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linux/Documentation/ABI/obsolete/sysfs-kernel-kexec-kdump
Sourabh Jain 5c991b6d9b Documentation/ABI: mark old kexec sysfs deprecated
The previous commit ("kexec: move sysfs entries to /sys/kernel/kexec")
moved all existing kexec sysfs entries to a new location. The ABI
document is updated to include a note about the deprecation of the old
kexec sysfs entries.

The following kexec sysfs entries are deprecated:
- /sys/kernel/kexec_loaded
- /sys/kernel/kexec_crash_loaded
- /sys/kernel/kexec_crash_size
- /sys/kernel/crash_elfcorehdr_size
- /sys/kernel/kexec_crash_cma_ranges

Link: https://lkml.kernel.org/r/20251118114507.1769455-3-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan 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: Andrew Morton <akpm@linux-foundation.org>
2025-11-27 14:24:43 -08:00

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NOTE: all the ABIs listed in this file are deprecated and will be removed after 2028.
Here are the alternative ABIs:
+------------------------------------+-----------------------------------------+
| Deprecated | Alternative |
+------------------------------------+-----------------------------------------+
| /sys/kernel/kexec_loaded | /sys/kernel/kexec/loaded |
+------------------------------------+-----------------------------------------+
| /sys/kernel/kexec_crash_loaded | /sys/kernel/kexec/crash_loaded |
+------------------------------------+-----------------------------------------+
| /sys/kernel/kexec_crash_size | /sys/kernel/kexec/crash_size |
+------------------------------------+-----------------------------------------+
| /sys/kernel/crash_elfcorehdr_size | /sys/kernel/kexec/crash_elfcorehdr_size |
+------------------------------------+-----------------------------------------+
| /sys/kernel/kexec_crash_cma_ranges | /sys/kernel/kexec/crash_cma_ranges |
+------------------------------------+-----------------------------------------+
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
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