Skip memory areas smaller than 1 MB above the 16 MB boundary to deal with

buggy ACP BIOSes.  Based on a diff from weingart@.

ok deraadt@, oga@

2 files changed, 23 insertions, 9 deletions

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index b87d7509213..418903872c9 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.83 2008/10/06 21:05:56 kettenis Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.84 2008/10/09 19:04:18 kettenis Exp $	*/
 /*	$NetBSD: machdep.c,v 1.3 2003/05/07 22:58:18 fvdl Exp $	*/
 
 /*-
@@ -1305,6 +1305,17 @@ init_x86_64(paddr_t first_avail)
 		e1 = trunc_page(bmp->addr + bmp->size);
 		s2 = e2 = 0; s3 = e3 = 0; s4 = e4 = 0;
 
+		/*
+		 * XXX Some buggy ACPI BIOSes use memory that they
+		 * declare as free.  Typically the affected memory
+		 * areas are small blocks between areas reserved for
+		 * ACPI and other BIOS goo.  So skip areas smaller
+		 * than 1 MB above the 16 MB boundary (to avoid
+		 * affecting legacy stuff).
+		 */
+		if (s1 > 16*1024*1024 && (e1 - s1) < 1*1024*1024)
+			continue;
+
 		/* Check and adjust our segment(s) */
 		/* Nuke page zero */
 		if (s1 < avail_start) {
diff --git a/sys/arch/i386/i386/machdep.c b/sys/arch/i386/i386/machdep.c
index 87e091c6ec0..80b7c6f392b 100644
--- a/sys/arch/i386/i386/machdep.c
+++ b/sys/arch/i386/i386/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.436 2008/10/06 19:46:21 kettenis Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.437 2008/10/09 19:04:18 kettenis Exp $	*/
 /*	$NetBSD: machdep.c,v 1.214 1996/11/10 03:16:17 thorpej Exp $	*/
 
 /*-
@@ -3005,8 +3005,8 @@ init386(paddr_t first_avail)
 			if (a < 8 * NBPG)
 				a = 8 * NBPG;
 
-			/* skip regions which are zero or negative in size */
-			if (a >= e) {
+			/* skip shorter than page regions */
+			if (a >= e || (e - a) < NBPG) {
 #ifdef DEBUG
 				printf("-S");
 #endif
@@ -3014,12 +3014,15 @@ init386(paddr_t first_avail)
 			}
 
 			/*
-			 * XXX - This is a hack to work around BIOS bugs and
-			 * a bug in the  msgbuf allocation.  We skip regions
-			 * smaller than the message buffer or 16-bit segment
-			 * limit in size.
+			 * XXX Some buggy ACPI BIOSes use memory that
+			 * they declare as free.  Typically the
+			 * affected memory areas are small blocks
+			 * between areas reserved for ACPI and other
+			 * BIOS goo.  So skip areas smaller than 1 MB
+			 * above the 16 MB boundary (to avoid
+			 * affecting legacy stuff).
 			 */
-			if ((e - a) < max((MSGBUFSIZE / NBPG), (64 * 1024))) {
+			if (a > 16*1024*1024 && (e - a) < 1*1024*1024) {
 #ifdef DEBUG
 				printf("-X");
 #endif