When detecting a valid protective MBR, the Linux kernel isn't picky about the partition (1-4) the 0xEE is at, but, unlike other operating systems, it does require it to begin at the second sector (sector 1). This check, apart from it not being enforced by UEFI, and causing Linux to potentially fail to detect any *valid* partitions on the disk, can present problems when dealing with hybrid MBRs[1].
For compatibility reasons, if the first partition is hybridized, the 0xEE partition must be small enough to ensure that it only protects the GPT data structures - as opposed to the the whole disk in a protective MBR. This problem is very well described by Rod Smith[1]: where MBR-only partitioning programs (such as older versions of fdisk) can see some of the disk space as unallocated, thus loosing the purpose of the 0xEE partition's protection of GPT data structures. By dropping this check, this patch enables Linux to be more flexible when probing for GPT disklabels. [1] http://www.rodsbooks.com/gdisk/hybrid.html#reactions Signed-off-by: Davidlohr Bueso <davidl...@hp.com> --- block/partitions/efi.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/block/partitions/efi.c b/block/partitions/efi.c index 6a997b1..331cd1c 100644 --- a/block/partitions/efi.c +++ b/block/partitions/efi.c @@ -158,12 +158,9 @@ static inline int pmbr_part_valid(gpt_record *part) if (le32_to_cpu(part->starting_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA) goto invalid; - if (le32_to_cpu(part->start_sector) != 1UL) - goto invalid; - - return 1; + return 1; invalid: - return 0; + return 0; } /** -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
