extern int _etext[];
# define DATAEND (_end)
# define SVR4
+# define LINUX_STACKBOTTOM
# ifdef __arch64__
-# define STACKBOTTOM ((ptr_t) 0x80000000000ULL)
# define DATASTART (ptr_t)GC_SysVGetDataStart(0x100000, _etext)
# else
-# define STACKBOTTOM ((ptr_t) 0xf0000000)
# define DATASTART (ptr_t)GC_SysVGetDataStart(0x10000, _etext)
# endif
# endif