[src/trunk]: src/sys/arch/powerpc/oea clarify comment in previous

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

details:   https://anonhg.NetBSD.org/src/rev/f37b6095e3eb
branches:  trunk
changeset: 960922:f37b6095e3eb
user:      macallan <macallan%NetBSD.org@localhost>
date:      Fri Apr 02 16:59:59 2021 +0000

description:
clarify comment in previous
( this is a hack, should go away when the root cause is fixed etc. )
no functional change

diffstat:

 sys/arch/powerpc/oea/ofwoea_machdep.c |  13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diffs (34 lines):

diff -r ce4ab466e332 -r f37b6095e3eb sys/arch/powerpc/oea/ofwoea_machdep.c
--- a/sys/arch/powerpc/oea/ofwoea_machdep.c     Fri Apr 02 16:38:08 2021 +0000
+++ b/sys/arch/powerpc/oea/ofwoea_machdep.c     Fri Apr 02 16:59:59 2021 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: ofwoea_machdep.c,v 1.60 2021/04/01 22:02:20 macallan Exp $ */
+/* $NetBSD: ofwoea_machdep.c,v 1.61 2021/04/02 16:59:59 macallan Exp $ */
 
 /*-
  * Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ofwoea_machdep.c,v 1.60 2021/04/01 22:02:20 macallan Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ofwoea_machdep.c,v 1.61 2021/04/02 16:59:59 macallan Exp $");
 
 #include "ksyms.h"
 #include "wsdisplay.h"
@@ -379,9 +379,12 @@
                        continue;
 
                /*
-                * XXX
-                * my beige G3 throws a DSI trap if we try to map the last page
-                * of the firmware ROM
+                * XXX macallan@
+                * My beige G3 throws a DSI trap if we try to map the last page
+                * of the 32bit address space. On old world macs the firmware
+                * ROM occupies 4MB at 0xffc00000, triggering it when we 
+                * restore OF translations. This just works around a bug
+                * elsewhere in pmap and should go away once fixed there.
                 */
                if (pa == 0xffc00000 && size == 0x400000)
                        size = 0x3ff000;