On Thu, 24 Jun 2010 21:51:40 +1200 Michael Cree mcree@orcon.net.nz wrote:
Is this a regression (what kernel version worked)?
Seems that the IOMMU can't find 128 pages. It's likely due to:
- out of the IOMMU space (possibly someone doesn't free the IOMMU space).
or
- the mapping parameters (such as align) aren't appropriate so the IOMMU can't find space.
I don't think KMS drivers have ever worked on alpha so its not a regression, they are working fine on x86 + powerpc and sparc has been run at least once.
KMS on the console boot up has worked since about 2.6.32, but starting up the X server has always failed and, in my case, the system becomes unstable and eventually OOPs.
I suspect we are simply hitting the limits of the iommu, how big an address space does it handle? since generally graphics drivers try to bind a lot of things to the GART.
No idea on the address space limit. I applied the patch of Fujita that logs all IOMMU allocations, and also inserted some extra printks in the ttm kernel code so that I could see which routines failed and the error code returned. Running the radeon test on boot exhibits the following:
[ 238.712768] [drm] Tested GTT->VRAM and VRAM->GTT copy for GTT offset 0x1a312000 [ 239.281127] [drm] Tested GTT->VRAM and VRAM->GTT copy for GTT offset 0x1a412000 [ 239.281127] ttm_tt_bind belched -12 [ 239.282104] ttm_bo_handle_move_mem belched -12 [ 239.282104] ttm_bo_move_buffer belched -12 [ 239.282104] ttm_bo_validate belched -12 [ 239.282104] radeon 0000:01:00.0: object_init failed for (1048576, 0x00000002) err=-12 [ 239.282104] [drm:radeon_test_moves] *ERROR* Failed to create GTT object 419 [ 239.399291] Error while testing BO move.
Note that no IOMMU allocations are printed while radeon_test_moves is running so iommu_arena_alloc doesn't appear to be called. Also the error code returned up to radeon_test_moves is -12 which is ENOMEM. So does appear to be some memory limit.
Hmm, not related with IOMMU? looks like ttm_tt_populate could return ENOMEM too. Can we locate where we hit ENOMEM first?