+extern nat mutlist_MUTVARS, mutlist_MUTARRS, mutlist_MVARS, mutlist_OTHERS;
+#endif
+
+#ifdef THREADED_RTS
+extern SpinLock gc_alloc_block_sync;
+#endif
+
+#if defined(PROF_SPIN) && defined(THREADED_RTS)
+extern StgWord64 whitehole_spin;
+#endif
+
+void gcWorkerThread (Capability *cap);
+void initGcThreads (void);
+void freeGcThreads (void);
+
+#if defined(THREADED_RTS)
+void waitForGcThreads (Capability *cap);
+void releaseGCThreads (Capability *cap);