Re: [RAUC] Is it possible to change the [system]compatible= string after it has already been set/flashed?

["Jan Lübbe via RAUC" <rauc@pengutronix.de>]

On Thu, 2024-12-05 at 22:38 -0500, Brian Hutchinson via RAUC wrote:
> Hi,
> 
> Since it's common to produce boards with pre-programmed flash etc., is
> it possible to change the [system]compatible= string when hardware
> changes happen and the compatible string needs to be updated when it
> has already been set previously?
> 
> I know that hooks could be used to key in on bundle version
> information to implement things like downgrade barriers etc., but it
> just feels more elegant to update the compatible string to describe
> hardware changes that are human readable than to keep up with a eye
> chart truth table of version number combinations to determine what is
> safe to downgrade, upgrade etc.
> 
> I was thinking if maybe [system]variant-file was used in system.conf,
> then a pre-install hook could easily manipulate the compatible string,
> but not sure that would work.
> 
> This almost feels like the intermediate update that's necessary with
> changing rauc versions ... but I searched the mail archives and
> couldn't find anyone wondering about this sort of thing so thought I'd
> ask Jan, Enrico & Co. their thoughts.

You can use a 'install-check' hook [1] in the bundle to override the normal
compatible check. 

Also, the variant handling is built in a way so that you can start setting the
system variant in new systems that behave differently and you can target the
different images correctly.

Regards,
Jan

[1] https://rauc.readthedocs.io/en/latest/using.html#install-hooks

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