Documentation/ABI/testing/sysfs-devices-memory

   1 What:           /sys/devices/system/memory
   2 Date:           June 2008
   3 Contact:        Badari Pulavarty <pbadari@us.ibm.com>
   4 Description:
   5                 The /sys/devices/system/memory contains a snapshot of the
   6                 internal state of the kernel memory blocks. Files could be
   7                 added or removed dynamically to represent hot-add/remove
   8                 operations.
   9 Users:          hotplug memory add/remove tools
  10                 http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
  11
  12 What:           /sys/devices/system/memory/memoryX/removable
  13 Date:           June 2008
  14 Contact:        Badari Pulavarty <pbadari@us.ibm.com>
  15 Description:
  16                 The file /sys/devices/system/memory/memoryX/removable
  17                 indicates whether this memory block is removable or not.
  18                 This is useful for a user-level agent to determine
  19                 identify removable sections of the memory before attempting
  20                 potentially expensive hot-remove memory operation
  21 Users:          hotplug memory remove tools
  22                 http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
  23
  24 What:           /sys/devices/system/memory/memoryX/phys_device
  25 Date:           September 2008
  26 Contact:        Badari Pulavarty <pbadari@us.ibm.com>
  27 Description:
  28                 The file /sys/devices/system/memory/memoryX/phys_device
  29                 is read-only;  it is a legacy interface only ever used on s390x
  30                 to expose the covered storage increment.
  31 Users:          Legacy s390-tools lsmem/chmem
  32
  33 What:           /sys/devices/system/memory/memoryX/phys_index
  34 Date:           September 2008
  35 Contact:        Badari Pulavarty <pbadari@us.ibm.com>
  36 Description:
  37                 The file /sys/devices/system/memory/memoryX/phys_index
  38                 is read-only and contains the section ID in hexadecimal
  39                 which is equivalent to decimal X contained in the
  40                 memory section directory name.
  41
  42 What:           /sys/devices/system/memory/memoryX/state
  43 Date:           September 2008
  44 Contact:        Badari Pulavarty <pbadari@us.ibm.com>
  45 Description:
  46                 The file /sys/devices/system/memory/memoryX/state
  47                 is read-write.  When read, its contents show the
  48                 online/offline state of the memory section.  When written,
  49                 root can toggle the the online/offline state of a removable
  50                 memory section (see removable file description above)
  51                 using the following commands::
  52
  53                   # echo online > /sys/devices/system/memory/memoryX/state
  54                   # echo offline > /sys/devices/system/memory/memoryX/state
  55
  56                 For example, if /sys/devices/system/memory/memory22/removable
  57                 contains a value of 1 and
  58                 /sys/devices/system/memory/memory22/state contains the
  59                 string "online" the following command can be executed by
  60                 by root to offline that section::
  61
  62                   # echo offline > /sys/devices/system/memory/memory22/state
  63
  64 Users:          hotplug memory remove tools
  65                 http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
  66
  67
  68 What:           /sys/devices/system/memory/memoryX/valid_zones
  69 Date:           July 2014
  70 Contact:        Zhang Zhen <zhenzhang.zhang@huawei.com>
  71 Description:
  72                 The file /sys/devices/system/memory/memoryX/valid_zones is
  73                 read-only and is designed to show which zone this memory
  74                 block can be onlined to.
  75
  76 What:           /sys/devices/system/memoryX/nodeY
  77 Date:           October 2009
  78 Contact:        Linux Memory Management list <linux-mm@kvack.org>
  79 Description:
  80                 When CONFIG_NUMA is enabled, a symbolic link that
  81                 points to the corresponding NUMA node directory.
  82
  83                 For example, the following symbolic link is created for
  84                 memory section 9 on node0:
  85
  86                 /sys/devices/system/memory/memory9/node0 -> ../../node/node0
  87
  88
  89 What:           /sys/devices/system/node/nodeX/memoryY
  90 Date:           September 2008
  91 Contact:        Gary Hade <garyhade@us.ibm.com>
  92 Description:
  93                 When CONFIG_NUMA is enabled
  94                 /sys/devices/system/node/nodeX/memoryY is a symbolic link that
  95                 points to the corresponding /sys/devices/system/memory/memoryY
  96                 memory section directory.  For example, the following symbolic
  97                 link is created for memory section 9 on node0.
  98
  99                 /sys/devices/system/node/node0/memory9 -> ../../memory/memory9