On 27/06/10 16:20, FUJITA Tomonori wrote:
On Thu, 24 Jun 2010 21:51:40 +1200
Michael Cree<mcree@xxxxxxxxxxxx> 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?
Yeah, in ttm_mem_global_reserve while it is walking glob->zones:
[ 239.303588] [drm] Tested GTT->VRAM and VRAM->GTT copy for GTT offset
0x1a412000
[ 239.304564] ttm_mem_global_reserve zone used_mem (0x1a5f0000) exceeds
limit (0x1a5ef000)
[ 239.304564] ttm_mem_global_reserve zone used_mem (0x1a5f0000) exceeds
limit (0x1a5ef000)
[ 239.304564] ttm_mem_global_reserve zone used_mem (0x1a5f0000) exceeds
limit (0x1a5ef000)
[ 239.304564] ttm_mem_global_reserve zone used_mem (0x1a5f0000) exceeds
limit (0x1a5ef000)
[ 239.304564] ttm_mem_global_reserve zone used_mem (0x1a5f0000) exceeds
limit (0x1a5ef000)
[ 239.304564] ttm_mem_global_reserve return non-zero count decs to zero
[ 239.304564] ttm_mem_global_alloc_page belched -12
[ 239.304564] __ttm_tt_get_page coughed NULL
[ 239.304564] ttm_tt_populate belched -12
[ 239.304564] ttm_tt_bind belched -12
[ 239.304564] ttm_bo_handle_move_mem belched -12
[ 239.304564] ttm_bo_move_buffer belched -12
[ 239.304564] ttm_bo_validate belched -12
On a hunch that we are chasing a red herring I installed another 256MB
of memory into the machine (was 576MB for the test reported above) for a
total of 832MB.
Now radeon_test_moves runs to completion without error.
OK, now a test of starting up the X server - ah, a bus error again but
now it looks like it's in the radeon driver:
[ 1435.014] (II) EXA(0): Driver allocated offscreen pixmaps
[ 1435.014] (II) EXA(0): Driver registered support for the following
operations:
[ 1435.014] (II) Solid
[ 1435.014] (II) Copy
[ 1435.014] (II) Composite (RENDER acceleration)
[ 1435.014] (II) UploadToScreen
[ 1435.014] (II) DownloadFromScreen
[ 1435.030]
Backtrace:
[ 1435.032] 0: /opt/xorg-ev56/bin/X (xorg_backtrace+0x54) [0x120070884]
[ 1435.032] 1: /opt/xorg-ev56/bin/X (0x120000000+0x65608) [0x120065608]
[ 1435.033] 2: /lib/libc.so.6.1 (0x20000310000+0x3d610) [0x2000034d610]
[ 1435.034] 3: /opt/xorg-ev56/lib/xorg/modules/drivers/radeon_drv.so
(0x20000758000+0x15b890) [0x200008b3890]
[ 1435.034] 4: /opt/xorg-ev56/lib/xorg/modules/drivers/radeon_drv.so
(0x20000758000+0x1392a0) [0x200008912a0]
[ 1435.034] 5: /opt/xorg-ev56/lib/xorg/modules/drivers/radeon_drv.so
(0x20000758000+0x139bec) [0x20000891bec]
[ 1435.034] 6: /opt/xorg-ev56/lib/xorg/modules/drivers/radeon_drv.so
(0x20000758000+0x4f088) [0x200007a7088]
[ 1435.035] 7: /opt/xorg-ev56/lib/xorg/modules/drivers/radeon_drv.so
(0x20000758000+0x16f0f8) [0x200008c70f8]
[ 1435.035] 8: /opt/xorg-ev56/bin/X (AddScreen+0x1c0) [0x1200532b0]
[ 1435.036] 9: /opt/xorg-ev56/bin/X (InitOutput+0x29c) [0x12008c6ec]
[ 1435.036] 10: /opt/xorg-ev56/bin/X (0x120000000+0x24b48) [0x120024b48]
[ 1435.037] 11: /lib/libc.so.6.1 (__libc_start_main+0xec) [0x2000033267c]
[ 1435.037] 12: /opt/xorg-ev56/bin/X (__start+0x38) [0x120024788]
[ 1435.038] Bus error at address 0x20000030000
And nothing in dmesg. Now I'm not triggering the nasty page alloc errors.
Cheers
Michael.
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