--- libgo/go/runtime/os_bsdsunix.go.orig	2020-03-04 19:30:03.000000000 +1100
+++ libgo/go/runtime/os_bsdsunix.go	2020-03-04 19:30:03.000000000 +1100
@@ -0,0 +1,67 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import (
+	"unsafe"
+)
+
+type mOS struct {
+	unused byte
+}
+
+//go:noescape
+//extern _umtx_op
+func sys_umtx_op(addr *uint32, mode int32, val uint32, uaddr1 uinptr, ts *umtx_time) int32
+
+func getPageSize() uintptr {
+	mib := [2]uint32{_CTL_HW, _HW_PAGESIZE}
+	out := uint32(0)
+	nout := unsafe.Sizeof(out)
+	ret := sysctl(&mib[0], 2, (*byte)(unsafe.Pointer(&out)), &nout, nil, 0)
+	if ret >= 0 {
+		return uintptr(out)
+	}
+	return 0
+}
+
+// FreeBSD's umtx_op syscall is effectively the same as Linux's futex, and
+// thus the code is largely similar. See Linux implementation
+// and lock_futex.go for comments.
+
+//go:nosplit
+func futexsleep(addr *uint32, val uint32, ns int64) {
+	systemstack(func() {
+		futexsleep1(addr, val, ns)
+	})
+}
+
+func futexsleep1(addr *uint32, val uint32, ns int64) {
+	var utp *umtx_time
+	if ns >= 0 {
+		var ut umtx_time
+		ut._clockid = _CLOCK_MONOTONIC
+		ut._timeout.set_sec(int64(timediv(ns, 1000000000, (*int32)(unsafe.Pointer(&ut._timeout.tv_nsec)))))
+		utp = &ut
+	}
+	ret := sys_umtx_op(addr, _UMTX_OP_WAIT_UINT_PRIVATE, val, unsafe.Sizeof(*utp), utp)
+	if ret >= 0 || ret == -_EINTR {
+		return
+	}
+	print("umtx_wait addr=", addr, " val=", val, " ret=", ret, "\n")
+	*(*int32)(unsafe.Pointer(uintptr(0x1005))) = 0x1005
+}
+
+//go:nosplit
+func futexwakeup(addr *uint32, cnt uint32) {
+	ret := sys_umtx_op(addr, _UMTX_OP_WAKE_PRIVATE, cnt, 0, nil)
+	if ret >= 0 {
+		return
+	}
+
+	systemstack(func() {
+		print("umtx_wake_addr=", addr, " ret=", ret, "\n")
+	})
+}