Just to clarify: are you using "bloblist" as a general term for the concept of a simple linked list of tagged data blobs, or to refer specifically to the U-Boot implementation with that name? The existing TF-A implementation (bl_aux_params) is basically identical in concept to the U-Boot bloblist, but not binary compatible. Are we talking about just keeping that, or throwing it away in order to reimplement the exact structure U-Boot is using? (I would prefer to keep the bl_aux_params as they are to avoid disrupting existing uses, of course. Making backwards-incompatible changes to an interface that passes across multiple repos and firmware components is always a big pain.)