diff --git a/ObsoleteFiles.inc b/ObsoleteFiles.inc
--- a/ObsoleteFiles.inc
+++ b/ObsoleteFiles.inc
@@ -40,6 +40,9 @@
 #   xargs -n1 | sort | uniq -d;
 # done
 
+# 20210923: rename boot(9) to kern_reboot(9)
+OLD_FILES+=usr/share/man/man9/boot.9.gz
+
 # 20210921: remove cloudabi
 OLD_FILES+=usr/share/man/man4/cloudabi.4.gz
 
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -15,7 +15,6 @@
 	bhnd_erom.9 \
 	bios.9 \
 	bitset.9 \
-	boot.9 \
 	bpf.9 \
 	buf.9 \
 	buf_ring.9 \
@@ -195,6 +194,7 @@
 	ithread.9 \
 	kasan.9 \
 	KASSERT.9 \
+	kern_reboot.9 \
 	kern_testfrwk.9 \
 	kernacc.9 \
 	kernel_mount.9 \
diff --git a/share/man/man9/boot.9 b/share/man/man9/kern_reboot.9
rename from share/man/man9/boot.9
rename to share/man/man9/kern_reboot.9
--- a/share/man/man9/boot.9
+++ b/share/man/man9/kern_reboot.9
@@ -34,21 +34,25 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 14, 1997
-.Dt BOOT 9
+.Dd Sept 23, 2021
+.Dt KERN_REBOOT 9
 .Os
 .Sh NAME
-.Nm boot
+.Nm kern_reboot
 .Nd halt or reboot the system
 .Sh SYNOPSIS
 .In sys/types.h
 .In sys/systm.h
 .In sys/reboot.h
 .Ft void
-.Fn boot "int howto"
+.Fn kern_reboot "int howto"
+.In sys/eventhandler.h
+.Fn EVENTHANDLER_REGISTER "shutdown_pre_sync" "shutdown_fn" "private" "priority"
+.Fn EVENTHANDLER_REGISTER "shutdown_post_sync" "shutdown_fn" "private" "priority"
+.Fn EVENTHANDLER_REGISTER "shutdown_final" "shutdown_fn" "private" "priority"
 .Sh DESCRIPTION
 The
-.Fn boot
+.Fn kern_reboot
 function handles final system shutdown, and either halts or reboots
 the system.
 The exact action to be taken is determined by the flags passed in
@@ -56,12 +60,12 @@
 and by whether or not the system has finished autoconfiguration.
 .Pp
 If the system has finished autoconfiguration,
-.Fn boot
+.Fn kern_reboot
 does the following:
 .Bl -enum -offset indent
 .It
 If this is the first invocation of
-.Fn boot
+.Fn kern_reboot
 and the
 .Dv RB_NOSYNC
 flag is not set in
@@ -93,8 +97,14 @@
 .El
 .Pp
 If the system has not finished autoconfiguration,
-.Fn boot
+.Fn kern_reboot
 runs any shutdown hooks previously registered,
 prints a message, and halts the system.
+.Sh RETURN VALUES
+The
+.Fn kern_reboot
+function does not return.
 .Sh SEE ALSO
+.Xr reboot 2
+.Xr EVENTHANDLER 9
 .Xr vfs_unmountall 9
diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -421,7 +421,8 @@
 }
 
 /*
- * Shutdown the system cleanly to prepare for reboot, halt, or power off.
+ * kern_reboot(9): Shut down the system cleanly to prepare for reboot, halt, or
+ * power off.
  */
 void
 kern_reboot(int howto)
@@ -450,7 +451,7 @@
 		sched_bind(curthread, CPU_FIRST());
 		thread_unlock(curthread);
 		KASSERT(PCPU_GET(cpuid) == CPU_FIRST(),
-		    ("boot: not running on cpu 0"));
+		    ("%s: not running on cpu 0", __func__));
 	}
 #endif
 	/* We're in the process of rebooting. */