[syslinux:syslinux-4.xx] mbr/isohdpfx.S: Clear CX on INT 13h AH 41h failure

[syslinux-bot for Martin Str|mberg]

Commit-ID:  2d6ffa1412081c6b33ec2ef779d7e52c0bafbe15
Gitweb:     http://www.syslinux.org/commit/2d6ffa1412081c6b33ec2ef779d7e52c0bafbe15
Author:     Martin Str|mberg <ams at ludd.ltu.se>
AuthorDate: Sun, 26 Mar 2017 07:54:29 -0400
Committer:  Gene Cumm <gene.cumm at gmail.com>
CommitDate: Sat, 15 Apr 2017 13:24:39 -0400

mbr/isohdpfx.S: Clear CX on INT 13h AH 41h failure

If anything goes wrong, clear CX in case it contains garbage.

Signed-off-by: Gene Cumm <gene.cumm at gmail.com>

---
 mbr/isohdpfx.S | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mbr/isohdpfx.S b/mbr/isohdpfx.S
index f9e9691..4b107e4 100644
--- a/mbr/isohdpfx.S
+++ b/mbr/isohdpfx.S
@@ -167,8 +167,10 @@ next:
 	   read_sector_cbios: movb $0x42, %ah ;  jmp read_common */
 	movl	$0xeb42b4+((read_common-read_sector_cbios-4) << 24), \
 		(read_sector_cbios)
-	jmp	1f
+	jmp	2f
 1:
+	xor	%cx, %cx	/* Clear EBIOS flag. */
+2:
 	popw	%dx
 	pushw	%cx		/* EBIOS flag */