How to get BUG working with multiple systems

Most people working with BUG device use R1.4 as their operating system. But I am not one of them.

Why? I am working on system which one day be R1.5 and to get it I need to have a way to boot different systems on BUG. But how to do that?

Few things are required:

U-Boot (which is required for R1.5 and optional for R1.4)
microSD card (which is required anyway)
images of different operating systems
card reader
some time

First of all we need to split microSD card to few partitions. I use default 2GB one so split it to 4 equal parts -- each for other version of BUG Linux. There are lot of applications which can be used so choose preferred one. Now we need to install misc systems to our card.

On first partition I put Ångström image which I built with org.openembedded.dev branch of OpenEmbedded. This is what I use for testing any of required tweaks. This image do not contains Java stuff - just bare console system. Adding X11 is in progress.

On 2nd partition I installed from official image. This one is to check how things were working in R1.4 and also to check do everything works like it should.

3rd partition keeps R1.5 built with stable/2009 branch of OpenEmbedded. This is what will be used as R1.5 sooner or later. It contains Java stuff as I use it with meta-but and meta-jalimo directories.

Not decided yet what will end on last partition ;)

OK, but how to boot selected system? It is easy with U-Boot as we have u-boot-utils package which allows to manipulate bootloader configuration from working system. So all I have to change is "bootargs" variable and reboot.

What left to fix? Kernel location because currently I use one uImage for all systems. Fix should be easy anyway :D