Re: Linux 2.6.39-rc3

["H. Peter Anvin" <hpa@zytor.com>]

On 04/13/2011 10:21 AM, Joerg Roedel 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).
> 

Does reverting e6d2e2b2b1e1455df16d68a78f4a3874c7b3ad20 solve the
problem for you?

1a4a678b12c84db9ae5dce424e0e97f0559bb57c is a memory-allocation-order
patch, which have a nasty tendency to unmask bugs elsewhere in the
kernel.  However, e6d2e2b2b1e1455df16d68a78f4a3874c7b3ad20 looks
positively strange (and it doesn't exactly help that the description is
written in Yinghai-ese and is therefore nearly impossible to decode,
never mind tell if it is remotely correct.)

	-hpa