X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fcpu-hotplug.txt;h=1bcf69996c9df74fba87c25949c05285ff604d3b;hb=39f8758259868a01ecad29b4379661dd3f21881f;hp=e71bc6cbbc5ec4935c16482c012b01ead3a57602;hpb=37a3302618a51520e2056494715ea6b4776dd8ab;p=linux-2.6

diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index e71bc6cbbc..1bcf69996c 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -46,10 +46,12 @@ 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, s390 only] use this to limit hotpluggable cpus.
-                          This option sets
+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
@@ -57,6 +59,9 @@ 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
@@ -92,13 +97,13 @@ at which time hotplug is disabled.
 
 You really dont need to manipulate any of the system cpu maps. They should
 be read-only for most use. When setting up per-cpu resources almost always use
-cpu_possible_map/for_each_cpu() to iterate.
+cpu_possible_map/for_each_possible_cpu() to iterate.
 
 Never use anything other than cpumask_t to represent bitmap of CPUs.
 
 #include <linux/cpumask.h>
 
-for_each_cpu              - Iterate over cpu_possible_map
+for_each_possible_cpu     - Iterate over cpu_possible_map
 for_each_online_cpu       - Iterate over cpu_online_map
 for_each_present_cpu      - Iterate over cpu_present_map
 for_each_cpu_mask(x,mask) - Iterate over some random collection of cpu mask.