Add a new possible value for the machdep.allowaperture sysctl: `2'

allows access to the whole 1st megabyte of memory, for use by XFree86
4.0.x int10 code.  (ok, deraadt@) CVS:
----------------------------------------------------------------------
sys/arch/i386/i386/mem.c share/man/man4/man4.i386/xf86.4 CVS:
----------------------------------------------------------------------

2 files changed, 39 insertions, 8 deletions

diff --git a/share/man/man4/man4.i386/xf86.4 b/share/man/man4/man4.i386/xf86.4
index 0e38a7924c3..77d8eab6d2c 100644
--- a/share/man/man4/man4.i386/xf86.4
+++ b/share/man/man4/man4.i386/xf86.4
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: xf86.4,v 1.11 2000/11/10 20:02:18 todd Exp $
+.\"	$OpenBSD: xf86.4,v 1.12 2000/12/17 21:10:31 matthieu Exp $
 .\"
 .\" Copyright (c) 1998 Matthieu Herrb
 .\" All rights reserved.
@@ -47,11 +47,28 @@ Access to the
 .Pa /dev/xf86
 device is allowed when the sysctl variable
 .Va machdep.allowaperture
-= 1.
+>= 1.
 This variable (which default value is 0)
 can only be manipulated when the security level is <= 0, so it should be
 set in
 .Pa /etc/sysctl.conf .
+The possible values for 
+.Va machdep.allowaperture 
+are:
+.Bl -tag -width Ds
+.It 0
+the aperture driver is disabled. Opening it returns
+.Dv EPERM. 
+.It 1
+the aperture driver allows access to standard VGA framebuffer and
+BIOS.
+.It 2
+the aperture driver allow access to the whole 1st megabyte of physical
+memory, for the use of the int10 emulation in XFree86 4.0.x. 
+Note that this can cause some security problems, since the process that has
+access to the aperture driver can also access part of the kernel
+memory. 
+.El
 .Sh SEE ALSO
 .Xr XF86_Accel 1 ,
 .Xr XF86_SVGA 1 ,
diff --git a/sys/arch/i386/i386/mem.c b/sys/arch/i386/i386/mem.c
index f9c74f05c08..597f966112c 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 1.14 1999/11/20 11:11:28 matthieu Exp $ */
+/*	$OpenBSD: mem.c,v 1.15 2000/12/17 21:10:31 matthieu Exp $ */
 /*
  * Copyright (c) 1988 University of Utah.
  * Copyright (c) 1982, 1986, 1990, 1993
@@ -268,12 +268,26 @@ mmmmap(dev, off, prot)
 #ifdef APERTURE
 /* minor device 4 is aperture driver */
 	case 4:
-		if (allowaperture &&
-		    (((off >= VGA_START && off <= BIOS_END) ||
-		    (unsigned)off > (unsigned)ctob(physmem))))
-			return i386_btop(off);
-		else 
+		switch (allowaperture) {
+		case 1:
+			/* Allow mapping of the VGA framebuffer & BIOS only */
+			if ((off >= VGA_START && off <= BIOS_END) ||
+			    (unsigned)off > (unsigned)ctob(physmem))
+				return i386_btop(off);
+			else
+				return -1;
+		case 2:
+			/* Allow mapping of the whole 1st megabyte 
+			   for x86emu */
+			if (off <= BIOS_END || 
+			    (unsigned)off > (unsigned)ctob(physmem))
+				return i386_btop(off);
+			else 
+				return -1;
+		default:
 			return -1;
+		}
+			
 #endif
 	default:
 		return -1;