This is a request for testers, specifically people whose i386 or x86_64 systems won't boot properly if CONFIG_EDD=[ym] without the use of edd=skipmbr. If you're currently using edd=skipmbr, I'd really appreciate knowing about it, and your results of booting with this patch.
This patch uses an int13 Get Disk Type call before using a Read Sectors call to read the MBR. If Get Disk Type fails, this is a good indication that the BIOS doesn't believe there's a disk there, without actually trying to do I/O to the disk. arch/i386/boot/edd.S | 15 ++++++++++++++- include/linux/edd.h | 2 ++ 2 files changed, 16 insertions, 1 deletion Signed-off-by: Matt Domsch <[EMAIL PROTECTED]> Thanks, Matt -- Matt Domsch Software Architect Dell Linux Solutions linux.dell.com & www.dell.com/linux Linux on Dell mailing lists @ http://lists.us.dell.com diff --git a/arch/i386/boot/edd.S b/arch/i386/boot/edd.S --- a/arch/i386/boot/edd.S +++ b/arch/i386/boot/edd.S @@ -55,6 +55,19 @@ done_cl: # Read the first sector of each BIOS disk device and store the 4-byte signature edd_mbr_sig_start: movb $0x80, %dl # from device 80 +edd_get_disk_type: + movw $GET_DISK_TYPE, %ax + pushw %cx # this clobbers cx and dx + pushw %dx # + stc # work around buggy BIOSes + int $0x13 + sti # work around buggy BIOSes + popw %dx + popw %cx + jc edd_mbr_sig_done + cmpb $GET_DISK_TYPE_DISK, %ah # is this a disk? + jne edd_mbr_sig_done + movw $EDD_MBR_SIG_BUF, %bx # store buffer ptr in bx edd_mbr_sig_read: movl $0xFFFFFFFF, %eax @@ -82,7 +95,7 @@ edd_mbr_sig_read: incb %dl # increment to next device addw $4, %bx # increment sig buffer ptr cmpb $EDD_MBR_SIG_MAX, (EDD_MBR_SIG_NR_BUF) # Out of space? - jb edd_mbr_sig_read # keep looping + jb edd_get_disk_type # keep looping edd_mbr_sig_done: # Do the BIOS Enhanced Disk Drive calls diff --git a/include/linux/edd.h b/include/linux/edd.h --- a/include/linux/edd.h +++ b/include/linux/edd.h @@ -39,6 +39,8 @@ #define CHECKEXTENSIONSPRESENT 0x41 #define GETDEVICEPARAMETERS 0x48 #define LEGACYGETDEVICEPARAMETERS 0x08 +#define GET_DISK_TYPE 0x1500 +#define GET_DISK_TYPE_DISK 0x03 #define EDDMAGIC1 0x55AA #define EDDMAGIC2 0xAA55 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
