Re: Transfer List Checksum Correction and Impact on Bloblist

[Tom Rini]

On Fri, Sep 26, 2025 at 05:09:53PM +0100, Harrison Mutai 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?
> 
> [1]
> https://review.trustedfirmware.org/c/shared/transfer-list-library/+/42548

Erm, since this has been out in the wild so to speak, we can't just
change the algorithm without bumping some cardinal. Or are there yet
other implementations that were doing what the spec said?

-- 
Tom

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