On Mon, 17 Nov 2025 09:49:05 +0530 Sourabh Jain [off-list ref] wrote:

Add a sysfs entry /sys/kernel/kexec/crash_cma_ranges to expose all
CMA crashkernel ranges.

This allows userspace tools configuring kdump to determine how much
memory is reserved for crashkernel. If CMA is used, tools can warn
users when attempting to capture user pages with CMA reservation.

The new sysfs hold the CMA ranges in below format:

cat /sys/kernel/kexec/crash_cma_ranges
100000000-10c7fffff

There are already four kexec and kdump sysfs entries under /sys/kernel.
Adding more entries there would clutter the directory. To avoid this,
the new crash_cma_ranges sysfs entry is placed in a new kexec node under
/sys/kernel/.

I suggest not creating /sys/kernel/kexec in this patch.

Moving everything into a new /sys/kernel/kexec is a separate patchset
and a separate concept and it might never be merged - it changes ABI!

So let's put crash_cma_ranges in /sys/kernel and move it to
/sys/kernel/kexec within the other patchset.