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authorAshok Raj <ashok.raj@intel.com>2006-02-14 15:01:12 -0800
committerTony Luck <tony.luck@intel.com>2006-02-14 15:37:58 -0800
commita6b14fa6fdc01ab3519c2729624f808677539b59 (patch)
tree5bf76be44b0c9c7f80612ac71a1b1a4390decd7d /arch/ia64
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')
-rw-r--r--arch/ia64/kernel/acpi.c56
-rw-r--r--arch/ia64/kernel/setup.c4
2 files changed, 60 insertions, 0 deletions
diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index d2702c419cf..34795ede72e 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)
return (0);
}
+int additional_cpus __initdata = -1;
+
+static __init int setup_additional_cpus(char *s)
+{
+ if (s)
+ additional_cpus = simple_strtol(s, NULL, 0);
+
+ return 0;
+}
+
+early_param("additional_cpus", setup_additional_cpus);
+
+/*
+ * cpu_possible_map should be static, it cannot change as cpu's
+ * are onlined, or offlined. The reason is per-cpu data-structures
+ * are allocated by some modules at init time, and dont expect to
+ * do this dynamically on cpu arrival/departure.
+ * cpu_present_map on the other hand can change dynamically.
+ * In case when cpu_hotplug is not compiled, then we resort to current
+ * behaviour, which is cpu_possible == cpu_present.
+ * - Ashok Raj
+ *
+ * Three ways to find out the number of additional hotplug CPUs:
+ * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
+ * - The user can overwrite it with additional_cpus=NUM
+ * - Otherwise don't reserve additional CPUs.
+ */
+__init void prefill_possible_map(void)
+{
+ int i;
+ int possible, disabled_cpus;
+
+ disabled_cpus = total_cpus - available_cpus;
+ if (additional_cpus == -1) {
+ if (disabled_cpus > 0) {
+ possible = total_cpus;
+ additional_cpus = disabled_cpus;
+ }
+ else {
+ possible = available_cpus;
+ additional_cpus = 0;
+ }
+ } else {
+ possible = available_cpus + additional_cpus;
+ }
+ if (possible > NR_CPUS)
+ possible = NR_CPUS;
+
+ printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
+ possible,
+ max_t(int, additional_cpus, 0));
+
+ for (i = 0; i < possible; i++)
+ cpu_set(i, cpu_possible_map);
+}
+
int acpi_map_lsapic(acpi_handle handle, int *pcpu)
{
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 35f7835294a..3258e09278d 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -430,6 +430,7 @@ setup_arch (char **cmdline_p)
if (early_console_setup(*cmdline_p) == 0)
mark_bsp_online();
+ parse_early_param();
#ifdef CONFIG_ACPI
/* Initialize the ACPI boot-time table parser */
acpi_table_init();
@@ -688,6 +689,9 @@ void
setup_per_cpu_areas (void)
{
/* start_kernel() requires this... */
+#ifdef CONFIG_ACPI_HOTPLUG_CPU
+ prefill_possible_map();
+#endif
}
/*