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Re: 5.10.40 dom0 kernel - nvme: Invalid SGL for payload:131072 nents:13

Hi Jan,

On Wed, Jul 21, 2021 at 10:10:13AM +0200, Jan Beulich wrote:
> Since xen-blkback only talks in terms of bio-s, I don't think it is
> the party responsible for honoring such driver restrictions. Instead
> I'd expect the block layer's bio merging to be where this needs to be
> observed. Perhaps it simply doesn't expect to be passed requests in
> multiples of 11 sectors together with the capping at 64k (as said -
> iirc) and driver restrictions on where splits may occur? And as to
> earlier Linux versions working - perhaps the merging logic was less
> aggressive back then?

I later realised that there was another change in my setup besides
the kernel version going from 4.19 to 5.10: I gave the dom0 8GiB of
memory instead of the 3GiB it had before.

I understand that below 4GiB memory use of swiotlb is disabled so
all the time previously this was not used, and now is. Perhaps the
bug is in there?

I was told that the only simple way on a Xen dom0 to disable use of
swiotlb would be to set the memory below 4GiB again, so I might try

I was also pointed to this patch as a maybe fix for my issue:




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