Subject: + partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1.patch added to -mm tree
To: davidlohr@xxxxxx,kzak@xxxxxxxxxx,matt.fleming@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 10 Sep 2013 17:09:03 -0700
The patch titled
Subject: partitions/efi: do not require gpt partition to begin at sector 1
has been added to the -mm tree. Its filename is
partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1.patch
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From: Davidlohr Bueso <davidlohr@xxxxxx>
Subject: partitions/efi: do not require gpt partition to begin at sector 1
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 <davidlohr@xxxxxx>
Reviewed-by: Karel Zak <kzak@xxxxxxxxxx>
Acked-by: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/partitions/efi.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff -puN block/partitions/efi.c~partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1 block/partitions/efi.c
--- a/block/partitions/efi.c~partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1
+++ a/block/partitions/efi.c
@@ -158,12 +158,9 @@ static inline int pmbr_part_valid(gpt_mb
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;
}
/**
_
Patches currently in -mm which might be from davidlohr@xxxxxx are
hugepage-mention-libhugetlbfs-in-doc.patch
mm-hugetlb-protect-reserved-pages-when-soft-offlining-a-hugepage.patch
mm-hugetlb-change-variable-name-reservations-to-resv.patch
mm-hugetlb-fix-subpool-accounting-handling.patch
mm-hugetlb-remove-useless-check-about-mapping-type.patch
mm-hugetlb-grab-a-page_table_lock-after-page_cache_release.patch
mm-hugetlb-return-a-reserved-page-to-a-reserved-pool-if-failed.patch
partitions-efi-use-lba-aware-partition-records.patch
partitions-efi-use-lba-aware-partition-records-fix.patch
partitions-efi-check-pmbr-records-starting-lba.patch
partitions-efi-do-not-require-gpt-partition-to-begin-at-sector-1.patch
partitions-efi-detect-hybrid-mbrs.patch
partitions-efi-account-for-pmbr-size-in-lba.patch
partitions-efi-compare-first-and-last-usable-lbas.patch
partitions-efi-delete-annoying-emacs-style-comments.patch
partitions-efi-some-style-cleanups.patch
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