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Commit 37a33026 authored by Heiko Carstens's avatar Heiko Carstens Committed by Linus Torvalds
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[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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 255acee7

Documentation/cpu-hotplug.txt

+6 −0
Original line number Diff line number Diff line
@@ -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

arch/s390/kernel/smp.c

+11 −3
Original line number Diff line number Diff line
@@ -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)

{