On Wed, June 22, 2016 10:54 PM Bjorn Helgaas wrote: > On Wed, Jun 22, 2016 at 03:13:32PM +0800, Rui Wang wrote: > > On Friday, June 17, 2016 1:10 AM, Bjorn Helgaas wrote: > > > ioapic_insert_resources() is x86-specific, but I'm not sure why; it > > > seems like it does things that should be applicable to ia64 as well. > > > > > > acpi_ioapic_add() is not x86-specific, and it is called from > > > acpi_pci_root_add() for the hot-add case. You're adding an > > > x86-xpecific call in pci_assign_unassigned_resources(). Why should > > > the hot-add case be for all arches, but the boot-time case only for x86? > > > > Hi Bjorn, > > > > It turns out that IOAPIC hotplug has not been pursued on ia64. There > > were demos showing CPU sockets online/offline on ia64 but the CPUs had > > no IIO, thus no IOAPIC hotplug. > > That doesn't mean we need to write code that's gratuitously x86-specific. > > > So to answer the first question: > > ioapic_insert_resources() is x86-specific because it's inserting what > > has been setup in io_apic_init_mappings() which, through > > mpc_ioapic_addr(), is capable of handling both the static case > > (acpi_parse_ioapic(), etc.) and the hotplug case (acpi_ioapic_add()). > > But on ia64, there's only the static case through acpi_parse_iosapic(), no > need for the hotplug case yet. > > ioapic_insert_resources() inserts IOAPIC resources on x86. Where are > IOSAPIC resources inserted on ia64? > I'm not sure. Its physical address from MADT is parsed in acpi_parse_iosapic() and ioremap()'d in iosapic_init(). Only the virtual address is recorded. The physical address doesn't seem to be recorded and inserted explicitly. But it could be in a "_CRS" and gets inserted implicitly. The iosapic on ia64 uses its own data structures very different from the ioapic on x86. I think it's hard to unify them using a common set of functions, without rewriting the whole framework. Thanks Rui -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
