[src/trunk]: src/sys/arch/amd64/amd64 cpu_setmcontext: add a comment

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/210bedbaf7bf
branches:  trunk
changeset: 758143:210bedbaf7bf
user:      yamt <yamt%NetBSD.org@localhost>
date:      Thu Oct 21 11:28:34 2010 +0000

description:
cpu_setmcontext: add a comment

diffstat:

 sys/arch/amd64/amd64/machdep.c |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (28 lines):

diff -r d3d1464b3e72 -r 210bedbaf7bf sys/arch/amd64/amd64/machdep.c
--- a/sys/arch/amd64/amd64/machdep.c    Thu Oct 21 11:27:46 2010 +0000
+++ b/sys/arch/amd64/amd64/machdep.c    Thu Oct 21 11:28:34 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: machdep.c,v 1.152 2010/10/21 11:27:46 yamt Exp $       */
+/*     $NetBSD: machdep.c,v 1.153 2010/10/21 11:28:34 yamt Exp $       */
 
 /*-
  * Copyright (c) 1996, 1997, 1998, 2000, 2006, 2007, 2008
@@ -107,7 +107,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.152 2010/10/21 11:27:46 yamt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.153 2010/10/21 11:28:34 yamt Exp $");
 
 /* #define XENDEBUG_LOW  */
 
@@ -1632,6 +1632,9 @@
                if (error != 0)
                        return error;
                /*
+                * save and restore some values we don't want to change.
+                * _FRAME_GREG(copy_to_tf) below overwrites them.
+                *
                 * XXX maybe inline this.
                 */
                rflags = tf->tf_rflags;