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c91c6062d6
Commit 79365026f8 ("crash: add a new kexec flag for hotplug support")
generalizes the crash hotplug support to allow architectures to update
multiple kexec segments on CPU/Memory hotplug and not just elfcorehdr.
Therefore, update the relevant kernel documentation to reflect the same.
No functional change.
Link: https://lkml.kernel.org/r/20240812041651.703156-1-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Reviewed-by: Petr Tesarik <ptesarik@suse.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Petr Tesarik <petr@tesarici.cz>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
121 lines
4.6 KiB
Plaintext
121 lines
4.6 KiB
Plaintext
What: /sys/devices/system/memory
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Date: June 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The /sys/devices/system/memory contains a snapshot of the
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internal state of the kernel memory blocks. Files could be
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added or removed dynamically to represent hot-add/remove
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operations.
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Users: hotplug memory add/remove tools
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http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
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What: /sys/devices/system/memory/memoryX/removable
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Date: June 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/removable is a
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legacy interface used to indicated whether a memory block is
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likely to be offlineable or not. Newer kernel versions return
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"1" if and only if the kernel supports memory offlining.
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Users: hotplug memory remove tools
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http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
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lsmem/chmem part of util-linux
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What: /sys/devices/system/memory/memoryX/phys_device
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Date: September 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/phys_device
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is read-only; it is a legacy interface only ever used on s390x
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to expose the covered storage increment.
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Users: Legacy s390-tools lsmem/chmem
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What: /sys/devices/system/memory/memoryX/phys_index
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Date: September 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/phys_index
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is read-only and contains the section ID in hexadecimal
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which is equivalent to decimal X contained in the
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memory section directory name.
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What: /sys/devices/system/memory/memoryX/state
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Date: September 2008
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Contact: Badari Pulavarty <pbadari@us.ibm.com>
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Description:
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The file /sys/devices/system/memory/memoryX/state
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is read-write. When read, it returns the online/offline
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state of the memory block. When written, root can toggle
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the online/offline state of a memory block using the following
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commands::
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# echo online > /sys/devices/system/memory/memoryX/state
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# echo offline > /sys/devices/system/memory/memoryX/state
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On newer kernel versions, advanced states can be specified
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when onlining to select a target zone: "online_movable"
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selects the movable zone. "online_kernel" selects the
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applicable kernel zone (DMA, DMA32, or Normal). However,
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after successfully setting one of the advanced states,
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reading the file will return "online"; the zone information
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can be obtained via "valid_zones" instead.
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While onlining is unlikely to fail, there are no guarantees
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that offlining will succeed. Offlining is more likely to
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succeed if "valid_zones" indicates "Movable".
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Users: hotplug memory remove tools
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http://www.ibm.com/developerworks/wikis/display/LinuxP/powerpc-utils
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What: /sys/devices/system/memory/memoryX/valid_zones
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Date: July 2014
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Contact: Zhang Zhen <zhenzhang.zhang@huawei.com>
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Description:
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The file /sys/devices/system/memory/memoryX/valid_zones is
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read-only.
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For online memory blocks, it returns in which zone memory
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provided by a memory block is managed. If multiple zones
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apply (not applicable for hotplugged memory), "None" is returned
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and the memory block cannot be offlined.
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For offline memory blocks, it returns by which zone memory
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provided by a memory block can be managed when onlining.
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The first returned zone ("default") will be used when setting
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the state of an offline memory block to "online". Only one of
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the kernel zones (DMA, DMA32, Normal) is applicable for a single
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memory block.
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What: /sys/devices/system/memoryX/nodeY
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Date: October 2009
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Contact: Linux Memory Management list <linux-mm@kvack.org>
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Description:
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When CONFIG_NUMA is enabled, a symbolic link that
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points to the corresponding NUMA node directory.
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For example, the following symbolic link is created for
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memory section 9 on node0:
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/sys/devices/system/memory/memory9/node0 -> ../../node/node0
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What: /sys/devices/system/node/nodeX/memoryY
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Date: September 2008
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Contact: Gary Hade <garyhade@us.ibm.com>
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Description:
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When CONFIG_NUMA is enabled
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/sys/devices/system/node/nodeX/memoryY is a symbolic link that
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points to the corresponding /sys/devices/system/memory/memoryY
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memory section directory. For example, the following symbolic
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link is created for memory section 9 on node0.
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/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
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What: /sys/devices/system/memory/crash_hotplug
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Date: Aug 2023
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Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
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Description:
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(RO) indicates whether or not the kernel updates relevant kexec
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segments on memory hot un/plug and/or on/offline events, avoiding the
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need to reload kdump kernel.
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