[U-Boot] [PATCH v2 3/5] Allow U-Boot scripts to be placed in a .env file

[Stephen Warren <swarren@wwwdotorg.org>]

On 10/20/2013 09:47 PM, Simon Glass wrote:
> Hi Stephen,
> 
> On Wed, Jun 26, 2013 at 1:56 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 06/24/2013 02:46 PM, Simon Glass wrote:
>>> At present U-Boot environment variables, and thus scripts, are defined
>>> by CONFIG_EXTRA_ENV_SETTINGS. It is painful to add large amounts of text
>>> to this file and dealing with quoting and newlines is harder than it
>>> should be. It would be better if we could just type the script into a
>>> text file and have it included by U-Boot.
>>>
>>> Add a feature that brings in a .env file associated with the board
>>> config, if present. To use it, create a file in a board/<vendor>/env
>>> directory called <board>.env (or common.env if you want the same
>>> environment for all boards).
> 
> [well perhaps it is time to get back to this]
> 
>> I'm not entirely sure how useful common.env is.
>>
>> Consider that many different Tegra boards, from different vendors, all
>> share the same environment. For example boards/compulab/trimslice shares
>> the core environment with boards/nvidia/*. IIUC, common.env wouldn't
>> work in this case, since the vendor is different. To solve that, we
>> could easily symlink board/compulab/env/trimslice.env ->
>> board/nvidia/env/something.env. But in that case, why not always rely on
>> creating symlinks, instead of having the common.env fallback work too?
>> Also consider that compulab makes a ton of boards only some of which use
>> Tegra, so even a common.env in board/compulab/env wouldn't be that useful.
> 
> I find symlinks a pain in the source tree. I think they should be the
> exception rather than the rule. This feature here mirrors the current
> board/<vendor>/common directory which is fairly widely used.

Well, we use includes rather than symlinks, e.g. put the following into
boards/compulab/env/trimslice.env:

#include <boards/nvidia/env/something.env>

> $ ls board/*/common -d |wc -l
> 21
> 
> I feel that Compulab can do their own common file if they want it

I'd rather as many board worked the same way as possible; that makes it
much easier for distros, and even developers. We shouldn't go out of our
way to make that hard.

> A file common to all Tegra perhaps belongs in arch/arm/.. somewhere?

That might be a better location, yes.