Sharing TF-A with multiple BSP

["Joshua Watt" <JPEWhacker@gmail.com>]

Continuing the outcome from a discussion that was on the OE-core mailing 
list, I've started converting some of the BSP layers I work on to use 
the trusted-firmware-a recipe from meta-arm as the canonical source of 
ATF instead of each of the implementing their own recipe. So far this 
has gone well except for one annoyance I've found: meta-arm has a layer 
dependency on meta-python, specifically for the optee recipe. Normally, 
this wouldn't be such a big deal, but in a ideal world there will now be 
a lot of BSP layers that depend on meta-arm to provide ATF, and it seems 
annoying to have to make all of those layers (transitively) depend on 
meta-python.

I can think of a few possible options:

1) Do nothing because no one other than me thinks this is a problem :)

2) Use BBFILES_DYNAMIC to make optee optional based on the presence of 
meta-python

3) Use PACKAGECONFIG to remove the python parts of optee (if that's even 
possible). They can be automatically added back if meta-python is 
present via BBFILES_DYNAMIC.

4) Remove the hard requirement of meta-python from meta-arm; it's only 
needed to build optee so the users can figure it out?


Anyone else have any ideas or thoughts?

Thanks,
Joshua Watt