// away from the running binary image and then round up
// to a MB boundary.
want = (byte*)(((uintptr)end + (1<<18) + (1<<20) - 1)&~((1<<20)-1));
+ if(0xffffffff - (uintptr)want <= bitmap_size + arena_size)
+ want = 0;
p = runtime_SysReserve(want, bitmap_size + arena_size);
if(p == nil)
runtime_throw("runtime: cannot reserve arena virtual address space");