Transfer List Checksum Correction and Impact on Bloblist

[Raymond Mao]

Hi Harrison,

On Fri, 26 Sept 2025 at 12:10, Harrison Mutai <harrison.mutai at arm.com> wrote:
>
> Hi all,
>
> We recently applied changes to the transfer list library [1] to correct
> the checksum calculation. Previously, we used a simple byte-sum
> approach. However, we later realized this contradicts the Firmware
> Handoff specification, which states:
>
> > The checksum is set to a value such that the XOR over every byte in the
> > {tl_base_pa, …, tl_base_pa + used_size - 1} address range is equal to 0.
>
> This discrepancy creates problems when interoperating with Bloblist.
> Should Bloblist’s checksum calculation be updated to follow the same
> XOR-based method?
>

Currently I am working on patches [1] and [2] to enable Firmware
Handoff in U-Boot CI.
It is pointing to TF-A v2.13.0 so actually the changes later that it
won't break anything at the moment.
Do you know the plan for the next TF-A 'non-RC' release? I think you
can send a patch to update the checksum when the 'non-RC' release is
done and then I can let CI point to the new release.

[1] https://lore.kernel.org/u-boot/20250916161426.32259-1-raymond.mao@linaro.org/
[2] https://lore.kernel.org/u-boot/20250916161230.32140-1-raymond.mao@linaro.org/

Regards,
Raymond

> [1]
> https://review.trustedfirmware.org/c/shared/transfer-list-library/+/42548
>
> All the best,
> Harrison