On 29/09/2025 19:11, Tom Rini wrote:
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?
Raymond; Thanks for setting up the handoff tests. The next release for
TF-A is planned for mid-November [1].
We’ve run into an issue where TF-A requires specific tags from the
transfer list library, but we can’t consume them due to the recent
checksum changes.
Tom; As it stands, ours is the only implementation currently using the
updated checksum algorithm. There are two other consumers - OP-TEE and
EDK2. OP-TEE already has a patch in upstream review to move to the new
algorithm [2].
I’ve also reached out to the author of the EDK2 implementation to make
them aware of the change.
[1]
https://trustedfirmware-a.readthedocs.io/en/latest/about/release-information.html
[2] https://github.com/OP-TEE/optee_os/pull/7531
