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-rw-r--r--Documentation/cpu-hotplug.txt17
1 files changed, 9 insertions, 8 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 94bbc27ddd4f..9d620c153b04 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -50,16 +50,17 @@ additional_cpus=n (*) Use this to limit hotpluggable cpus. This option sets
50 cpu_possible_map = cpu_present_map + additional_cpus 50 cpu_possible_map = cpu_present_map + additional_cpus
51 51
52(*) Option valid only for following architectures 52(*) Option valid only for following architectures
53- x86_64, ia64 53- ia64
54 54
55ia64 and x86_64 use the number of disabled local apics in ACPI tables MADT 55ia64 uses the number of disabled local apics in ACPI tables MADT to
56to determine the number of potentially hot-pluggable cpus. The implementation 56determine the number of potentially hot-pluggable cpus. The implementation
57should only rely on this to count the # of cpus, but *MUST* not rely on the 57should only rely on this to count the # of cpus, but *MUST* not rely
58apicid values in those tables for disabled apics. In the event BIOS doesn't 58on the apicid values in those tables for disabled apics. In the event
59mark such hot-pluggable cpus as disabled entries, one could use this 59BIOS doesn't mark such hot-pluggable cpus as disabled entries, one could
60parameter "additional_cpus=x" to represent those cpus in the cpu_possible_map. 60use this parameter "additional_cpus=x" to represent those cpus in the
61cpu_possible_map.
61 62
62possible_cpus=n [s390 only] use this to set hotpluggable cpus. 63possible_cpus=n [s390,x86_64] use this to set hotpluggable cpus.
63 This option sets possible_cpus bits in 64 This option sets possible_cpus bits in
64 cpu_possible_map. Thus keeping the numbers of bits set 65 cpu_possible_map. Thus keeping the numbers of bits set
65 constant even if the machine gets rebooted. 66 constant even if the machine gets rebooted.