Document/kexec: generalize crash hotplug description

Commit 79365026f869 ("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>

4 files changed, 15 insertions, 12 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-memory b/Documentation/ABI/testing/sysfs-devices-memory
index a95e0f17c35a..cec65827e602 100644
--- a/Documentation/ABI/testing/sysfs-devices-memory
+++ b/Documentation/ABI/testing/sysfs-devices-memory
@@ -115,6 +115,6 @@ What:		/sys/devices/system/memory/crash_hotplug
 Date:		Aug 2023
 Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
 Description:
-		(RO) indicates whether or not the kernel directly supports
-		modifying the crash elfcorehdr for memory hot un/plug and/or
-		on/offline changes.
+		(RO) indicates whether or not the kernel updates relevant kexec
+		segments on memory hot un/plug and/or on/offline events, avoiding the
+		need to reload kdump kernel.
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index de725ca3be82..206079d3bd5b 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -704,9 +704,9 @@ What:		/sys/devices/system/cpu/crash_hotplug
 Date:		Aug 2023
 Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
 Description:
-		(RO) indicates whether or not the kernel directly supports
-		modifying the crash elfcorehdr for CPU hot un/plug and/or
-		on/offline changes.
+		(RO) indicates whether or not the kernel updates relevant kexec
+		segments on memory hot un/plug and/or on/offline events, avoiding the
+		need to reload kdump kernel.
 
 What:		/sys/devices/system/cpu/enabled
 Date:		Nov 2022
diff --git a/Documentation/admin-guide/mm/memory-hotplug.rst b/Documentation/admin-guide/mm/memory-hotplug.rst
index 098f14d83e99..cb2c080f400c 100644
--- a/Documentation/admin-guide/mm/memory-hotplug.rst
+++ b/Documentation/admin-guide/mm/memory-hotplug.rst
@@ -294,8 +294,9 @@ The following files are currently defined:
 ``crash_hotplug``      read-only: when changes to the system memory map
 		       occur due to hot un/plug of memory, this file contains
 		       '1' if the kernel updates the kdump capture kernel memory
-		       map itself (via elfcorehdr), or '0' if userspace must update
-		       the kdump capture kernel memory map.
+		       map itself (via elfcorehdr and other relevant kexec
+		       segments), or '0' if userspace must update the kdump
+		       capture kernel memory map.
 
 		       Availability depends on the CONFIG_MEMORY_HOTPLUG kernel
 		       configuration option.
diff --git a/Documentation/core-api/cpu_hotplug.rst b/Documentation/core-api/cpu_hotplug.rst
index dcb0e379e5e8..a21dbf261be7 100644
--- a/Documentation/core-api/cpu_hotplug.rst
+++ b/Documentation/core-api/cpu_hotplug.rst
@@ -737,8 +737,9 @@ 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.
+updates the kdump capture kernel list of CPUs itself (via elfcorehdr and
+other relevant kexec segment), or '0' if userspace must update the kdump
+capture kernel list of CPUs.
 
 The availability depends on the CONFIG_HOTPLUG_CPU kernel configuration
 option.
@@ -750,8 +751,9 @@ 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.
+of the elfcorehdr (which contains the list of CPUs) and other relevant
+kexec segments, then the rule skips the unload-then-reload of the kdump
+capture kernel.
 
 Kernel Inline Documentations Reference
 ======================================