From 5e9cd1dbf8adbeddcedf697245d16430fb3bf569 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Sun, 5 Sep 2010 14:47:46 +0000
Subject: [PATCH] Document MAKEDEV_ETERNAL.

MFC after:	3 days
---
 share/man/man9/make_dev.9 | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/share/man/man9/make_dev.9 b/share/man/man9/make_dev.9
index 7faedaa4392..9cc755f5a95 100644
--- a/share/man/man9/make_dev.9
+++ b/share/man/man9/make_dev.9
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 6, 2010
+.Dd September 5, 2010
 .Dt MAKE_DEV 9
 .Os
 .Sh NAME
@@ -135,6 +135,7 @@ The following values are currently accepted:
 MAKEDEV_REF	reference the created device
 MAKEDEV_NOWAIT	do not sleep, may return NULL
 MAKEDEV_WAITOK	allow the function to sleep to satisfy malloc
+MAKEDEV_ETERNAL	created device will be never destroyed
 .Ed
 .Pp
 The
@@ -154,6 +155,18 @@ the device created is destroyed immediately after
 drops his reference to cdev.
 .Pp
 The
+.Dv MAKEDEV_ETERNAL
+flag allows the kernel to not acquire some locks when translating system
+calls into the cdevsw methods calls.
+It is responsibility of the driver author to make sure that
+.Fn destroy_dev
+is never called on the returned cdev.
+For the convenience, use the
+.Dv MAKEDEV_ETERNAL_KLD
+flag for the code that can be compiled into kernel or loaded
+(and unloaded) as loadable module.
+.Pp
+The
 .Fn make_dev_cred
 function is equivalent to the call
 .Bd -literal -offset indent