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author | Linus Torvalds <torvalds@linux-foundation.org> | 2023-08-30 00:53:51 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-08-30 00:53:51 +0300 |
commit | d68b4b6f307d155475cce541f2aee938032ed22e (patch) | |
tree | c2a6487ac8b1bce963b5b352b42e461a6fa8da15 /Documentation/core-api/cpu_hotplug.rst | |
parent | b96a3e9142fdf346b05b20e867b4f0dfca119e96 (diff) | |
parent | dce8f8ed1de1d9d6d27c5ccd202ce4ec163b100c (diff) | |
download | linux-d68b4b6f307d155475cce541f2aee938032ed22e.tar.xz |
Merge tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- An extensive rework of kexec and crash Kconfig from Eric DeVolder
("refactor Kconfig to consolidate KEXEC and CRASH options")
- kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
couple of macros to args.h")
- gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
commands")
- vsprintf inclusion rationalization from Andy Shevchenko
("lib/vsprintf: Rework header inclusions")
- Switch the handling of kdump from a udev scheme to in-kernel
handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory
hot un/plug")
- Many singleton patches to various parts of the tree
* tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits)
document while_each_thread(), change first_tid() to use for_each_thread()
drivers/char/mem.c: shrink character device's devlist[] array
x86/crash: optimize CPU changes
crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()
crash: hotplug support for kexec_load()
x86/crash: add x86 crash hotplug support
crash: memory and CPU hotplug sysfs attributes
kexec: exclude elfcorehdr from the segment digest
crash: add generic infrastructure for crash hotplug support
crash: move a few code bits to setup support of crash hotplug
kstrtox: consistently use _tolower()
kill do_each_thread()
nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse
scripts/bloat-o-meter: count weak symbol sizes
treewide: drop CONFIG_EMBEDDED
lockdep: fix static memory detection even more
lib/vsprintf: declare no_hash_pointers in sprintf.h
lib/vsprintf: split out sprintf() and friends
kernel/fork: stop playing lockless games for exe_file replacement
adfs: delete unused "union adfs_dirtail" definition
...
Diffstat (limited to 'Documentation/core-api/cpu_hotplug.rst')
-rw-r--r-- | Documentation/core-api/cpu_hotplug.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/core-api/cpu_hotplug.rst b/Documentation/core-api/cpu_hotplug.rst index b9ae591d0b18..9511e405aabd 100644 --- a/Documentation/core-api/cpu_hotplug.rst +++ b/Documentation/core-api/cpu_hotplug.rst @@ -741,6 +741,24 @@ will receive all events. A script like:: can process the event further. +When changes to the CPUs in the system occur, the sysfs file +/sys/devices/system/cpu/crash_hotplug contains '1' if the kernel +updates the kdump capture kernel list of CPUs itself (via elfcorehdr), +or '0' if userspace must update the kdump capture kernel list of CPUs. + +The availability depends on the CONFIG_HOTPLUG_CPU kernel configuration +option. + +To skip userspace processing of CPU hot un/plug events for kdump +(i.e. the unload-then-reload to obtain a current list of CPUs), this sysfs +file can be used in a udev rule as follows: + + SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end" + +For a CPU hot un/plug event, if the architecture supports kernel updates +of the elfcorehdr (which contains the list of CPUs), then the rule skips +the unload-then-reload of the kdump capture kernel. + Kernel Inline Documentations Reference ====================================== |