RFC: Add lookup for device specific files

[nbuchwitz]

This series implements / re-uses device specific file lookup for rpiboot. With this existing targets like recovery5 and recovery can be merged and thus simplify the user experience. Also during automated setups it helps as the abstraction is handled by rpiboot (we currently use this kind of automatism for having a unified recovery / firmware update procedure in production).

As example the recovery target is merged. mass-storage-gadget64 and secure-boot-recovery and be probably also merged.

Looking forward for thoughts about this approach

[timg236]

I'd prefer to keep the recovery targets separate. There are significant differences in the bootrom between 2711 and 2712

[nbuchwitz]

Yes, they still are (in 2711/ and 2712/ subfolders). The idea behind this is to use a single target, so it can be used with rpiboot -d recovery. For instance we have this running in some production tools, where the operator can connected cm4 / cm4s / cm5 based devices and rpiboot is automatically started via a udev rule (triggers systemd service). Without this patch it will need additional detection logic on the outside.

[timg236]

I think the chip-specific change is potentially useful but I don't think it's desirable to combine the recovery sub-directories.

[nbuchwitz]

Ok, with at least the functional changes in rpiboot I can work around this locally with symlinks for both recovery target to 2711/2712 in a new folder. I will will drop the merge commit.

[timg236]

Thanks. Let's get the functional change in first because I think that's the 'right' precedence anyway. I'll have another think about the recovery stuff.