From: kettenis <kettenis@openbsd.org>
Date: Mon, 22 Jun 2015 18:57:26 +0000 (+0000)
Subject: Make it possible to create write combing mappings through /dev/mem.  This is
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=e1ad8ac791551d94856dd12b38f2b84b7e1a1f21;p=openbsd

Make it possible to create write combing mappings through /dev/mem.  This is
done by introducining a magic offset.  Pages below this offset are mapped
with default memory attributes.  Above this offset pages are mapped write
combining.

ok mlarkin@
---

diff --git a/sys/arch/amd64/amd64/mem.c b/sys/arch/amd64/amd64/mem.c
index 49b96c243e1..3ed095ec4c9 100644
--- a/sys/arch/amd64/amd64/mem.c
+++ b/sys/arch/amd64/amd64/mem.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mem.c,v 1.24 2015/05/28 20:53:05 jcs Exp $ */
+/*	$OpenBSD: mem.c,v 1.25 2015/06/22 18:57:26 kettenis Exp $ */
 /*
  * Copyright (c) 1988 University of Utah.
  * Copyright (c) 1982, 1986, 1990, 1993
@@ -205,6 +205,10 @@ mmmmap(dev_t dev, off_t off, int prot)
 #ifdef APERTURE
 /* minor device 4 is aperture driver */
 	case 4:
+		/* Check if a write combining mapping is requested. */
+		if (off >= MEMRANGE_WC_RANGE)
+			off = (off - MEMRANGE_WC_RANGE) | PMAP_WC;
+
 		switch (allowaperture) {
 		case 1:
 			/* Allow mapping of the VGA framebuffer & BIOS only */
diff --git a/sys/arch/i386/i386/mem.c b/sys/arch/i386/i386/mem.c
index b45e8e04df3..d6cb3aa1879 100644
--- a/sys/arch/i386/i386/mem.c
+++ b/sys/arch/i386/i386/mem.c
@@ -1,5 +1,5 @@
 /*	$NetBSD: mem.c,v 1.31 1996/05/03 19:42:19 christos Exp $	*/
-/*	$OpenBSD: mem.c,v 1.44 2015/05/28 20:53:05 jcs Exp $ */
+/*	$OpenBSD: mem.c,v 1.45 2015/06/22 18:57:26 kettenis Exp $ */
 /*
  * Copyright (c) 1988 University of Utah.
  * Copyright (c) 1982, 1986, 1990, 1993
@@ -219,6 +219,10 @@ mmmmap(dev_t dev, off_t off, int prot)
 #ifdef APERTURE
 /* minor device 4 is aperture driver */
 	case 4:
+		/* Check if a write combining mapping is requested. */
+		if (off >= MEMRANGE_WC_RANGE)
+			off = (off - MEMRANGE_WC_RANGE) | PMAP_WC;
+
 		switch (allowaperture) {
 		case 1:
 			/* Allow mapping of the VGA framebuffer & BIOS only */
diff --git a/sys/sys/memrange.h b/sys/sys/memrange.h
index fc7c707361d..fe3d74725fc 100644
--- a/sys/sys/memrange.h
+++ b/sys/sys/memrange.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: memrange.h,v 1.8 2013/12/19 21:30:02 deraadt Exp $ */
+/* $OpenBSD: memrange.h,v 1.9 2015/06/22 18:57:26 kettenis Exp $ */
 /*-
  * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
  * All rights reserved.
@@ -63,6 +63,9 @@ struct mem_range_op {
 #define MEMRANGE_GET	_IOWR('m', 50, struct mem_range_op)
 #define MEMRANGE_SET	_IOW('m', 51, struct mem_range_op)
 
+/* Offset indicating a write combining mapping is requested.  */
+#define MEMRANGE_WC_RANGE	0x4000000000000000ULL
+
 #ifdef _KERNEL
 
 struct mem_range_softc;