A node writing to a node that was stuck, and was then killed, stayed
blocked for ever: killing a stuck node could cost its neighbours. And on
the hosted and bare-metal products a write to an empty port, 5 7 PORT!,
ended the program with "the node stopped".
Now a node that can take an error, blocked writing to or reading from one
port that nothing is wired to -- nothing ever was, or what was there has
been killed or the wire cut -- has error 18, No one on that port, raised
on it and goes on. A bare node waits as on the fabric; so does a node
whose neighbour is asleep, and one reading "any port".
test_host_unit.c: Hera kills node 14 while node 12 is blocked writing to
it. It failed first: 12 stayed blocked. test_fabric.c: a bare node still
waits. hosted-check types 5 7 PORT! and goes on; it failed first too.
make -C v4 test, sanitize and hosted-check pass; amd64, aarch64 and
riscv64 boot, POST 538 of 538, dict_hash 0x5f0a949a6fc8ef2b on all six:
logs/20261007-121743, -122008, -122337.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
