What a stupid move by them - no, not only will we be forced to PCI, but it’s a WARNING SIGN - Linux is ending PowerPC support - while my Quad G5 has Nvidia and it’s still a PIA to set up (continue to get blank splash screen or black screen), 2 of my PPC machines - a PB G4 DLSD and G4 upgraded Pismo use Radeon cards.
No, what the developers are doing is forcing us to stop using PPC for Linux.
Wrong.
As usual Phoronix has a tendency for overblown flame-bait headlines. In this case the developer proposing the change used VERY poor wording on the subject line, and Michael just ran with that.
i posted in the driver mailing list and the reply clarified that they are looking to use the PCI GART (MMU) on the card instead of the AGP bus GART. This is already the default mode of operation on PPC.
Today’s follow up article explained that AGP bus still is used for the full benefit of faster data transfers, but the caching and DMA operations will tend to be saner using the PCI bus GART. It is worth the read of the comments.
Some folks on the mailing lists do have the useless “If it ain’t new and shiny you should throw it away” attitude. Others understand the need to keep older hardware running... and especially running well. The tech leads seem sane and do want to move forwards and keep the older hardware support. They believe this change will simplify the code, improve stability and enable future improvements.
The consensus was that the PPC code was in better shape in this area than the generic (x86) code in terms of optimization and performance. The goal will be to come up with one optimized version and move forwards with improvements without the memory access errors that the AGP GART tends to induce. One gent’s comment today on Phoronix indicated for one Intel chipset the CPU load was a bit higher, throughput (frame rate) the same, but the Intel motherboard chipset + x86 PCI code had stability issues.
In the longer term, this has the potential to correct things like PPC Nouveau incompatibility with PPC64 page sizes >4KB.
The PPC Mac community does need to help on an ongoing basis, not just consume. Support your distributions, test, report bugs and help validate fixes.
I’ve built up a collection of PC, Mac and AIX video cards (often both flavours so endian bugs can be identified and fixed) and plan to get involved with driver testing and eventually driver development.
Hope this helps
Al Dunsmuir
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@Macbookprodude This has nothing to do with PowerPC directly. AGP cards will remain completely usable - the AGP slot will effectively just turn into 66mhz PCI (to my understanding).
PowerPC might not change at all, as one user explains in the replies section ...
The default is to not use the AGP GART on PPC, but there is code still there to support it. Since it is apparently different than the x86 code AND not used much, it tends not to work well when enabled - the worst of both worlds.
The more folks who know this area of hardware and software talk, the more it sounds like the RFC is reasonable and likely a win in the end for PPC as more code becomes common across platforms.
Al Dunsmuir
