Board specific environments and broken configs

[Trent Piepho]

I wanted to add some additional commands to the env for a new board.
The barebox docs have this:

The default environment is composed from different directories during
compilation:
defaultenv/....
...
arch/$ARCH/boards/<board>/env       -> board specific overlay

Which made me think that putting an "env" directory in the board
directory would automatically add it to the environment.  It seemed
like a few boards I looked at did this and nothing more.  But no, this
does not work.

I see two ways to add extra env.  One is to reference a path in
CONFIG_DEFAULT_ENVIRONMENT_PATH.  The other is to add a path to
bbenv-y in the board's Makefile and then defaultenv_append_directory()
that linked in data in the board code.

But it seems like some boards do neither!  How do they work?  AFAICT,
the answer is they don't work.

I tried to do an exhaustive survey of board envs.  I found 98 env
directories used by 95 boards.  57 of those boards use a manual
defaultenv_append_directory().  There are 39 env directories not added
this way (efika-mx-smartbook has two env dirs, one in the makefile and
one not, thus 57 + 39 - 1 = 95).

Of the 39 env dirs not added in board code, 27 are referenced in a
defconfig file in CONFIG_DEFAULT_ENVIRONMENT_PATH.

And thus 12 env dirs appear to have no use in barebox.  delphi-poc20
appears to not even be a board, having just an env file, no code, no
references I could, and added in a commit for another board.  Mistake?

The 12 boards with apparently unused envs:
chumby_falconwing
crystalfontz-cfa10036
datamodul-edm-qmx6
delphi-poc20
dss11
efika-mx-smartbook
generic
karo-tx25
karo-tx51
mx31moboard
skov-imx6
technexion-wandboard

An issue with CONFIG_DEFAULT_ENVIRONMENT_PATH is that it applies to
all boards in a config.  If multiple boards are built at once, e.g.
imx_v7_defconfig, then there is no way for each board to have a
different extra env this way.