Re: [RAUC] file slot type

[Enrico Joerns <ejo@pengutronix.de>]

Hi Leif,

On 05/09/2017 11:40 AM, Middelschulte, Leif wrote:
> Hi,
>
> I was wondering about the 'file' slot type.
>
> Though it's mentioned in the tests, `rauc bundle` complains about an invalid manifest.
>
> Entries like '[file.uctrl]' within the manifest lead to failure during compilation, while '[image.uctrl]' are accepted.
>
> Is it supposed to work at this point?

no, it is not.

The [file] entries seem to be a bit confusing, I agree with you. We just 
have a similar discussion on GitHub [1].

When starting with RAUC, we had two major operation modes in mind; 1) 
the one that became the standard one now with signed bundles that 
contain image artifacts and 2) a so-called 'network' operation mode that 
allows to download the manifest and the artifacts described in it 
separately from a server. This mode is rarely used and we plan to 
replace it with a network mode that works with streaming bundles over 
network.

Now, for the network mode aimed to use files instead of images as it 
targeted a setup with placing files in an existing file system instead 
of writing whole fs images.


To sum up: Using [file.slot/name] is not possible with bundle 
installations and migh also become obsolete for the old network 
installation mode.


But, in RAUC, everything you can describe as a path in your system could 
also be used as a slot for updating. Thus if you need to place (for 
whatever reason) files under a special path, you could simply make this 
path a slot:

   [slot.uctrl]
   device=/fs/path/to/your/uctrl.img
   ...

But also note that in most cases this is an unnecessary hack. You can 
simply place your uctrl code withing your rootfs that you update. This 
has the great advantage that you will not accidentally update a system 
with a uctrl image that is not tested to work properly with the rootfs 
installed on that system. Installing only well-tested combinations of 
software is an important building block for a robust update strategy!


Best regards

Enrico


[1] https://github.com/rauc/rauc/issues/114


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