Re: [PATCH v4 0/5] kexec: reorganize sysfs interface and add new kexec sysfs

[Sourabh Jain]

On 15/11/25 04:55, Andrew Morton wrote:
> On Fri, 14 Nov 2025 10:44:59 +0530 Sourabh Jain <sourabhjain@xxxxxxxxxxxxx> wrote:
>
> > All existing kexec and kdump sysfs entries are moved to a new location,
> > /sys/kernel/kexec, to keep /sys/kernel/ clean and better organized.
> > Symlinks are created at the old locations for backward compatibility and
> > can be removed in the future [02/05].
> >
> > While doing this cleanup, missing ABI documentation for the old sysfs
> > interfaces is added, and those entries are marked as deprecated
> > [01/05 and 03/05]. New ABI documentation is also added for the
> > reorganized interfaces. [04/05]
> >
> > Along with this reorganization, a new sysfs file,
> > /sys/kernel/kexec/crash_cma_ranges, is introduced to export crashkernel
> > CMA reservation details to user space [05/05]. This helps tools
> > determine the total crashkernel reserved memory and warn users that
> > capturing user pages while CMA is reserved may cause incomplete or
> > unreliable dumps.
> Patchset does three unrelated things in remarkably random order.
>
> 1: Document existing stuff
>
> 	Great, thanks, in it goes.
>
> 2: export crashkernel CMA reservation to userspace
>
> 	Well, OK, probably reasonable, didn't look closely.
>
> 3: Alter longstanding userspace ABI with deprecation plan
>
> 	Whoa, tricky, needs careful consideration.
>
>
> So can we please prepare and consider this material in three separate
> patchsets?  In the above order, I suggest.

Yeah sure.

The question here is where to add the new CMA reservation sysfs.
Should I place it under /sys/kernel/ or create /sys/kernel/kexec and
add it there?

Since I am proposing that all kexec sysfs entries move to the new
location /sys/kernel/kexec, I am going to add the CMA reservation
sysfs under /sys/kernel/kexec to avoid creating a symlink for this
entry later in my third patch series.

- Sourabh