MFC r197608:

The first 96 bytes may not be zeroes. It can contain trivial boot
code that merely emits an error and waits for a key press before
rebooting. The error being that extended partitions are not
bootable. The origin is presumed to be Windows 2000; Windows XP
does not do this...

For now, ignore the first 96 bytes when checking that the EBR is
(for the most part) all zeroes.

Tested by:	Mario Lobo <mlobo at digiart.art.br>
		Dieter <dieterbsd at engineer.com>
PR:		kern/141235
Reviewed by:	marcel
Approved by:	kib (mentor)
Approved by:	re (bz)

1 files changed, 5 insertions, 5 deletions

diff --git a/sys/geom/part/g_part_ebr.c b/sys/geom/part/g_part_ebr.c
index ab04866cfd20..b107e6120c07 100644
--- a/sys/geom/part/g_part_ebr.c
+++ b/sys/geom/part/g_part_ebr.c
@@ -410,13 +410,13 @@ g_part_ebr_probe(struct g_part_table *table, struct g_consumer *cp)
 		goto out;
 
 	/*
-	 * The sector is all zeroes, except for the partition entries
-	 * and some signatures or disk serial number. Those can be
-	 * found in the 9 bytes immediately in front of the partition
-	 * table.
+	 * The sector is all zeroes, except for the partition entries,
+	 * pseudo boot code and some signatures or disk serial number.
+	 * The latter can be found in the 9 bytes immediately in front
+	 * of the partition table.
 	 */
 	sum = 0;
-	for (index = 0; index < DOSPARTOFF - 9; index++)
+	for (index = 96; index < DOSPARTOFF - 9; index++)
 		sum += buf[index];
 	if (sum != 0)
 		goto out;