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Diffstat (limited to 'Documentation/memory-hotplug.txt')
| -rw-r--r-- | Documentation/memory-hotplug.txt | 47 |
1 files changed, 31 insertions, 16 deletions
diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt index 57e7e9cc187..8f485d72cf2 100644 --- a/Documentation/memory-hotplug.txt +++ b/Documentation/memory-hotplug.txt @@ -126,36 +126,51 @@ config options. -------------------------------- 4 sysfs files for memory hotplug -------------------------------- -All sections have their device information under /sys/devices/system/memory as +All sections have their device information in sysfs. Each section is part of +a memory block under /sys/devices/system/memory as /sys/devices/system/memory/memoryXXX -(XXX is section id.) +(XXX is the section id.) -Now, XXX is defined as start_address_of_section / section_size. +Now, XXX is defined as (start_address_of_section / section_size) of the first +section contained in the memory block. The files 'phys_index' and +'end_phys_index' under each directory report the beginning and end section id's +for the memory block covered by the sysfs directory. It is expected that all +memory sections in this range are present and no memory holes exist in the +range. Currently there is no way to determine if there is a memory hole, but +the existence of one should not affect the hotplug capabilities of the memory +block. For example, assume 1GiB section size. A device for a memory starting at 0x100000000 is /sys/device/system/memory/memory4 (0x100000000 / 1Gib = 4) This device covers address range [0x100000000 ... 0x140000000) -Under each section, you can see 4 files. +Under each section, you can see 4 or 5 files, the end_phys_index file being +a recent addition and not present on older kernels. -/sys/devices/system/memory/memoryXXX/phys_index +/sys/devices/system/memory/memoryXXX/start_phys_index +/sys/devices/system/memory/memoryXXX/end_phys_index /sys/devices/system/memory/memoryXXX/phys_device /sys/devices/system/memory/memoryXXX/state /sys/devices/system/memory/memoryXXX/removable -'phys_index' : read-only and contains section id, same as XXX. -'state' : read-write - at read: contains online/offline state of memory. - at write: user can specify "online", "offline" command -'phys_device': read-only: designed to show the name of physical memory device. - This is not well implemented now. -'removable' : read-only: contains an integer value indicating - whether the memory section is removable or not - removable. A value of 1 indicates that the memory - section is removable and a value of 0 indicates that - it is not removable. +'phys_index' : read-only and contains section id of the first section + in the memory block, same as XXX. +'end_phys_index' : read-only and contains section id of the last section + in the memory block. +'state' : read-write + at read: contains online/offline state of memory. + at write: user can specify "online", "offline" command + which will be performed on al sections in the block. +'phys_device' : read-only: designed to show the name of physical memory + device. This is not well implemented now. +'removable' : read-only: contains an integer value indicating + whether the memory block is removable or not + removable. A value of 1 indicates that the memory + block is removable and a value of 0 indicates that + it is not removable. A memory block is removable only if + every section in the block is removable. NOTE: These directories/files appear after physical memory hotplug phase. |