Hi Bjorn, On Tue, Jul 16, 2024 at 5:45 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > I think Linux is missing some important _HPX functionality. Per ACPI > r6.5, sec 6.2.9, > > OSPM uses the information returned by _HPX to determine how to > configure PCI Functions that are hot-plugged into the system, to > configure Functions not configured by the platform firmware during > initial system boot, and to configure Functions any time they lose > configuration space settings (e.g. OSPM issues a Secondary Bus > Reset/Function Level Reset or Downstream Port Containment is > triggered). > > Linux currently *does* process _HPX for hot-added devices. > > The spec doesn't call it out for boot-time enumeration, except for > "Functions not configured by the platform firmware during initial > system boot", but Linux does process _HPX for all devices enumerated > at boot-time because it's not clear how to identify devices that > weren't configured by firmware. > > But AFAICT, Linux does not do anything with _HPX in the device reset, > AER, or DPC flows. I don't have any problem reports that I can say > are caused by lack of _HPX after reset, but it seems like something we > should fix. The consumer grade devices I checked don't have _HPX in the ACPI ASL. So I can't really delve into it any further. Kai-Heng > > If we could find a system with _HPX that does something interesting, > we might be able to demonstrate a defect by looking at a device before > and after a reset. > > Bjorn
