In order to have a separate partition for Debian, I tried to repartition mmcblk0p4.
* umount /mnt/us
* umount /mnt/base-us
* fdisk /dev/mmcblk0p4
** deleting partition 4
** adding new extended partition
** adding new partition for us
** adding new partition for Debian
** writing partition table
Then I wanted to modify /etc/fstab.
I should have looked at it first. /mnt/base-us is loop-mounted and this was done in an upstart-script which calls lipc* (can't remember the details - it was late last night).
As I could not find a way to tell the system to mount mmcblk0p5 instead of p4, I restored the original partition table and reflashed mmcblk0p4 (because it was damaged by fdisk). I had some troubles to get the Kindle working again. Could not figure out why - maybe low batteries.
Now it is working again.
Keeping the partition numbering the same seems to be necessary to get Kindle running after repartitioning. Therefore I am thinking about deleting the diags partition putting debian there and leave the rest unchanged. Maybe I am lucky and can boot into Debian without much effort - so to get my "rescue" partition back.
One problem might be the changed file size of mmcblk0p4. I hope the Kindle system recognizes that and handles it correctly.
Any suggestions? Comments?