I'm using a customized .20 installer sd image which I turned into a fully bootable system where / and /boot is on the external sd.

The problem I have is how u-boot seems to boot from the external sd. I tried to understand the boot.scr on the installer image, but from what I read I don't know if the script overwrites the internal sd on every boot or what the heck it does. The part which worries me is that there are commands in it to erase the internal sd under specific conditions, which - if I want to change some files on the boot partition could quickly happen and brick my system. How can I make sure this doesn't happen?

A related problem is that I tried to build a custom kernel with everything built in to make future experiments easier, changed the necessary commands to fit, but the kernel isn't able to grab mmblck0p2 as root even thought it says it found it and for some reasons throws me into a initramfs shell (which I never told it to use). How can I boot a custom kernel standalone or with a custom initramfs?

It flashes U-Boot if it's out of date. It doesn't even go near the SD card; it talks to the SPI NOR.

Your custom installer needn't do anything of the sort. I suggest you go here:

https://bugs.launchpad.net/ubuntu/+sour ... omments/31

Download the boot.script and create your own little boot.scr from it.
We enabled rootwait by default so it should hang around forever waiting for it to appear. Make sure you really spelled it right; I can't type mmcblk0p2 right every time to save my life. Seeing as you didn't (above) my first thought is it's a typo.

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Matt Sealey

Thank you, it looks like mmcblk0p2 was the cause. Chopping of the complicated stuff from the boot.scr left me with what you linked and it works fine now. Now I don't need to worry that some random script wears out some soldered/internal flash/nor and turns my netbook into a (good looking) paperweight.