Howto implement bootchooser <-> rauc interaction

[Ahmad Fatoum]

On 16.12.21 20:35, Konstantin Kletschke wrote:
> On 2021-12-15 11:56, Ahmad Fatoum wrote:
> 
>> I think Roland meant that you shouldn't rely on the _mutable_ environment
>> for production. It's nice to test out stuff, but once you have figured
>> out what you need, add it to the built-in environment (e.g.
>> arch/arm/<board/myenv or CONFIG_DEFAULT_ENVIRONMENT_PATH).
> 
> Okay, then I got it - the intention of Roland. Compiled default environment
> is no problem.
> 
> But regarding required bootchooser variables: what of those are required?
> I said I utilised
> https://bootlin.com/blog/another-system-update-adventure-with-rauc-barebox-yocto-project/
> there is the barebox-state DT tree setup explained (a bit) and then it points out
> [...]Now we have to add bootchooser variables associated to both targets in arch/arm/<board>/env/nv[...]
> Which is rather abstract on how to do this, especially, if I have
> 
> bootstate.system0.remaining_attempts
> 
> in the DT, why should I replicate this in arch/arm/<board>/env/nv?

bootchooser variables are those that start with bootchooser.*. You named
your state bootstate in the device tree, thus the state driver creates
bootstate.* variables, which can be used to read/write the values.

You need to tell bootchooser which state to take via bootchooser.state_prefix,
but that's it. No need to mess direclty with the state variables.


> Or is there a connection needed to be created? Which variables need to be specified?
> Isn't it already there?
> 
>> > barebox at TI AM335x BeagleBone black:/ devinfo state
>> > Parameters:
>> > bootstate.last_chosen: 0 (type: uint32)
>> > bootstate.system0.ok: 0 (type: uint32)
>> > bootstate.system0.priority: 21 (type: uint32)
>> > bootstate.system0.remaining_attempts: 3 (type: uint32)
>> > bootstate.system1.ok: 0 (type: uint32)
>> > bootstate.system1.priority: 20 (type: uint32)
>> > bootstate.system1.remaining_attempts: 3 (type: uint32)
>> > dirty: 0 (type: bool)
>> > init_from_defaults: 0 (type: bool)
>> > save_on_shutdown: 1 (type: bool)

See https://elinux.org/images/9/9d/Barebox-bells-n-whistles.pdf Slide 26 for an example
/env/nv for a redundant boot setup.

> 
>> > Is bootchooser smart enough to gather system0 and system1 as bootable entries/possibilities?

You need to tell it what system0 and system1 are. See example linked above.

> 
>> > barebox at TI AM335x BeagleBone black:/ bootchooser
>> > ERROR: bootchooser: Target list $global.bootchooser.targets is empty
>> > No bootchooser found
> 
> May be this is my problem:

Ye. You need to tell bootchooser what boot targets there are.

>> hand is manageable, because you restrict what variables are available
>> and how they interact with the rest of the system.
> 
> ?
> 
> 
> What I mixed into my not so elaborated mail is a SIDE QUEST:
> 
> I can boot a bootloader spec equipped partitio like this:
> 
> barebox at TI AM335x BeagleBone black:/ boot mmc1.2
> 
> 
> How do I make a boot entry "system0" a boot.default variable can point to and also a member
> of bootchooser.targets?
> 
> I tried mmc1.2 or "boot mmc1.2" as system0 content but that did not work...

It's a two step thing. First you define your targets, e.g. system0 and system1
Then bootchooser knows the name of the state variables to consult and then
basically does boot ${global.bootchooser.system0.boot}.

Cheers,
Ahmad

> 
> 
> 
> 
> Kind Regards
> Konsti
> 
> 


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