1 files changed, 78 insertions, 21 deletions

diff --git a/sys/arch/amd64/stand/libsa/biosdev.c b/sys/arch/amd64/stand/libsa/biosdev.c
index 696acf81d24..0e4439c8296 100644
--- a/sys/arch/amd64/stand/libsa/biosdev.c
+++ b/sys/arch/amd64/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: biosdev.c,v 1.4 2007/04/04 14:36:05 jmc Exp $	*/
+/*	$OpenBSD: biosdev.c,v 1.5 2008/06/25 15:26:44 reyk Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -45,6 +45,9 @@ static int biosdisk_errno(u_int);
 static int CHS_rw (int, int, int, int, int, int, void *);
 static int EDD_rw (int, int, u_int64_t, u_int32_t, void *);
 
+static daddr_t findopenbsd(bios_diskinfo_t *, daddr_t, daddr_t *,
+    const char **, int *);
+
 extern int debug;
 int bios_bootdev;
 int bios_cddev = -1;		/* Set by srt0 if coming from CD */
@@ -335,13 +338,76 @@ biosd_io(int rw, bios_diskinfo_t *bd, daddr_t off, int nsect, void *buf)
 /*
  * Try to read the bsd label on the given BIOS device
  */
+static daddr_t
+findopenbsd(bios_diskinfo_t *bd, daddr_t off, daddr_t *roff, const char **err,
+    int *n)
+{
+	int error, i;
+	struct dos_mbr mbr;
+	struct dos_partition *dp;
+
+	/* Limit the number of recursions */
+	if (!(*n)--) {
+		*err = "too many extended partitions";
+		return (0);
+	}
+
+	/* Read MBR */
+	error = biosd_io(F_READ, bd, off, 1, &mbr);
+	if (error) {
+		*err = biosdisk_err(error);
+		return (0);
+	}
+
+	/* check mbr signature */
+	if (mbr.dmbr_sign != DOSMBR_SIGNATURE) {
+		*err = "bad MBR signature\n";
+		return (0);
+	}
+
+	/* Search for OpenBSD partition */
+	for (off = 0, i = 0; off == 0 && i < NDOSPART; i++) {
+		dp = &mbr.dmbr_parts[i];
+#ifdef BIOS_DEBUG
+		if (debug)
+			printf("found partition %u: "
+			    "type %u (0x%x) offset %u (0x%x)\n",
+			    (int)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+#endif
+		if (dp->dp_typ == DOSPTYP_OPENBSD)
+			off = dp->dp_start;
+		else if (dp->dp_typ == DOSPTYP_EXTEND ||
+		    dp->dp_typ == DOSPTYP_EXTENDL) {
+			off = findopenbsd(bd, dp->dp_start, roff, err, n);
+			if (off != 0)
+				*roff = dp->dp_start;
+		}
+	}
+
+#ifdef BIOS_DEBUG
+	if (debug)
+		printf("using offset %u\n", off);
+#endif
+
+	if (off == 0) {
+		if (*err == NULL)
+			*err = "no OpenBSD partition\n";
+		return (0);
+	}
+
+	return (off);
+}
+
 const char *
 bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 {
-	daddr_t off = LABELSECTOR;
+	daddr_t off = 0, roff = 0;
 	char *buf;
-	struct dos_mbr mbr;
-	int error, i;
+	const char *err = NULL;
+	int error;
+	int n = 8;
 
 	/* Sanity check */
 	if(bd->bios_heads == 0 || bd->bios_sectors == 0)
@@ -349,23 +415,14 @@ bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 
 	/* MBR is a harddisk thing */
 	if (bd->bios_number & 0x80) {
-		/* Read MBR */
-		error = biosd_io(F_READ, bd, DOSBBSECTOR, 1, &mbr);
-		if (error)
-			return(biosdisk_err(error));
-
-		/* check mbr signature */
-		if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
-			return("bad MBR signature\n");
-
-		/* Search for OpenBSD partition */
-		for (off = 0, i = 0; off == 0 && i < NDOSPART; i++)
-			if (mbr.dmbr_parts[i].dp_typ == DOSPTYP_OPENBSD)
-				off = mbr.dmbr_parts[i].dp_start + LABELSECTOR;
-		if (off == 0)
-			return("no OpenBSD partition\n");
-	} else
-		off = LABELSECTOR;
+		off = findopenbsd(bd, DOSBBSECTOR, &roff, &err, &n);
+		if (off == 0) {
+			if (err != NULL)
+				return (err);
+ 			return "no OpenBSD partition\n";
+		}
+	}
+	off = LABELSECTOR + off + roff;
 
 	/* Load BSD disklabel */
 	buf = alloca(DEV_BSIZE);