On 9/10/19 4:36 PM, Igor Druzhinin wrote: > On 10/09/2019 18:48, Boris Ostrovsky wrote: >> On 9/10/19 5:46 AM, Igor Druzhinin wrote: >>> On 10/09/2019 02:47, Boris Ostrovsky wrote: >>>> On 9/9/19 5:48 PM, Igor Druzhinin wrote: >>>>> On 09/09/2019 20:19, Boris Ostrovsky wrote: >>>>> >>>>>> The other question I have is why you think it's worth keeping >>>>>> xen_mcfg_late() as a late initcall. How could MCFG info be updated >>>>>> between acpi_init() and late_initcalls being run? I'd think it can only >>>>>> happen when a new device is hotplugged. >>>>>> >>>>> It was a precaution against setup_mcfg_map() calls that might add new >>>>> areas that are not in MCFG table but for some reason have _CBA method. >>>>> It's obviously a "firmware is broken" scenario so I don't have strong >>>>> feelings to keep it here. Will prefer to remove in v2 if you want. >>>> Isn't setup_mcfg_map() called before the first xen_add_device() which is >>>> where you are calling xen_mcfg_late()? >>>> >>> setup_mcfg_map() calls are done in order of root bus discovery which >>> happens *after* the previous root bus has been enumerated. So the order >>> is: call setup_mcfg_map() for root bus 0, find that >>> pci_mmcfg_late_init() has finished MCFG area registration, perform PCI >>> enumeration of bus 0, call xen_add_device() for every device there, call >>> setup_mcfg_map() for root bus X, etc. >> Ah, yes. Multiple busses. >> >> If that's the case then why don't we need to call xen_mcfg_late() for >> the first device on each bus? >> > Ideally, yes - we'd like to call it for every bus discovered. But boot > time buses are already in MCFG (otherwise system boot might not simply > work as Jan pointed out) so it's not strictly required. The only case is > a potential PCI bus hot-plug but I'm not sure it actually works in > practice and we certainly didn't support it before. It might be solved > theoretically by subscribing to acpi_bus_type that is available after > acpi_init().
OK. Then *I think* we can drop late_initcall() but I would really like to hear when others think. -boris _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
