By now I'm pretty sure that this problem is due to the alignment code.
It goes like this:
1. ped_disk_add_partition() is called to add the partition. The
constraint which is passed to it is computed in
ped_device_get_optimum_alignment():
/* Align to a grain of 1MiB (like vista / win7) */
align = ped_alignment_new(0, 1048576 / dev->sector_size);
As dev->sector_size is 512, we end up with alignment of offset 0 and
grain_size 2048, and the resulting constraint passed to
ped_disk_add_partition() has start_align set to {offset = 0;
grain_size=2048} and end_align set to {offset = 2047, grain_size =
2048). That looks normal.
2. _partition_align() is called to align the partition with this
constraint. This simply calls the disk-specific partition_align
function, in this case sun_partition_align().
3. In sun_partition_align: disk_specific->cylinder_alignment is set to
1, so the final alignment will be an intersection of our initial
constraint and _get_strict_constraint(part->disk).
4. In _get_strict_constraint() the alignment is determined by a
product of dev->bios_geom.sectors and dev->bios_geom.heads. In my case
the former is 63 and the latter is 255, so the resulting strict
alignment will enforce partition alignment to 63 * 255 = 16065
sectors.
5. An intersection of two constraints, one aligning to 2048 and
another aligning to 16065 sectors, is computed. The least common
multiple of those two happens to be their product, so a combined
constraint ends up to be forcing the alignment to 2048 * 16065 =
32901120 sectors, or 16.8G (!). Looking at the debugging dump, the
second partition during my install was placed at 16845373440, which is
exactly 2048 * 16065 * 512, which confirms the alignment issue.
I have no idea how it worked before, nor could I figure out why the
addition of first partition worked as expected.
Best regards,
--
Jurij Smakov ju...@wooyd.org
Key: http://www.wooyd.org/pgpkey/ KeyID: C99E03CC
--
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
