On Sun, Dec 12, 2021 at 01:12:05AM +0100, Thomas Gleixner wrote: > PCI/MSI and PCI/MSI-X are just implementations of IMS > > Not more, not less. The fact that they have very strict rules about the > storage space and the fact that they are mutually exclusive does not > change that at all. And the mess we have is that virtualiation broke this design. Virtualization made MSI/MSI-X special! I am wondering if we just need to bite the bullet and force the introduction of a new ACPI flag for the APIC that says one of: - message addr/data pairs work correctly (baremetal) - creating message addr/data pairs need to use a hypercall protocol - property not defined so assume only MSI/MSI-X/etc work. Intel was originally trying to do this with the 'IMS enabled' PCI Capability block, but a per PCI device capability is in the wrong layer. Jason
