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 49b96c2..3ed095e 100644 (file)
--- 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 b45e8e0..d6cb3aa 100644 (file)
--- 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 fc7c707..fe3d747 100644 (file)
--- 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;