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. 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. To answer the second question: acpi_ioapic_add() is in effect x86-specific, because it's an empty function when CONFIG_ACPI_HOTPLUG_IOAPIC isn't defined. And CONFIG_ACPI_HOTPLUG_IOAPIC depends on CONFIG_X86_IO_APIC (see drivers/acpi/Kconfig). This was introduced in c183619b6 (x86/irq, ACPI: Implement ACPI driver to support IOAPIC hotplug). That commit shows the dependency. I'll send a newer version with comments explaining these. 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
