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Diffstat (limited to 'Documentation/cpu-hotplug.txt')
| -rw-r--r-- | Documentation/cpu-hotplug.txt | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index 08c5d04f308600..57a09f99ecb089 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -11,6 +11,8 @@ Joel Schopp <jschopp@austin.ibm.com> ia64/x86_64: Ashok Raj <ashok.raj@intel.com> + s390: + Heiko Carstens <heiko.carstens@de.ibm.com> Authors: Ashok Raj <ashok.raj@intel.com> Lots of feedback: Nathan Lynch <nathanl@austin.ibm.com>, @@ -44,9 +46,28 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using maxcpus=2 will only boot 2. You can choose to bring the other cpus later online, read FAQ's for more info. -additional_cpus=n [x86_64 only] use this to limit hotpluggable cpus. - This option sets - cpu_possible_map = cpu_present_map + additional_cpus +additional_cpus*=n Use this to limit hotpluggable cpus. This option sets + cpu_possible_map = cpu_present_map + additional_cpus + +(*) Option valid only for following architectures +- x86_64, ia64, s390 + +ia64 and x86_64 use the number of disabled local apics in ACPI tables MADT +to determine the number of potentially hot-pluggable cpus. The implementation +should only rely on this to count the #of cpus, but *MUST* not rely on the +apicid values in those tables for disabled apics. In the event BIOS doesnt +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. + +s390 uses the number of cpus it detects at IPL time to also the number of bits +in cpu_possible_map. If it is desired to add additional cpus at a later time +the number should be specified using this option or the possible_cpus option. + +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 ----------------- |