[eureka]

Originally Posted by EternalCyclist

When you mount the new ext3 partition you do not use the entries of the partitiontable in mmcblk0p4. This means there is a discrepancy between that partition table and the actual start of the ext3 partition?

There is a disrcepancy between start of free partition (/dev/mmcblk0p4p2) and start of ext3 filesystem. Or, in other words, there is a little free space (<= 4MB) between of start of that parition and actual start of ext3 filesystem to compensate misaligning of partition.

But it's:

• unintentional (I just didn't think about aligning at writing of first post)
• not required at all (I guess without aligning at 4MB nothing really bad will happen, maybe, just pereformace will degrade)

Anyway, this free space could be eliminated via extending of /dev/mmcblk0p4p1 (userstore parition) and re-initing it. I mean, just initialize PART_SIZE in diff from my "first" post with a bit larger value (UPD: exactly 2101232). Then /dev/mmcblk0p4p2 will be aligned on 4MB.

Also, I don't use entries from parition table at /dev/mmcblk0p4, because I don't know how to do it. I believe, it's not possilble at all. /dev/mmcblk0p4 is the partition, not the separate block device. Tools just don't know anything about that "embedded" paritition table and they couldn't be pointed at it.

Originally Posted by EternalCyclist

This calculated offset could be written into the partition table on mmcblk0p4, so that mounting the ext3 partition on the host can be done without the offset option?

Explicit offset is required, because location of that new partition is unknown to OS (because it can't access parition table at /dev/mmcblk0p4), not because of some disrcepancy.

Originally Posted by EternalCyclist

Why do I have to mount it via /dev/loop?
What about simply doing "mount -o offset=1075838976 /dev/mmcblk0p4 /somehwere" ?

You could mount with your command. With losetup loop device is chosen by you, and with your command loop device is chosen by mount tool. It's the sole difference, AFAIK.