linux-kernel - Re: [PATCH 0/2] Export kdump crashkernel CMA ranges

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Message-ID: <a81bf9c0-f8c8-49f9-965d-26f704a73517@linux.ibm.com>
Date: Wed, 5 Nov 2025 09:03:43 +0530
From: Sourabh Jain <sourabhjain@...ux.ibm.com>
To: Baoquan he <bhe@...hat.com>
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
        Jiri Bohac <jbohac@...e.cz>, Shivang Upadhyay <shivangu@...ux.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org, kexec@...ts.infradead.org
Subject: Re: [PATCH 0/2] Export kdump crashkernel CMA ranges



On 05/11/25 08:45, Baoquan he wrote:
> On 11/03/25 at 09:28am, Sourabh Jain wrote:
>> /sys/kernel/kexec_crash_cma_ranges to export all CMA regions reserved
>> for the crashkernel to user-space. This enables user-space tools
>> configuring kdump to determine the amount of memory reserved for the
>> crashkernel. When CMA is used for crashkernel allocation, tools can use
>> this information to warn users that attempting to capture user pages
>> while CMA reservation is active may lead to unreliable or incomplete
>> dump capture.
>>
>> While adding documentation for the new sysfs interface, I realized that
>> there was no ABI document for the existing kexec and kdump sysfs
>> interfaces, so I added one.
>>
>> The first patch adds the ABI documentation for the existing kexec and
>> kdump sysfs interfaces, and the second patch adds the
>> /sys/kernel/kexec_crash_cma_ranges sysfs interface along with its
>> corresponding ABI documentation.
>>
>> *Seeking opinions*
>> There are already four kexec/kdump sysfs entries under /sys/kernel/,
>> and this patch series adds one more. Should we consider moving them to
>> a separate directory, such as /sys/kernel/kexec, to avoid polluting
>> /sys/kernel/? For backward compatibility, we can create symlinks at
>> the old locations for sometime and remove them in the future.
> That sounds a good idea, will you do it in v2? Because otherwise the
> kexec_crash_cma_ranges need be moved too.

Yes I will include it in v2.

Thanks,
Sourabh Jain