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Diffstat (limited to 'Documentation/memory-hotplug.txt')
| -rw-r--r-- | Documentation/memory-hotplug.txt | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt index ce2cfcf35c27..443f4b44ad97 100644 --- a/Documentation/memory-hotplug.txt +++ b/Documentation/memory-hotplug.txt @@ -256,10 +256,27 @@ If the memory block is offline, you'll read "offline". 5.2. How to online memory ------------ -Even if the memory is hot-added, it is not at ready-to-use state. -For using newly added memory, you have to "online" the memory block. +When the memory is hot-added, the kernel decides whether or not to "online" +it according to the policy which can be read from "auto_online_blocks" file: -For onlining, you have to write "online" to the memory block's state file as: +% cat /sys/devices/system/memory/auto_online_blocks + +The default is "offline" which means the newly added memory is not in a +ready-to-use state and you have to "online" the newly added memory blocks +manually. Automatic onlining can be requested by writing "online" to +"auto_online_blocks" file: + +% echo online > /sys/devices/system/memory/auto_online_blocks + +This sets a global policy and impacts all memory blocks that will subsequently +be hotplugged. Currently offline blocks keep their state. It is possible, under +certain circumstances, that some memory blocks will be added but will fail to +online. User space tools can check their "state" files +(/sys/devices/system/memory/memoryXXX/state) and try to online them manually. + +If the automatic onlining wasn't requested, failed, or some memory block was +offlined it is possible to change the individual block's state by writing to the +"state" file: % echo online > /sys/devices/system/memory/memoryXXX/state |