X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fcpu-hotplug.txt;h=b6d24c22274b8dfb0ea28c3e841594779f5b20e7;hb=5957a4eb284dd6f522b248b674792416466555b2;hp=4868c34f75090fe75b4f6bb28f70c7638540c4cd;hpb=0bd2af46839ad6262d25714a6ec0365db9d6b98f;p=pandora-kernel.git diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index 4868c34f7509..b6d24c22274b 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -54,8 +54,8 @@ additional_cpus=n (*) Use this to limit hotpluggable cpus. This option sets 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 +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 doesn't 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. @@ -217,14 +217,17 @@ Q: What happens when a CPU is being logically offlined? A: The following happen, listed in no particular order :-) - A notification is sent to in-kernel registered modules by sending an event - CPU_DOWN_PREPARE + CPU_DOWN_PREPARE or CPU_DOWN_PREPARE_FROZEN, depending on whether or not the + CPU is being offlined while tasks are frozen due to a suspend operation in + progress - All process is migrated away from this outgoing CPU to a new CPU - All interrupts targeted to this CPU is migrated to a new CPU - timers/bottom half/task lets are also migrated to a new CPU - Once all services are migrated, kernel calls an arch specific routine __cpu_disable() to perform arch specific cleanup. - Once this is successful, an event for successful cleanup is sent by an event - CPU_DEAD. + CPU_DEAD (or CPU_DEAD_FROZEN if tasks are frozen due to a suspend while the + CPU is being offlined). "It is expected that each service cleans up when the CPU_DOWN_PREPARE notifier is called, when CPU_DEAD is called its expected there is nothing @@ -242,9 +245,11 @@ A: This is what you would need in your kernel code to receive notifications. switch (action) { case CPU_ONLINE: + case CPU_ONLINE_FROZEN: foobar_online_action(cpu); break; case CPU_DEAD: + case CPU_DEAD_FROZEN: foobar_dead_action(cpu); break; }