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

[Coiby Xu]

On Mon, Mar 30, 2026 at 06:44:15AM -0500, Rob Herring wrote:
> On Wed, Feb 25, 2026 at 12:04 AM Coiby Xu <coxu@xxxxxxxxxx> 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/20250502011246.99238-1-coxu@xxxxxxxxxx/
> > [2] https://github.com/devicetree-org/dt-schema/pull/181
> >
> > Cc: Arnaud Lefebvre <arnaud.lefebvre@xxxxxxxxxxxxxxxx>
> > Cc: Baoquan he <bhe@xxxxxxxxxx>
> > Cc: Dave Young <dyoung@xxxxxxxxxx>
> > Cc: Kairui Song <ryncsn@xxxxxxxxx>
> > Cc: Pingfan Liu <kernelfans@xxxxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Cc: Thomas Staudt <tstaudt@xxxxxxxxxx>
> > Cc: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
> > Cc: Will Deacon <will@xxxxxxxxxx>
> > Cc: Christophe Leroy (CS GROUP) <chleroy@xxxxxxxxxx>
> > Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
> > ---
> >  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) <robh@xxxxxxxxxx>

Hi Rob,

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

--
Best regards,
Coiby