Re: Linux 2.6.39-rc3

[Yinghai Lu <yinghai@kernel.org>]

On 04/13/2011 10:21 AM, Joerg Roedel wrote:
> On Wed, Apr 13, 2011 at 08:46:09AM +0200, Ingo Molnar wrote:
> First of all, I bisected between v2.6.37-rc2..f005fe12b90c which where
> only a couple of patches and merged v2.6.38-rc4 in at every step. There
> was no failure found.
> Then I tried this again, but this time I merged v2.6.38-rc5 at every
> step and was successful. The bad commit in this branch turned out to be
> 
> 	1a4a678b12c84db9ae5dce424e0e97f0559bb57c
> 
> which is related to memblock.
> 
> Then I tried to find out which change between 2.6.38-rc4 and 2.6.38-rc5
> is needed to trigger the failure, so I used f005fe12b90c as a base,
> bisected between v2.6.38-rc4..v2.6.38-rc5 and merged every bisect step
> into the base and tested. Here the bad commit turned out to be
> 
> 	e6d2e2b2b1e1455df16d68a78f4a3874c7b3ad20
> 
> which is related to gart. It turned out that the gart aperture on that
> box is on another position with these patches. Before it was as
> 0xa4000000 and now it is at 0xa0000000. It seems like this has something
> to do with the root-cause.
> 
> Reverting commit 1a4a678b12c84db9ae5dce424e0e97f0559bb57c fixes the
> problem btw. and booting with iommu=soft also works, but I have no idea
> yet why the aperture at that address is a problem (with the patch
> reverted the aperture lands at 0x80000000).
> 
> I have put some debug-data online. There is my .config and two
> dmesg-files for good (==2.6.39-rc3 + revert) and bad (==2.6.39-rc3)
> I also created these dmesg-files again with memblock=debug, maybe that
> helps to find the problem. The files are at
> 
> 	http://www.8bytes.org/~joro/debug/

thanks for the bisecting...

so those two patches uncover some problems.

[    0.000000] Checking aperture...
[    0.000000] No AGP bridge found
[    0.000000] Node 0: aperture @ a0000000 size 32 MB
[    0.000000] Aperture pointing to e820 RAM. Ignoring.
[    0.000000] Your BIOS doesn't leave a aperture memory hole
[    0.000000] Please enable the IOMMU option in the BIOS setup
[    0.000000] This costs you 64 MB of RAM
[    0.000000]     memblock_x86_reserve_range: [0xa0000000-0xa3ffffff]       aperture64
[    0.000000] Mapping aperture over 65536 KB of RAM @ a0000000

so kernel try to reallocate apperture. because BIOS allocated is pointed to RAM or size is too small.

but your radeon does use [0xa0000000, 0xbfffffff)

[    4.281993] radeon 0000:01:05.0: VRAM: 320M 0x00000000C0000000 - 0x00000000D3FFFFFF (320M used)
[    4.290672] radeon 0000:01:05.0: GTT: 512M 0x00000000A0000000 - 0x00000000BFFFFFFF
[    4.298550] [drm] Detected VRAM RAM=320M, BAR=256M
[    4.309857] [drm] RAM width 32bits DDR
[    4.313748] [TTM] Zone  kernel: Available graphics memory: 1896524 kiB.
[    4.320379] [TTM] Initializing pool allocator.
[    4.324948] [drm] radeon: 320M of VRAM memory ready
[    4.329832] [drm] radeon: 512M of GTT memory ready.

and the one seems working:

[    0.000000] Checking aperture...
[    0.000000] No AGP bridge found
[    0.000000] Node 0: aperture @ a0000000 size 32 MB
[    0.000000] Aperture pointing to e820 RAM. Ignoring.
[    0.000000] Your BIOS doesn't leave a aperture memory hole
[    0.000000] Please enable the IOMMU option in the BIOS setup
[    0.000000] This costs you 64 MB of RAM
[    0.000000]     memblock_x86_reserve_range: [0x80000000-0x83ffffff]       aperture64
[    0.000000] Mapping aperture over 65536 KB of RAM @ 80000000
[    0.000000]     memblock_x86_reserve_range: [0xacb6bdc0-0xacb6bddf]          BOOTMEM

will use different position...

[    4.250159] radeon 0000:01:05.0: VRAM: 320M 0x00000000C0000000 - 0x00000000D3FFFFFF (320M used)
[    4.258830] radeon 0000:01:05.0: GTT: 512M 0x00000000A0000000 - 0x00000000BFFFFFFF
[    4.266742] [drm] Detected VRAM RAM=320M, BAR=256M
[    4.271549] [drm] RAM width 32bits DDR
[    4.275435] [TTM] Zone  kernel: Available graphics memory: 1896526 kiB.
[    4.282066] [TTM] Initializing pool allocator.
[    4.282085] usb 7-2: new full speed USB device number 2 using ohci_hcd
[    4.293076] [drm] radeon: 320M of VRAM memory ready
[    4.298277] [drm] radeon: 512M of GTT memory ready.
[    4.303218] [drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
[    4.309854] [drm] Driver supports precise vblank timestamp query.
[    4.315970] [drm] radeon: irq initialized.
[    4.320094] [drm] GART: num cpu pages 131072, num gpu pages 131072

So question is why radeon is using the address [0xa0000000 - 0xc000000], and in E820 it is RAM ....

[    0.000000]  BIOS-e820: 0000000000100000 - 00000000acb8d000 (usable)
[    0.000000]  BIOS-e820: 00000000acb8d000 - 00000000acb8f000 (reserved)
[    0.000000]  BIOS-e820: 00000000acb8f000 - 00000000afce9000 (usable)
[    0.000000]  BIOS-e820: 00000000afce9000 - 00000000afd21000 (reserved)
[    0.000000]  BIOS-e820: 00000000afd21000 - 00000000afd4f000 (usable)
[    0.000000]  BIOS-e820: 00000000afd4f000 - 00000000afdcf000 (reserved)
[    0.000000]  BIOS-e820: 00000000afdcf000 - 00000000afecf000 (ACPI NVS)
[    0.000000]  BIOS-e820: 00000000afecf000 - 00000000afeff000 (ACPI data)
[    0.000000]  BIOS-e820: 00000000afeff000 - 00000000aff00000 (usable)


so looks bios program wrong address to the radon card?

Thanks

Yinghai Lu