vms-ff7 (P4-A): lock manager compiled into the NetBSD vms module — real exec_rbtree backend

[baron-3dl]

Completes the NetBSD executive backend set (last facility, epic vms-8e8 P4-A) → unblocks the executive-on-VAX compile (B1, vms-20b9).

What

src/kernel-core/vms_lock.c — the shared distributed lock manager ($ENQ/$DEQ/$CONVERT/$GETLKI + DLM directory/mastering) — now compiles into the OVMX/NetBSD vms pseudo-device from the same source the Linux vms.ko runs. One facility, two substrates (INV-DRIFT); Linux behaviour untouched.

The real exec_rbtree NetBSD backend (the main new work)

vms_lock.c is the sole exec_rbtree consumer (its lock-ID tree) and drives a low-level, caller-descended contract (exec_rb_left/right + exec_rb_link_node/insert_color/erase) that NetBSD rb_tree(3)'s comparator API cannot back (design record §5 #2). So exec_rbtree_netbsd.c ships OVMX's own textbook red-black tree — the analogue of exec_list_netbsd.c / exec_hash_netbsd.c — with the packed parent+colour node the contract exposes.

Validated against a 4000-element random insert/erase stress harness: all red-black invariants (parent links, no red-red, equal black-height, BST order, root black) held through full deletion to empty.

Wiring (NetBSD backend only)

• vms_lock_nb.h — DLM wire contract: LCK_K_*/LCK_M_*, LCK_VALBLK_SIZE, four arg structs (all _IOWR, ≤104 B → no IOC_VOID big-io), request numbers byte-identical to Linux (V, NR 0x30–0x34), size asserts.
• vms_internal.h twin — struct vms_lock_entry/resource in exec_* vocabulary, proc lock fields, VMS_RES_HASH_BITS, lock SS$ codes, extern vms_local_csid, prototypes; includes exec_rbtree.h.
• vms_netbsd.c — defines vms_local_csid (glue, =1, as Linux vms_module.c); brings up/tears down proc lock fields; vms_proc_release_locks at proc death; vms_lock_init/cleanup in module lifecycle (cleanup frees entries, so proctab_teardown only destroys the guard — the eflag asymmetry); dispatches the five lock ioctls; drops the now-real weak rundown_locks stub.
• Makefile + crosscompile.sh — add vms_lock.c + exec_rbtree_netbsd.c to SRCS.

Verification

Per-PR gate "NetBSD/amd64 vms module cross-compiles" reproduced locally in a clang container against the pinned NetBSD/amd64 kernel headers: 10 TUs compile -Werror and relocatable-link clean (no dangling exec_rbtree_*/exec_*, no duplicate); negctl fails as it must. Lock logic not duplicated (only kernel-core/vms_lock.c); new .c lives in src/kernel-netbsd/ (excluded from the userspace_service_register host-compile, per the V3 gotcha).

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