On Tue, 12 May 2020 at 06:28, Alex Deucher <alexdeucher@xxxxxxxxx> wrote: > > On Mon, May 11, 2020 at 4:22 PM Al Dunsmuir <al.dunsmuir@xxxxxxxxxxxx> wrote: > > > > On Monday, May 11, 2020, 1:17:19 PM, "Christian König" wrote: > > > Hi guys, > > > > > 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... > > > > > 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. > > > > > Regards, > > > Christian. > > > > Christian, > > > > I would respectfully ask that this change be rejected. > > > > I'm currently an end user on both Intel (32-bit and 64-bit) and PPC > > (Macs, IBM Power - BE and LE). > > > > Linux is not just used for modern hardware. There is also a subset of > > the user base that uses it for what is often termed retro-computing. > > No it's not commercial usage, but no one can seriously claim that that > > Linux is for business only. > > > > Often the old hardware is built far batter than the modern junk, and > > will continue to run for years to come. This group of folks either has > > existing hardware they wish to continue to use, or are acquiring the > > same because they are tired of generic locked-down hardware. > > > > A significant percentage of the video hardware that falls in the retro > > category uses the AGP video bus. Removing that support for those cases > > where it works would severely limit performance and in some cases > > functionality. This can mean the difference between being able to run > > an application, or having it fail. > > > > Note there is no loss of functionality here, at least on radeon > hardware. It just comes down to which MMU gets used for access to > system memory, the AGP MMU on the chipset or the MMU built into the > GPU. On powerpc hardware, AGP has been particularly unstable, and AGP > has been disabled by default on radeon on powerpc for years now. In > fact, this will probably make older hardware more reliable as it takes > AGP out of the equation. > >From memory there is quite a loss in speed though, like pretty severe. The radeon PCI GART has a single slot TLB, if memory serves. I think this is going to be a hard sell at this stage, I'm guessing users will crawl out of the woodwork, I'm sure with 2 hours after I'm able to access the office, I can boot the 865 AGP box with an rv350 in it on a modern distro. Maybe we can find some way to compartmentalise AGP further? Dave. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
