Comment 1 for bug 1921948

I believe that you're correct, and that I mis-read the MTE specification.

I believed that exactly one mte tag check was made for any single memory
access. But I missed that unaligned accesses are as-if a sequence of byte
accesses -- in the Arm ARM, see aarch64/functions/memory/Mem[].

I'm still trying to verify this via the Arm FVP, but so far I've not
found the right incantation of parameters to properly enable MTE.
(I can enable the instructions, but a simple stg/ldg test suggests
that there is no tag storage enabled -- all tags read as 0.)