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authorGlauber Costa <gcosta@redhat.com>2008-03-03 14:12:42 -0300
committerIngo Molnar <mingo@elte.hu>2008-04-17 17:40:53 +0200
commit68a1c3f8cd893f5c3c1396fec5be7d8acac4fc93 (patch)
tree9e68b2943f67912535b649a45a659ee1fc076aa2 /arch/x86/kernel/smpboot.c
parent7b1292e2371e3ae2ac69fbb899d539ddc7b53a27 (diff)
x86: move prefill_possible_map to common file
this patches moves prefill_possible_map() to smpboot.c Right now it is x86_64-specific, but nothing intrinsically prevents it to be used by i386 Signed-off-by: Glauber Costa <gcosta@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/smpboot.c')
-rw-r--r--arch/x86/kernel/smpboot.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
new file mode 100644
index 00000000000..bffe1086139
--- /dev/null
+++ b/arch/x86/kernel/smpboot.c
@@ -0,0 +1,53 @@
+#include <linux/init.h>
+#include <linux/smp.h>
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+int additional_cpus __initdata = -1;
+
+static __init int setup_additional_cpus(char *s)
+{
+ return s && get_option(&s, &additional_cpus) ? 0 : -EINVAL;
+}
+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.
+ * We do this because additional CPUs waste a lot of memory.
+ * -AK
+ */
+__init void prefill_possible_map(void)
+{
+ int i;
+ int possible;
+
+ if (additional_cpus == -1) {
+ if (disabled_cpus > 0)
+ additional_cpus = disabled_cpus;
+ else
+ additional_cpus = 0;
+ }
+ possible = num_processors + additional_cpus;
+ if (possible > NR_CPUS)
+ possible = NR_CPUS;
+
+ printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
+ possible, max_t(int, possible - num_processors, 0));
+
+ for (i = 0; i < possible; i++)
+ cpu_set(i, cpu_possible_map);
+}
+#endif
+