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
@@ -196,6 +196,19 @@
 static session_t *find_session(pid_t);
 static DB *session_db;
 
+static void
+run_exec(char *path)
+{
+	char *argv[3];
+	char sh[] = "sh";
+
+	argv[0] = sh;
+	argv[1] = path;
+	argv[2] = NULL;
+
+	execute_script(argv);
+}
+
 /*
  * The mother of all processes.
  */
@@ -329,6 +342,11 @@
 	close(0);
 	close(1);
 	close(2);
+
+	if (kenv(KENV_GET, "init_exec", kenv_value, sizeof(kenv_value)) > 0) {
+		run_exec(kenv_value);
+		_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
@@ -492,6 +492,9 @@
 .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.