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 Tue, 2025-01-14 at 10:38 -0500, Brian Hutchinson via RAUC wrote:
> On Mon, Dec 9, 2024 at 3:43 AM Jan Lübbe <jlu@pengutronix.de> wrote:
> > 
> > Hi again,
> > 
> > On Thu, 2024-12-05 at 22:38 -0500, Brian Hutchinson via RAUC wrote:
> > > This almost feels like the intermediate update that's necessary with
> > > changing rauc versions ...
> > 
> > Enrico pointed me to this part.
> > 
> > Updating RAUC versions normally does *not* require an intermediate
> > update. An intermediate update is only needed if you explicitly create
> > bundles which use new features:
> > https://rauc.readthedocs.io/en/latest/basic.html#forward-and-backward-compatibility
> 
> Thanks!
> 
> I should probably start another thread, but now I'm running into a
> chicken & egg problem.
> 
> I need to add downgrade protection due to newer hardware

Just to clarify: You want to prevent installation of an old bundle on the new
hardware, as the old software would not work on the new hardware?

> and I
> discovered pre-install handler doesn't have access to bundle version
> (RAUC_MF_VERSION), only a hook has that environment variable.  Well,
> if I create a hook that can compare bundle version to current version
> to do some hardware checks ... that hook won't be in older bundles, so
> wondering how pre-install handler (which lives in the current version
> file system) can figure out the bundle version attempting to be
> installed if it can't see RAUC_MF_VERSION to implement downgrade
> protection if that makes any sense.

Take a look at the "min-bundle-version" option in the system.conf:
https://rauc.readthedocs.io/en/latest/reference.html#system-section 

You'd set that in the factory image of your new hardware. That way, old bundles
cannot be installed.

Regards,
Jan
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