Investigated the bootstrap thread bring-up needed for Design A
(worker-offload). Finding: `rlct_clone_impl` requires a fully-built TCB
for the new thread, but bootstrap's freestanding redox_rt has no
Tcb::new / TLS allocator / thread shim (only initialize_freestanding's
single TCB). So Design A needs, as a prerequisite, a freestanding
thread-spawn helper in redox_rt (its own task) — open-coding TCB/TLS in
initnsmgr is not acceptable.
Revised ordering: keep Step 1 (Arc<Mutex> Send refactor, inert until A),
boot-validate on idle + commit; then prefer Design B (kernel O_NONBLOCK
on open + single-thread deferred, no bootstrap threads) as the first
functional step; Design A later once redox_rt grows the freestanding
thread helper. All still require an idle host to validate.
vasilito
e38a444303