Adds doc comments above lwarx/ldarx/stwcx./stdcx. clarifying that the
legacy per-ctx reservation path is only correct in strict lockstep
(single host thread); under --parallel the M3 scheduler must enable
the cross-thread ReservationTable before spawning a second host thread.
A debug_assert fires in the legacy stwcx./stdcx. branch if a
non-primary HW slot (hw_id != 0) takes that path — surfacing
ReservationTable-disabled misconfiguration early in debug builds.
Note: the primary slot (hw_id==0) racing other parallel slots is
not caught by the assert; that case requires the table to be enabled.
Affected:
PPCBUG-108 legacy per-ctx reservation path cannot invalidate
cross-thread; informational — no behavioral change
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
d75c4edf67