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authorHeiko Carstens <heiko.carstens@de.ibm.com>2006-02-18 00:52:47 +0300
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-18 00:59:27 +0300
commit37a3302618a51520e2056494715ea6b4776dd8ab (patch)
tree379fd117bb816fd012dd58ba9c900e20792a8ae3
parent255acee706b333b79f593dd366f16e1f107cccc3 (diff)
downloadlinux-37a3302618a51520e2056494715ea6b4776dd8ab.tar.xz
[PATCH] s390: possible_cpus parameter
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 <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--Documentation/cpu-hotplug.txt6
-rw-r--r--arch/s390/kernel/smp.c14
2 files changed, 17 insertions, 3 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 4d3355da0e26..e71bc6cbbc5e 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -58,6 +58,12 @@ mark such hot-pluggable cpus as disabled entries, one could use this
parameter "additional_cpus=x" to represent those cpus in the cpu_possible_map.
+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 --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 53291e94ac7b..d0a2745aec7f 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -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(char *s)
}
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)
{