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

David Matlack
2026-02-25T23:20:20Z

On 2026-02-25 04:47 PM, Bjorn Helgaas wrote:
> On Thu, Jan 29, 2026 at 09:24:50PM +0000, David Matlack wrote:
> > Inherit bus numbers from the previous kernel during a Live Update when
> > one or more PCI devices are being preserved. This is necessary so that
> > preserved devices can DMA through the IOMMU during a Live Update
> > (changing bus numbers would break IOMMU translation).
>
> I think changing bus numbers would break DMA regardless of whether an
> IOMMU is involved. Completions carrying the data for DMA reads are
> routed back to the Requester ID of the read.

Ahh, makes sense. I'll clarify the commit message in the next version.