[OE-core] [bitbake-devel] Keeping multiconfig config files in sync

[chris.laplante at agilent.com]

> From: Richard Purdie <richard.purdie at linuxfoundation.org>
> Sent: Thursday, September 26, 2019 4:53 PM
> 
> This has bugged me since we first created multiconfig. It was always
> intended we'd have configs you could reference. It turned out to be
> hard to code and we (well, I) decided to "come back to it". That hasn't
> happened yet.
> 
> I'd welcome proposals on how it could work (its harder than it first
> appears). It'd be good to check we do have a bug open for it too.

Hmm, I just tried moving my multiconfig directory from build/conf to the 
conf directory of an arbitrary layer, and it worked. I added 3 multiconfigs,
each with a different MACHINE set. Then I added an anonymous Python
func that just bb.warn'd out the machine. When I ran in parse-only mode,
it printed out 4 warnings (including one for the default config I guess), with
the machine different each time.

The BB manual says "The reason for this required file hierarchy is because the 
BBPATH variable is not constructed until the layers are parsed. Consequently, 
using the configuration file as a pre-configuration file is not possible unless it 
is located in the current working directory."

You actually fixed this limitation in 2017 when you reworked the server API 
(poky commits 62bd2e36 and 4602408c). 

So, happily, I think this is just a case of documentation that needs updating :) 

Chris