On Wed, Nov 30, 2022 at 7:54 AM Robin Murphy <robin.murphy@xxxxxxx> wrote: > > On 2022-11-29 17:11, Mikhail Krylov wrote: > > On Tue, Nov 29, 2022 at 11:05:28AM -0500, Alex Deucher wrote: > >> On Tue, Nov 29, 2022 at 10:59 AM Mikhail Krylov <sqarert@xxxxxxxxx> wrote: > >>> > >>> On Tue, Nov 29, 2022 at 09:44:19AM -0500, Alex Deucher wrote: > >>>> On Mon, Nov 28, 2022 at 3:48 PM Mikhail Krylov <sqarert@xxxxxxxxx> wrote: > >>>>> > >>>>> On Mon, Nov 28, 2022 at 09:50:50AM -0500, Alex Deucher wrote: > >>>>> > >>>>>>>> [excessive quoting removed] > >>>>> > >>>>>>> So, is there any progress on this issue? I do understand it's not a high > >>>>>>> priority one, and today I've checked it on 6.0 kernel, and > >>>>>>> unfortunately, it still persists... > >>>>>>> > >>>>>>> I'm considering writing a patch that will allow user to override > >>>>>>> need_dma32/dma_bits setting with a module parameter. I'll have some time > >>>>>>> after the New Year for that. > >>>>>>> > >>>>>>> Is it at all possible that such a patch will be merged into kernel? > >>>>>>> > >>>>>> On Mon, Nov 28, 2022 at 9:31 AM Mikhail Krylov <sqarert@xxxxxxxxx> wrote: > >>>>>> Unless someone familiar with HIMEM can figure out what is going wrong > >>>>>> we should just revert the patch. > >>>>>> > >>>>>> Alex > >>>>> > >>>>> > >>>>> Okay, I was suggesting that mostly because > >>>>> > >>>>> a) it works for me with dma_bits = 40 (I understand that's what it is > >>>>> without the original patch applied); > >>>>> > >>>>> b) there's a hint of uncertainity on this line > >>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/radeon/radeon_device.c#n1359 > >>>>> saying that for AGP dma_bits = 32 is the safest option, so apparently there are > >>>>> setups, unlike mine, where dma_bits = 32 is better than 40. > >>>>> > >>>>> But I'm in no position to argue, just wanted to make myself clear. > >>>>> I'm okay with rebuilding the kernel for my machine until the original > >>>>> patch is reverted or any other fix is applied. > >>>> > >>>> What GPU do you have and is it AGP? If it is AGP, does setting > >>>> radeon.agpmode=-1 also fix it? > >>>> > >>>> Alex > >>> > >>> That is ATI Radeon X1950, and, unfortunately, radeon.agpmode=-1 doesn't > >>> help, it just makes 3D acceleration in games such as OpenArena stop > >>> working. > >> > >> Just to confirm, is the board AGP or PCIe? > >> > >> Alex > > > > It is AGP. That's an old machine. > > Can you check whether dma_addressing_limited() is actually returning the > expected result at the point of radeon_ttm_init()? Disabling highmem is > presumably just hiding whatever problem exists, by throwing away all > >32-bit RAM such that use_dma32 doesn't matter. The device in question only supports a 32 bit DMA mask so dma_addressing_limited() should return true. Bounce buffers are not really usable on GPUs because they map so much memory. If dma_addressing_limited() returns false, that would explain it. Alex
