1What: /sys/devices/system/memory 2Date: June 2008 3Contact: Badari Pulavarty <pbadari@us.ibm.com> 4Description: 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. 9Users: hotplug memory add/remove tools 10 http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils 11 12What: /sys/devices/system/memory/memoryX/removable 13Date: June 2008 14Contact: Badari Pulavarty <pbadari@us.ibm.com> 15Description: 16 The file /sys/devices/system/memory/memoryX/removable is a 17 legacy interface used to indicated whether a memory block is 18 likely to be offlineable or not. Newer kernel versions return 19 "1" if and only if the kernel supports memory offlining. 20Users: hotplug memory remove tools 21 http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils 22 lsmem/chmem part of util-linux 23 24What: /sys/devices/system/memory/memoryX/phys_device 25Date: September 2008 26Contact: Badari Pulavarty <pbadari@us.ibm.com> 27Description: 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. 31Users: Legacy s390-tools lsmem/chmem 32 33What: /sys/devices/system/memory/memoryX/phys_index 34Date: September 2008 35Contact: Badari Pulavarty <pbadari@us.ibm.com> 36Description: 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 42What: /sys/devices/system/memory/memoryX/state 43Date: September 2008 44Contact: Badari Pulavarty <pbadari@us.ibm.com> 45Description: 46 The file /sys/devices/system/memory/memoryX/state 47 is read-write. When read, it returns the online/offline 48 state of the memory block. When written, root can toggle 49 the online/offline state of a memory block using the following 50 commands:: 51 52 # echo online > /sys/devices/system/memory/memoryX/state 53 # echo offline > /sys/devices/system/memory/memoryX/state 54 55 On newer kernel versions, advanced states can be specified 56 when onlining to select a target zone: "online_movable" 57 selects the movable zone. "online_kernel" selects the 58 applicable kernel zone (DMA, DMA32, or Normal). However, 59 after successfully setting one of the advanced states, 60 reading the file will return "online"; the zone information 61 can be obtained via "valid_zones" instead. 62 63 While onlining is unlikely to fail, there are no guarantees 64 that offlining will succeed. Offlining is more likely to 65 succeed if "valid_zones" indicates "Movable". 66Users: hotplug memory remove tools 67 http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils 68 69 70What: /sys/devices/system/memory/memoryX/valid_zones 71Date: July 2014 72Contact: Zhang Zhen <zhenzhang.zhang@huawei.com> 73Description: 74 The file /sys/devices/system/memory/memoryX/valid_zones is 75 read-only. 76 77 For online memory blocks, it returns in which zone memory 78 provided by a memory block is managed. If multiple zones 79 apply (not applicable for hotplugged memory), "None" is returned 80 and the memory block cannot be offlined. 81 82 For offline memory blocks, it returns by which zone memory 83 provided by a memory block can be managed when onlining. 84 The first returned zone ("default") will be used when setting 85 the state of an offline memory block to "online". Only one of 86 the kernel zones (DMA, DMA32, Normal) is applicable for a single 87 memory block. 88 89What: /sys/devices/system/memoryX/nodeY 90Date: October 2009 91Contact: Linux Memory Management list <linux-mm@kvack.org> 92Description: 93 When CONFIG_NUMA is enabled, a symbolic link that 94 points to the corresponding NUMA node directory. 95 96 For example, the following symbolic link is created for 97 memory section 9 on node0: 98 99 /sys/devices/system/memory/memory9/node0 -> ../../node/node0 100 101 102What: /sys/devices/system/node/nodeX/memoryY 103Date: September 2008 104Contact: Gary Hade <garyhade@us.ibm.com> 105Description: 106 When CONFIG_NUMA is enabled 107 /sys/devices/system/node/nodeX/memoryY is a symbolic link that 108 points to the corresponding /sys/devices/system/memory/memoryY 109 memory section directory. For example, the following symbolic 110 link is created for memory section 9 on node0. 111 112 /sys/devices/system/node/node0/memory9 -> ../../memory/memory9 113