Commit fb5c3644 authored by Sourabh Jain's avatar Sourabh Jain Committed by Andrew Morton
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Documentation/ABI: new kexec and kdump sysfs interface 

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/kexec/crash_elfcorehdr_size
- /sys/kernel/kexec/crash_cma_ranges

Link: https://lkml.kernel.org/r/20251118114507.1769455-4-sourabhjain@linux.ibm.com


Signed-off-by: default avatarSourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: default avatarBaoquan He <bhe@redhat.com>
Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh J Salgaonkar <mahesh@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5c991b6d

Documentation/ABI/testing/sysfs-kernel-kexec-kdump

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What:		/sys/kernel/kexec/*

Date:		Nov 2025

Contact:	kexec@lists.infradead.org

Description:

		The /sys/kernel/kexec/* directory contains sysfs files

		that provide information about the configuration status

		of kexec and kdump.



What:		/sys/kernel/kexec/loaded

Date:		Nov 2025

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:		Nov 2025

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:		Nov 2025

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/kexec/crash_elfcorehdr_size

Date:		Nov 2025

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



What:		/sys/kernel/kexec/crash_cma_ranges

Date:		Nov 2025

Contact:	kexec@lists.infradead.org

Description:	read only

		Provides information about the memory ranges reserved from

		the Contiguous Memory Allocator (CMA) area that are allocated

		to the crash (kdump) kernel. It lists the start and end physical

		addresses of CMA regions assigned for crashkernel use.

User:		kdump service