Re: [PATCH v2 03/22] PCI: Inherit bus numbers from previous kernel during Live Update

Jason Gunthorpe
2026-03-01T19:22:44Z

On Fri, Feb 27, 2026 at 09:04:49AM -0700, Alex Williamson wrote:

> Not only fabric topology, but also routing.

Yes

> ACS overrides on the
> command line would need to be enforced between the original and kexec
> kernel such that IOMMU groups are deterministic. Thanks,

That's a good point, I think as a reasonable starting point we should
require live update preserved devices to have singleton iommu_groups
on both sides. That is easy to check and enforce, and it doesn't
matter how the administrator makes that happen.

You also can't change the ACS flags while traffic is flowing because
that changes the fabric routing too. This should take care to enforce
that restriction as well.

Jason