Re: [PATCH v2] arm64/kdump: pass dm-crypt keys to kdump kernel

[Coiby Xu]

On Tue, Jan 06, 2026 at 09:05:49AM +0100, Krzysztof Kozlowski wrote:
> On Tue, Jan 06, 2026 at 02:22:30PM +0800, Coiby Xu 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, we only need to add 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.
> >
> > [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>
> > Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
> > ---
> > v2
> > - Krzysztof
> >   - Use imperative mood for commit message
> >   - Add dt-schema ABI Documentation
> > - Don't print dm-crypt keys address via pr_debug
>
> Your changelog should explicitly document that this has external
> dependency on dtschema pull request, so that maintainers know that.

Thanks for the lightning-fast reply!

And thanks for the reminder! I didn't know the dtschema pull request is
regarded as a dependency. Currently, I only add the dtschema pull
request URL to the commit message. I'll also include it in the
changelog.

> Also, in the future:
> Do not attach (thread) your patchsets to some other threads (unrelated
> or older versions). This buries them deep in the mailbox and might
> interfere with applying entire sets. See also:
> https://elixir.bootlin.com/linux/v6.16-rc2/source/Documentation/process/submitting-patches.rst#L830

Thanks for pointing me to the above documentation! I thought adding
In-Reply-To to the V1 patch can provide better context since it's a
single patch. It seems this is not true for Devicetree. Is it because of
the documentation change thus we should treat it more like a multi-patch
series?

> Best regards,
> Krzysztof

--
Best regards,
Coiby