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authorKumar Gala <galak@kernel.crashing.org>2006-03-20 18:58:02 +0100
committerKumar Gala <galak@kernel.crashing.org>2006-03-20 18:58:02 +0100
commit1a02e59a2970f9ed28ab51d3b08624b79e54d848 (patch)
tree470cce472be3b08c160e0c569648e7228651b12a /Documentation/cpu-hotplug.txt
parentppc32: Fix BCSR_SIZE for MPC834x SYS (diff)
parent[PATCH] powerpc: Fix bug in bug fix for bug in lmb_alloc() (diff)
downloadlinux-1a02e59a2970f9ed28ab51d3b08624b79e54d848.tar.xz
linux-1a02e59a2970f9ed28ab51d3b08624b79e54d848.zip
Merge branch 'master'
Diffstat (limited to 'Documentation/cpu-hotplug.txt')
-rw-r--r--Documentation/cpu-hotplug.txt27
1 files changed, 24 insertions, 3 deletions
diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 08c5d04f3086..57a09f99ecb0 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
-----------------