Re: [PATCH 1/2] boot: android: Always use 8-byte aligned DT with libfdt

[Mattijs Korpershoek <mkorpershoek@kernel.org>]

On Thu, Nov 13, 2025 at 22:42, Marek Vasut <marek.vasut@mailbox.org> wrote:

> On 11/13/25 9:36 PM, Tom Rini wrote:
>
> Hello everyone,
>
>>>> Which is different from disagreeing with your specific feedback about
>>>> how we get there, to be clear.
>> 
>> And again, since your feedback to this patch was "Don't?", I'm saying we
>> need to. But the rest of your feedback was structural on moving towards
>> resolving it and so I assume Marek will respond.
>
> The "blast radius" are these patches, that's all that tripped the tests:
>
>   - boot: android: Always use 8-byte aligned DT with libfdt
>   - test/py: android: Point fdt command to aligned addresses
>   - test/py: Use aligned address for overlays in 'extension' test
>   - sandbox: Fix DT compiler address warnings in sandbox DTs
>   - sandbox: Fix DT compiler pin warnings in sandbox DTs
>   - boot: Assure FDT is always at 8-byte aligned address
>   - arm: qemu: Eliminate fdt_high and initrd_high misuse
>   - efi_loader: Assure fitImage from capsule is used from 8-byte aligned 
> address
>   - MIPS: Assure end of U-Boot is at 8-byte aligned offset
>
> Regarding last minute alignment, the problem with this android image 
> seems to be in the android image itself, which packs in badly aligned 
> FDT. We therefore have to copy it out and realign.

Yes, the Android tools do not handle alignment by default. This is
stated in the Android docs [1].

Also see [2] on how a boot.img is usually structured.

In any case, if DT spec mandates alignement, I think it's good to
enforce the spec in the code.

[1] https://source.android.com/docs/core/architecture/dto/partitions#cfg-create
[2] https://source.android.com/docs/core/architecture/dto

>
> -- 
> Best regards,
> Marek Vasut