On Tue, Dec 02, 2025 at 08:36:53PM +0400, Chris Li wrote: > On Tue, Dec 2, 2025 at 6:59 PM Jason Gunthorpe <[email protected]> wrote: > > The device is active > > during KHO, you CAN NOT do any resource reassignment, not bus numbers, > > not mmio. It must be fully disabled. > > I agree with Jason. The bus number is used in the low level hardware > to do the DMA transfer. The bus number can not change for a device > during livedupate with pending DMA transfer. The BDF MUST remain the > same as the liveupdate with DMA transfer requirement.
Thank you both for the explanation. > Another point is that, on the same machine it can have multiple PCI > host bridges. Each PCI host bridge bus number is acquired from the > ACPI table walk. I am not aware of any way to get the slot number of > the PCI host bridge. Lukas, do you know how to get the PCI host bridge > slot number to form a path? Host bridges are identified by the segment number. On ACPI-based systems, it's retrieved by acpi_pci_root_add() through invocation of the _SEG method. Thanks, Lukas
