On 3/4/22 12:43 PM, Christoph Hellwig wrote:

On Fri, Mar 04, 2022 at 12:36:17PM -0500, Boris Ostrovsky wrote:

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I bisected it to "x86: remove the IOMMU table infrastructure" but haven't actually looked at the code yet.

That looks like the swiotlb buffer did not get initialized at all, but I
can't really explain why.

Can you stick in a printk and see if xen_swiotlb_init_early gets called
at all?

Actually, that's the only thing I did do so far and yes, it does get called.

So, specifically for "x86: remove the IOMMU table infrastructure" I
think we need the one-liner below so that swiotlb_exit doesn't get called
for the Xen case.  But that should have been fixed up by the next
patch already.

This indeed allows dom0 to boot. Not sure I see where in the next patch this would have been fixed?


(BTW, just noticed in iommu_setup() you set this variable to 1. Should be 'true')


-boris