+dnl Features which may be selected in the following thread-detection switch.
+AH_TEMPLATE([PARALLEL_MARK], [Define to enable parallel marking.])
+AH_TEMPLATE([THREAD_LOCAL_ALLOC],
+ [Define to enable thread-local allocation optimisation.])
+AH_TEMPLATE([USE_COMPILER_TLS],
+ [Define to use of compiler-support for thread-local variables.])
+
+dnl Thread selection macros.
+AH_TEMPLATE([GC_THREADS], [Define to support threads.])
+AH_TEMPLATE([GC_AIX_THREADS], [Define to support IBM AIX threads.])
+AH_TEMPLATE([GC_DARWIN_THREADS], [Define to support Darwin pthreads.])
+AH_TEMPLATE([GC_FREEBSD_THREADS], [Define to support FreeBSD pthreads.])
+AH_TEMPLATE([GC_GNU_THREADS], [Define to support GNU pthreads.])
+AH_TEMPLATE([GC_HPUX_THREADS], [Define to support HP/UX 11 pthreads.])
+AH_TEMPLATE([GC_IRIX_THREADS], [Define to support Irix pthreads.])
+AH_TEMPLATE([GC_LINUX_THREADS], [Define to support pthreads on Linux.])
+AH_TEMPLATE([GC_NETBSD_THREADS], [Define to support NetBSD pthreads.])
+AH_TEMPLATE([GC_OPENBSD_THREADS], [Define to support OpenBSD pthreads.])
+AH_TEMPLATE([GC_OSF1_THREADS], [Define to support Tru64 pthreads.])
+AH_TEMPLATE([GC_SOLARIS_THREADS], [Define to support Solaris pthreads.])
+AH_TEMPLATE([GC_WIN32_THREADS], [Define to support win32 threads.])
+
+dnl System header feature requests.
+AH_TEMPLATE([_POSIX_C_SOURCE], [The POSIX feature macro.])
+AH_TEMPLATE([_PTHREADS], [Indicates the use of pthreads (NetBSD).])
+