+# ifdef DARWIN
+# define OS_TYPE "DARWIN"
+# define DARWIN_DONT_PARSE_STACK
+# define DYNAMIC_LOADING
+ /* XXX: see get_end(3), get_etext() and get_end() should not be used.
+ These aren't used when dyld support is enabled (it is by default) */
+# define DATASTART ((ptr_t) get_etext())
+# define DATAEND ((ptr_t) get_end())
+# ifdef HAVE_PTHREAD_GET_STACKADDR_NP
+# define STACKBOTTOM (ptr_t)pthread_get_stackaddr_np(pthread_self())
+# else
+# define STACKBOTTOM ((ptr_t) 0x7fff5fc00000)
+# endif
+# define USE_MMAP
+# define USE_MMAP_ANON
+# ifdef GC_DARWIN_THREADS
+# define MPROTECT_VDB
+# endif
+# include <unistd.h>
+# define GETPAGESIZE() getpagesize()
+ /* There seems to be some issues with trylock hanging on darwin. This
+ should be looked into some more */
+# define NO_PTHREAD_TRYLOCK
+# endif
+# ifdef FREEBSD
+# define OS_TYPE "FREEBSD"
+# ifndef GC_FREEBSD_THREADS
+# define MPROTECT_VDB
+# endif
+# ifdef __GLIBC__
+# define SIG_SUSPEND (32+6)
+# define SIG_THR_RESTART (32+5)
+ extern int _end[];
+# define DATAEND (_end)
+# else
+# define SIG_SUSPEND SIGUSR1
+# define SIG_THR_RESTART SIGUSR2
+# endif
+# define FREEBSD_STACKBOTTOM
+# ifdef __ELF__
+# define DYNAMIC_LOADING
+# endif
+ extern char etext[];
+ extern char * GC_FreeBSDGetDataStart();
+# define DATASTART GC_FreeBSDGetDataStart(0x1000, &etext)
+# endif