merged_digest answered "no log" before it looked at the layout, so a bare
v3/v4 image fell through to the packed walk — which starts at the v2 header
length and reads index entries as record frames. A bare addressed image with
no log beside it therefore read as a one-record store with an empty value.
An addressed image is a complete store on its own: its index holds every
record and says where each one is, so a log is an addition rather than a
requirement. A packed image is not, which is why "no log" still means what it
meant for v1/v2.
Found by verify-image-read the moment userspace started writing v4: while
every userspace image was v2 the fallback happened to be the right walk. The
kernel's own v4 images always had a log header beside them, so no other gate
could have caught it.
surface-camera-build
72e72fe7a8