[PATCH 1/2] Documentation/ABI: add kexec and kdump sysfs interface

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Add an ABI document for following kexec and kdump sysfs interface:
- /sys/kernel/kexec_loaded
- /sys/kernel/kexec_crash_loaded
- /sys/kernel/kexec_crash_size
- /sys/kernel/crash_elfcorehdr_size

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan he <bhe@redhat.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: kexec@lists.infradead.org
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 .../ABI/testing/sysfs-kernel-kexec-kdump      | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-kexec-kdump

diff --git a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump
new file mode 100644
index 000000000000..96b24565b68e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump
@@ -0,0 +1,43 @@
+What:		/sys/kernel/kexec_loaded
+Date:		Jun 2006
+Contact:	kexec@lists.infradead.org
+Description:	read only
+		Indicates whether a new kernel image has been loaded
+		into memory using the kexec system call. It shows 1 if
+		a kexec image is present and ready to boot, or 0 if none
+		is loaded.
+User:		kexec tools, kdump service
+
+What:		/sys/kernel/kexec_crash_loaded
+Date:		Jun 2006
+Contact:	kexec@lists.infradead.org
+Description:	read only
+		Indicates whether a crash (kdump) kernel is currently
+		loaded into memory. It shows 1 if a crash kernel has been
+		successfully loaded for panic handling, or 0 if no crash
+		kernel is present.
+User:		Kexec tools, Kdump service
+
+What:		/sys/kernel/kexec_crash_size
+Date:		Dec 2009
+Contact:	kexec@lists.infradead.org
+Description:	read/write
+		Shows the amount of memory reserved for loading the crash
+		(kdump) kernel. It reports the size, in bytes, of the
+		crash kernel area defined by the crashkernel= parameter.
+		This interface also allows reducing the crashkernel
+		reservation by writing a smaller value, and the reclaimed
+		space is added back to the system RAM.
+User:		Kdump service
+
+What:		/sys/kernel/crash_elfcorehdr_size
+Date:		Aug 2023
+Contact:	kexec@lists.infradead.org
+Description:	read only
+		Indicates the preferred size of the memory buffer for the
+		ELF core header used by the crash (kdump) kernel. It defines
+		how much space is needed to hold metadata about the crashed
+		system, including CPU and memory information. This information
+		is used by the user space utility kexec to support updating the
+		in-kernel kdump image during hotplug operations.
+User:		Kexec tools
-- 
2.51.0