From: Heiko Carstens <[email protected]>
Introduce possible_cpus command line option. Hard sets the number of bits set
in cpu_possible_map. Unlike the additional_cpus parameter this one guarantees
that num_possible_cpus() will stay constant even if the system gets rebooted
and a different number of cpus are present at startup.
Signed-off-by: Heiko Carstens <[email protected]>
---
Documentation/cpu-hotplug.txt | 6 ++++++
arch/s390/kernel/smp.c | 14 +++++++++++---
2 files changed, 17 insertions(+), 3 deletions(-)
diff -purN a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
--- a/Documentation/cpu-hotplug.txt 2006-02-16 07:56:45.000000000 +0100
+++ b/Documentation/cpu-hotplug.txt 2006-02-16 08:00:39.000000000 +0100
@@ -50,6 +50,12 @@ additional_cpus=n [x86_64, s390 only] us
This option sets
cpu_possible_map = cpu_present_map + additional_cpus
+possible_cpus=n [s390 only] use this to set hotpluggable cpus.
+ This option sets possible_cpus bits in
+ cpu_possible_map. Thus keeping the numbers of bits set
+ constant even if the machine gets rebooted.
+ This option overrides additional_cpus.
+
CPU maps and such
-----------------
[More on cpumaps and primitive to manipulate, please check
diff -purN a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
--- a/arch/s390/kernel/smp.c 2006-02-16 07:56:45.000000000 +0100
+++ b/arch/s390/kernel/smp.c 2006-02-16 07:56:35.000000000 +0100
@@ -673,15 +673,16 @@ __cpu_up(unsigned int cpu)
}
static unsigned int __initdata additional_cpus;
+static unsigned int __initdata possible_cpus;
void __init smp_setup_cpu_possible_map(void)
{
unsigned int pcpus, cpu;
- pcpus = smp_count_cpus() + additional_cpus;
+ pcpus = min(smp_count_cpus() + additional_cpus, (unsigned int) NR_CPUS);
- if (pcpus > NR_CPUS)
- pcpus = NR_CPUS;
+ if (possible_cpus)
+ pcpus = min(possible_cpus, (unsigned int) NR_CPUS);
for (cpu = 0; cpu < pcpus; cpu++)
cpu_set(cpu, cpu_possible_map);
@@ -698,6 +699,13 @@ static int __init setup_additional_cpus(
}
early_param("additional_cpus", setup_additional_cpus);
+static int __init setup_possible_cpus(char *s)
+{
+ possible_cpus = simple_strtoul(s, NULL, 0);
+ return 0;
+}
+early_param("possible_cpus", setup_possible_cpus);
+
int
__cpu_disable(void)
{
-
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