[parted-devel] [PATCH 5/6] libparted: handle logical partitions starting immediately after the EBR

[Phillip Susi]

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On 12/15/2012 08:23 PM, Jim Meyering wrote:
> Phillip Susi wrote:
>> _blkpg_add_partition() set the length of the extended partition 
>> to 2 sectors to allow LILO to be installed there, beacuse the 
>> linux kernel does this.  If a logical partition used that second 
>> sector, adding it would fail beacuse of the overlap.  Now 
>> _blkpg_add_partition() will limit the length to only the first 
>> sector if the second is used by a logical partition.
> 
> Hi Phillip,
> 
> Thanks for your patience. I have a couple questions about this
> change: - why?  The commit log (or perhaps comments in the code)
> should tell us why this change is desirable.

To allow for a partition to start on the first sector following the
MBR, which is a perfectly legal configuration.

> - if we make this change, won't that let parted create partition
> tables that cause older linux kernels to object?

No, the kernel has never objected to such an on disk partition layout.
 What it objects to is being told about it via BLKPG.  When it
encounters such an on disk layout, it happily accepts it and generates
two overlapping partitions in memory.

> - if you do change the code not to require the 2-sector "size", 
> please also change the name of that test script.
> 
>> libparted/arch/linux.c                          |   10
>> +++++++++- tests/t2310-dos-extended-2-sector-min-offset.sh |   20
>> ++++----------------

So you suggest renaming it to 23210-dos-extended-1-sector-offset.sh?



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