[PATCH] Fix EDD to properly ignore signature of non-existing drives

Some BIOSes do not always set CF on error before return from int13.  The
patch adds additional check for status being zero (AH == 0).

Signed-off-by: Andrey Borzenkov <arvidjaar@mail.ru>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/boot/edd.S b/arch/i386/boot/edd.S
index d8d69f2..4b84ea2 100644 (file)
--- a/arch/i386/boot/edd.S
+++ b/arch/i386/boot/edd.S
@@ -76,6 +76,8 @@ edd_mbr_sig_read:
        popw    %es
        popw    %bx
        jc      edd_mbr_sig_done                # on failure, we're done.
+       cmpb    $0, %ah         # some BIOSes do not set CF
+       jne     edd_mbr_sig_done                # on failure, we're done.
        movl    (EDDBUF+EDD_MBR_SIG_OFFSET), %eax # read sig out of the MBR
        movl    %eax, (%bx)                     # store success
        incb    (EDD_MBR_SIG_NR_BUF)            # note that we stored something