----- Original Message ----- > From: "Felix Kuehling" <felix.kuehling@xxxxxxx> > To: "Timothy Pearson" <tpearson@xxxxxxxxxxxxxxxxxxxxx> > Cc: "amd-gfx" <amd-gfx@xxxxxxxxxxxxxxxxxxxxx> > Sent: Monday, November 25, 2019 3:34:20 PM > Subject: Re: [PATCH 1/1] amdgpu: Enable KFD on POWER systems > On 2019-11-25 4:06 p.m., Timothy Pearson wrote: >> >> ----- Original Message ----- >>> From: "Felix Kuehling" <felix.kuehling@xxxxxxx> >>> To: "Timothy Pearson" <tpearson@xxxxxxxxxxxxxxxxxxxxx>, "amd-gfx" >>> <amd-gfx@xxxxxxxxxxxxxxxxxxxxx> >>> Sent: Monday, November 25, 2019 11:07:31 AM >>> Subject: Re: [PATCH 1/1] amdgpu: Enable KFD on POWER systems >>> Hi Timothy, >>> >>> Thank you for the patch and for confirming that it works. We did some >>> experimental work on Power8 a few years ago. I see that Talos II is Power9. >>> >>> At the time we were working on Power8 we had to add some #ifdef >>> CONFIG_ACPI guards around some ACPI-specific code in KFD. Do you know to >>> what extent ACPI is available and working on the Power architecture? >>> >>> Another problem we ran into with Power, is the physical address map. >>> System memory can be a physical addresses outside the range accessible >>> by the GPU. Vega has 44-bit physical addressing. Older Polaris GPUs only >>> have 40-bits. Did you run into any such problems? Do you need an IOMMU >>> to make system memory accessible to the GPU? >>> >>> Regards, >>> Felix >> Yes, we are POWER9. It looks like the ACPI guards are no longer required; as >> you have surmised, POWER does not use ACPI (the equivalent is OPAL, which is a >> different interface entirely). What were the APCI calls used for? There may >> be OPAL equivalents that could be added in to replace them and provide similar >> functionality. > > There are some ACPI calls (e.g. acpi_get_table) in kfd_crat.c for > getting a CRAT table from ACPI. This is only useful for AMD APUs, which > are x86_64. We don't need this for discrete GPUs because on non-APU > systems there is no CRAT table and we build our own. If you can compile > the code without problems on Power and with CONFIG_ACPI not defined, > then I guess this is no longer an issue. Sounds reasonable -- yes, it compiles without issue so I think we're good to go. > >> Kernel 5.4 enables a > 32-bit and <=64-bit bypass mode for POWER. This is one >> reason we came back and revisited the KFD/ROCm functionality on POWER; as it >> turns out, after fixing up the userspace tools KFD is indeed functional on >> POWER with 5.4-rc8 and above. My understanding is that the POWER IOMMU is used >> as a lightweight translation layer between the 64-bit host and the 40/44-bit >> GPU. >> >> I'm working on getting a Debian PPA set up for POWER to make the userspace tools >> easier to obtain for testing, but progress is slow due to lack of Debian source >> packages. Probably the easiest way to replicate / test this with HIP is to use >> the AOMP repository with my modifications; pull requests are already in place >> on Github for most of the userspace tooling updates. >> >> Thank you! > Thanks, > Felix > > > _______________________________________________ > amd-gfx mailing list > amd-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/amd-gfx _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
