this diff changes the bootloader to skip the CHS sanity check if LBA

(EDD) is found and OK. it will also fix chainloading into OpenBSD from
grub in a few scenarios where grub doesn't report the CHS correctly
but the LBA. and we don't need CHS if there is LBA.

this has been in the snapshots for a while.

with input from weingart@
ok deraadt@

1 files changed, 15 insertions, 10 deletions

diff --git a/sys/arch/i386/stand/libsa/biosdev.c b/sys/arch/i386/stand/libsa/biosdev.c
index 9603fcb8ddd..2b8220225ac 100644
--- a/sys/arch/i386/stand/libsa/biosdev.c
+++ b/sys/arch/i386/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: biosdev.c,v 1.73 2008/06/25 15:26:44 reyk Exp $	*/
+/*	$OpenBSD: biosdev.c,v 1.74 2008/06/25 15:32:18 reyk Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -127,14 +127,6 @@ bios_getdiskinfo(int dev, bios_diskinfo_t *pdi)
 	pdi->bios_cylinders &= 0x3ff;
 	pdi->bios_cylinders++;
 
-	/* Sanity check */
-	if (!pdi->bios_cylinders || !pdi->bios_heads || !pdi->bios_sectors)
-		return 1;
-
-	/* CD-ROMs sometimes return heads == 1 */
-	if (pdi->bios_heads < 2)
-		return 1;
-
 	/* NOTE:
 	 * This currently hangs/reboots some machines
 	 * The IBM ThinkPad 750ED for one.
@@ -176,6 +168,18 @@ bios_getdiskinfo(int dev, bios_diskinfo_t *pdi)
 	} else
 		pdi->bios_edd = -1;
 
+	/* Skip sanity check for CHS options in EDD mode. */
+	if (pdi->bios_edd != -1)
+		return 0;
+
+	/* Sanity check */
+	if (!pdi->bios_cylinders || !pdi->bios_heads || !pdi->bios_sectors)
+		return 1;
+
+	/* CD-ROMs sometimes return heads == 1 */
+	if (pdi->bios_heads < 2)
+		return 1;
+
 	return 0;
 }
 
@@ -413,7 +417,8 @@ bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 	int n = 8;
 
 	/* Sanity check */
-	if (bd->bios_heads == 0 || bd->bios_sectors == 0)
+	if (bd->bios_edd == -1 &&
+	    (bd->bios_heads == 0 || bd->bios_sectors == 0))
 		return "failed to read disklabel";
 
 	/* MBR is a harddisk thing */