[src/trunk]: src/sys/dev/acpi Add a comment.

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

details:   https://anonhg.NetBSD.org/src/rev/b1bc88d2ed2a
branches:  trunk
changeset: 763348:b1bc88d2ed2a
user:      jruoho <jruoho%NetBSD.org@localhost>
date:      Thu Mar 17 15:32:18 2011 +0000

description:
Add a comment.

diffstat:

 sys/dev/acpi/acpi_cpu_cstate.c |  9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diffs (30 lines):

diff -r 87168fc1e22a -r b1bc88d2ed2a sys/dev/acpi/acpi_cpu_cstate.c
--- a/sys/dev/acpi/acpi_cpu_cstate.c    Thu Mar 17 14:42:58 2011 +0000
+++ b/sys/dev/acpi/acpi_cpu_cstate.c    Thu Mar 17 15:32:18 2011 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: acpi_cpu_cstate.c,v 1.50 2011/03/04 09:28:34 jruoho Exp $ */
+/* $NetBSD: acpi_cpu_cstate.c,v 1.51 2011/03/17 15:32:18 jruoho Exp $ */
 
 /*-
  * Copyright (c) 2010, 2011 Jukka Ruohonen <jruohonen%iki.fi@localhost>
@@ -27,7 +27,7 @@
  * SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: acpi_cpu_cstate.c,v 1.50 2011/03/04 09:28:34 jruoho Exp $");
+__KERNEL_RCSID(0, "$NetBSD: acpi_cpu_cstate.c,v 1.51 2011/03/17 15:32:18 jruoho Exp $");
 
 #include <sys/param.h>
 #include <sys/cpu.h>
@@ -345,6 +345,11 @@
 
                case ACPI_STATE_C1:
 
+                       /*
+                        * If ACPI wants native access (FFH), but the
+                        * MD code does not support MONITOR/MWAIT, use
+                        * HLT for C1 and error out for higher C-states.
+                        */
                        if ((sc->sc_flags & ACPICPU_FLAG_C_FFH) == 0)
                                state.cs_method = ACPICPU_C_STATE_HALT;