Commit 464f04c9 authored Sep 06, 2008 by Andrey Borzenkov Committed by Ingo Molnar Sep 06, 2008

x86: fix ghost EDD devices in /sys again

> This is regression but old enough. Apparently I had for whatever reasons
> EDD turned off till recently. This is 2.6.27-rc5 just in case.
>
> In 2006 I fixed ghost devices due to buggy BIOS:
>
> http://marc.info/?l=linux-kernel&m=114087765422490&w=2
>
> Later edd.S has been rewritten in C, and apparently this patch has been
> lost:
>
> {pts/1}% ls /sys/firmware/edd
> int13_dev80/  int13_dev84/  int13_dev88/  int13_dev8c/
> int13_dev81/  int13_dev85/  int13_dev89/  int13_dev8d/
> int13_dev82/  int13_dev86/  int13_dev8a/  int13_dev8e/
> int13_dev83/  int13_dev87/  int13_dev8b/  int13_dev8f/
>
> But I have just a single disk. This is the same system BTW.

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

This was fixed for edd.S in
http://marc.info/?l=linux-kernel&m=114087765422490&w=2

, but lost
again when edd.S was rewritten in C.

Signed-off-by: Andrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent d2f37384

arch/x86/boot/edd.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -32,7 +32,9 @@ static int read_mbr(u8 devno, void *buf)
		: "+a" (ax), "+c" (cx), "+d" (dx), "+b" (bx)
		: : "esi", "edi", "memory");

		return -(u8)ax; /* 0 or -1 */
		/* Some BIOSes do not set carry flag on error but still return
		* error in AH. The condition below is expected to catch both */
		return -!!ax; /* 0 or -1 */
		}

		static u32 read_mbr_sig(u8 devno, struct edd_info ei, u32 mbrsig)

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