Re: [RAUC] Bootloader updates

[Martin Hollingsworth <Martin.Hollingsworth@itk-engineering.de>]

Hi Enrico,
thanks for the quick answer. I am using barebox with bootchoser and PTXdist for my linux.

> despite the fact that you might not want to update you bootloader with each rootFS update.
Indeed! I have to figure out a way to compare the installed bootloader with the shipped one and only update if necessary.

> Thus, after having updated your bootloader, it will read your previous configuration and know in which state you are!
Good to know, let's keep that in mind for the next section.
 
Ok, so let me rephrase my worries. So during an update, that includes a new bootloader, the following steps are done in the following order:
1) Update Bootloader by overwriting it (RAUC config stays intact).
2) Install RootFS onto second slot (say Slot B).

When 1) succeeds and 2) fails / is interrupted (power cut, etc.), the bootchoser configuration will decide to boot from Slot A again (the old linux system). 

Hence now we have a newer version of the bootloader, running with the previous (older) linux system. Hence we have a software combination, that was not intended to run together, probably not tested during development, but potentially running on a field device.

This is the main concern of this question. Could this lead to trouble? Is there a mechanism in RAUC to prevent falling into this situation? (Maybe my question is more a conceptual question than a RAUC question).

Hope this made my thoughts more clear. Thanks for the discussion and cheers,
Martin
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