Index: sbin/init/init.8
===================================================================
--- sbin/init/init.8
+++ sbin/init/init.8
@@ -316,6 +316,14 @@
 .Xr reboot 8
 .Fl r
 for details.
+.It Va init_exec
+If set to a valid file name in the root file system,
+instructs
+.Nm
+to directly execute that file as the very first action,
+replacing
+.Nm
+as PID 1.
 .It Va init_script
 If set to a valid file name in the root file system,
 instructs
@@ -341,6 +349,8 @@
 The default is
 .Dq Li /bin/sh .
 It is used for running the
+.Va init_exec
+or
 .Va init_script
 if set, as well as for the
 .Pa /etc/rc
Index: sbin/init/init.c
===================================================================
--- sbin/init/init.c
+++ sbin/init/init.c
@@ -330,6 +330,18 @@
 	close(1);
 	close(2);
 
+	if (kenv(KENV_GET, "init_exec", kenv_value, sizeof(kenv_value)) > 0) {
+		char *_argv[3];
+		char _sh[] = "sh";
+
+		_argv[0] = _sh;
+		_argv[1] = kenv_value;
+		_argv[2] = NULL;
+
+		execute_script(_argv);
+		_exit(0);		/* reboot */
+	}
+
 	if (kenv(KENV_GET, "init_script", kenv_value, sizeof(kenv_value)) > 0) {
 		state_func_t next_transition;
 
Index: stand/man/loader.8
===================================================================
--- stand/man/loader.8
+++ stand/man/loader.8
@@ -480,6 +480,9 @@
 .It Va init_chroot
 See
 .Xr init 8 .
+.It Va init_exec
+See
+.Xr init 8 .
 .It Va init_path
 Sets the list of binaries which the kernel will try to run as the initial
 process.