some UniNorth-2 AGP bridges are

* known to be broken: DMA from the host to the card

* works just fine, but writeback from the card to the

* host goes straight to memory untranslated bypassing

* the GATT somehow, making them quite painful to deal

* with...

if (nouveau_agpmode == -1)

return false;

#endif

and now later this:

https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/nouveau/nvkm/subdev/pci/agp.c

#ifdef __powerpc__

/* Disable AGP by default on all PowerPC machines for now -- At

* least some UniNorth-2 AGP bridges are known to be broken:

* DMA from the host to the card works just fine, but writeback

* from the card to the host goes straight to memory

* untranslated bypassing that GATT somehow, making them quite

* painful to deal with...

mode = 0;

#endif

All seems to point to serious issues had around the time of change to ums to kms and a serious regression hitting the linux kernel? No?

Cheers

-Mike