+Illias to the thread
On 01/10/2025 16:54, Raymond Mao wrote:
Hi Harrison,
On Tue, 30 Sept 2025 at 06:54, Harrison Mutai <[email protected]> wrote:
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].
There is a question: How did you pass the OP-TEE CI test without U-Boot changes?
There is a CI check QEMUv8_check2 in OP-TEE that builds with Firmware
Handoff enabled, but the manifest is pointing to U-Boot v2025.07-rc1.
So I think unless you have merged the updated checksum to U-Boot and
updated the OP-TEE manifest with that commit-id, otherwise
QEMUv8_check2 will still fail due to the mismatching checksum
algorithm.
Ah yes that's a good catch. I've held that patch while we discuss things
here and in the handoff spec forum.
Regards,
Raymond
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
