smp: Use nr_cpus= to set nr_cpu_ids early
On x86, before prefill_possible_map(), nr_cpu_ids will be NR_CPUS aka
CONFIG_NR_CPUS.
Add nr_cpus= to set nr_cpu_ids. so we can simulate cpus <=8 are installed on
normal config.
-v2: accordging to Christoph, acpi_numa_init should use nr_cpu_ids in stead of
NR_CPUS.
-v3: add doc in kernel-parameters.txt according to Andrew.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <1265793639-15071-34-git-send-email-yinghai@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index 40574ae..605a08b 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -881,8 +881,8 @@
possible = available_cpus + additional_cpus;
- if (possible > NR_CPUS)
- possible = NR_CPUS;
+ if (possible > nr_cpu_ids)
+ possible = nr_cpu_ids;
printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
possible, max((possible - available_cpus), 0));
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 678d0b8..eff2fe1 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1213,11 +1213,12 @@
total_cpus = max_t(int, possible, num_processors + disabled_cpus);
- if (possible > CONFIG_NR_CPUS) {
+ /* nr_cpu_ids could be reduced via nr_cpus= */
+ if (possible > nr_cpu_ids) {
printk(KERN_WARNING
"%d Processors exceeds NR_CPUS limit of %d\n",
- possible, CONFIG_NR_CPUS);
- possible = CONFIG_NR_CPUS;
+ possible, nr_cpu_ids);
+ possible = nr_cpu_ids;
}
printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",