selecting UBI boot partition on startup

[Deon Carr]

Hi, 

I am designing a high availability system that requires two copies of
the system software with uboot booting the kernel / rootfs of the most
recent software. 

My intended nand flash arrangement is along the lines of:

MTD0       MTD1
--------------------
UBOOT | UBI Layer
--------------------

The UBI layer will have two UBI volumes which will be formatted for
UBIFS. The intention is to package the kernel / rootfs and application
all in the single volume. 


What is the best method of selecting UBI volume to boot from in uboot?

I could store a boot flag in each UBIFS along with the kernel, however
this will require reading both volumes in uboot to determine which one
to boot from. An alternative is to create a third smaller UBI volume
which instructs which UBI volume to boot from.

Is there a better way of handling this? Is it possible to reorder the
UBI volumes dynamically? If this were possible I could have uboot always
boot UBI0 and just rearrange UBI0, UBI1 whenever I need change the
volume to boot from. 



Thanks in advance.

Deon