Subject: Re: [PATCH v5 3/3] arm64,ppc64le/kdump: pass dm-crypt keys to kdump kernel

From: Coiby Xu <[email-masked]>
Date: Thu, 2 Apr 2026 09:44:21 +0800

On Mon, Mar 30, 2026 at 06:44:15AM -0500, Rob Herring wrote:
>On Wed, Feb 25, 2026 at 12:04 AM Coiby Xu <[email-masked]> wrote:
>>
>> CONFIG_CRASH_DM_CRYPT has been introduced to support LUKS-encrypted
>> device dump target by addressing two challenges [1],
>>  - Kdump kernel may not be able to decrypt the LUKS partition. For some
>>    machines, a system administrator may not have a chance to enter the
>>    password to decrypt the device in kdump initramfs after the 1st kernel
>>    crashes
>>
>>  - LUKS2 by default use the memory-hard Argon2 key derivation function
>>    which is quite memory-consuming compared to the limited memory reserved
>>    for kdump.
>>
>> To also enable this feature for ARM64 and PowerPC, the missing piece is
>> to let the kdump kernel know where to find the dm-crypt keys which are
>> randomly stored in memory reserved for kdump. Introduce a new device
>> tree property dmcryptkeys [2] as similar to elfcorehdr to pass the
>> memory address of the stored info of dm-crypt keys to the kdump kernel.
>> Since this property is only needed by the kdump kernel, it won't be
>> exposed to user space.
>>
>> [1] https://lore.kernel.org/all/[email-masked]/
>> [2] https://github.com/devicetree-org/dt-schema/pull/181
>>
>> Cc: Arnaud Lefebvre <[email-masked]>
>> Cc: Baoquan he <[email-masked]>
>> Cc: Dave Young <[email-masked]>
>> Cc: Kairui Song <[email-masked]>
>> Cc: Pingfan Liu <[email-masked]>
>> Cc: Andrew Morton <[email-masked]>
>> Cc: Krzysztof Kozlowski <[email-masked]>
>> Cc: Rob Herring <[email-masked]>
>> Cc: Thomas Staudt <[email-masked]>
>> Cc: Sourabh Jain <[email-masked]>
>> Cc: Will Deacon <[email-masked]>
>> Cc: Christophe Leroy (CS GROUP) <[email-masked]>
>> Signed-off-by: Coiby Xu <[email-masked]>
>> ---
>>  arch/arm64/kernel/machine_kexec_file.c |  4 ++++
>>  arch/powerpc/kexec/elf_64.c            |  4 ++++
>>  drivers/of/fdt.c                       | 21 +++++++++++++++++++++
>>  drivers/of/kexec.c                     | 19 +++++++++++++++++++
>>  4 files changed, 48 insertions(+)
>
>Acked-by: Rob Herring (Arm) <[email-masked]>

Hi Rob,

Thanks for acknowledging this device tree patch and also merging the
dt-schema PR!

-- 
Best regards,
Coiby