[poky] Create a recovery partition

[Bas Mevissen]

On 2018-05-08 15:44, Andrea Previtali wrote:
> Hi everybody, I have little skills in Yocto. I need to realize a
> recovery partition on my system and I need to manage it in case my
> primary file system shows problems.
> I really have no idea where to start and I found no help on the
> internet.
> Has anybody faced out this problem?
> 
> Regards,
> Andrea

Hi Andrea,

The basics are that you:

1) Have a compact bootable image that contains just enough to recover 
the normal image. This system might share stuff like device tree file 
and kernel or have their own copy, depending on the update strategy.

2) Have a means in the bootloader to boot into this recovery system. For 
example, detect watchdog timeout or read some button status during boot 
(press and hold that button during power up to get into recovery mode). 
After successful recovery, the normal system can be booted again.

Some boards might also be able to boot from another boot source (e.g. 
sdcard) depending on some jumper setting or otherwise. You can use that 
feature to boot a recovery image and restore your normal image.


Hope this gives you a first start.

As this is not necessarily a Yocto/Poky specific issue, further 
discussion is better done off-list.

Cheers,

Bas.