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Commit 6cdcdb99 authored by Andrey Borzenkov's avatar Andrey Borzenkov Committed by H. Peter Anvin
Browse files

x86 setup: fix ghost entries under /sys/firmware/edd take 3 

Some BIOSes do not indicate error when trying to read from non-
existing device. Zero buffer before reading and check that we
possibly have valid MBR by looking for MBR magic.

This was fixed in different way 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: default avatarAndrey Borzenkov &lt; <arvidjaar@mail.ru>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 464f04c9

arch/x86/boot/edd.c

+6 −1
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig) 
	char *mbrbuf_ptr, *mbrbuf_end;

	u32 buf_base, mbr_base;

	extern char _end[];

	u16 mbr_magic;



	sector_size = ei->params.bytes_per_sector;

	if (!sector_size)
@@ -60,11 +61,15 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig) 
	if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)

		return -1;



	memset(mbrbuf_ptr, 0, sector_size);

	if (read_mbr(devno, mbrbuf_ptr))

		return -1;



	*mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];

	return 0;

	mbr_magic = *(u16 *)&mbrbuf_ptr[510];



	/* check for valid MBR magic */

	return mbr_magic == 0xAA55 ? 0 : -1;

}



static int get_edd_info(u8 devno, struct edd_info *ei)