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authorAshok Raj <ashok.raj@intel.com>2006-02-14 18:01:12 -0500
committerTony Luck <tony.luck@intel.com>2006-02-14 18:37:58 -0500
commita6b14fa6fdc01ab3519c2729624f808677539b59 (patch)
tree5bf76be44b0c9c7f80612ac71a1b1a4390decd7d /arch/ia64/kernel/acpi.c
parent69aa234b918c0d9bc4a20cd6d4453aaa3418f457 (diff)
[IA64] Count disabled cpus as potential hot-pluggable CPUs
Have a facility to account for potentially hot-pluggable CPUs. ACPI doesnt give a determinstic method to find hot-pluggable CPUs. Hence we use 2 methods to assist. - BIOS can mark potentially hot-pluggable CPUs as disabled in the MADT tables. - User can specify the number of hot-pluggable CPUs via parameter additional_cpus=X The option is enabled only if ACPI_CONFIG_HOTPLUG_CPU=y which enables the physical hotplug option. Without which user can still use logical onlining and offlining of CPUs by enabling CONFIG_HOTPLUG_CPU=y Adds more bits to cpu_possible_map for potentially hot-pluggable cpus. Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel/acpi.c')
-rw-r--r--arch/ia64/kernel/acpi.c56
1 files changed, 56 insertions, 0 deletions
diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index d2702c419cf8..34795ede72e0 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -761,6 +761,62 @@ int acpi_map_cpu2node(acpi_handle handle, int cpu, long physid)
761 return (0); 761 return (0);
762} 762}
763 763
764int additional_cpus __initdata = -1;
765
766static __init int setup_additional_cpus(char *s)
767{
768 if (s)
769 additional_cpus = simple_strtol(s, NULL, 0);
770
771 return 0;
772}
773
774early_param("additional_cpus", setup_additional_cpus);
775
776/*
777 * cpu_possible_map should be static, it cannot change as cpu's
778 * are onlined, or offlined. The reason is per-cpu data-structures
779 * are allocated by some modules at init time, and dont expect to
780 * do this dynamically on cpu arrival/departure.
781 * cpu_present_map on the other hand can change dynamically.
782 * In case when cpu_hotplug is not compiled, then we resort to current
783 * behaviour, which is cpu_possible == cpu_present.
784 * - Ashok Raj
785 *
786 * Three ways to find out the number of additional hotplug CPUs:
787 * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
788 * - The user can overwrite it with additional_cpus=NUM
789 * - Otherwise don't reserve additional CPUs.
790 */
791__init void prefill_possible_map(void)
792{
793 int i;
794 int possible, disabled_cpus;
795
796 disabled_cpus = total_cpus - available_cpus;
797 if (additional_cpus == -1) {
798 if (disabled_cpus > 0) {
799 possible = total_cpus;
800 additional_cpus = disabled_cpus;
801 }
802 else {
803 possible = available_cpus;
804 additional_cpus = 0;
805 }
806 } else {
807 possible = available_cpus + additional_cpus;
808 }
809 if (possible > NR_CPUS)
810 possible = NR_CPUS;
811
812 printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
813 possible,
814 max_t(int, additional_cpus, 0));
815
816 for (i = 0; i < possible; i++)
817 cpu_set(i, cpu_possible_map);
818}
819
764int acpi_map_lsapic(acpi_handle handle, int *pcpu) 820int acpi_map_lsapic(acpi_handle handle, int *pcpu)
765{ 821{
766 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL }; 822 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };