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

[Simon Glass]

Hi Tom,

On Tue, Apr 23, 2013 at 4:33 PM, Tom Rini <trini at ti.com> wrote:
> On Tue, Apr 23, 2013 at 02:32:00PM -0700, Simon Glass wrote:
>> Hi Wolfgang,
>>
>> On Tue, Apr 16, 2013 at 10:44 PM, Wolfgang Denk <wd at denx.de> wrote:
>> > Dear Simon Glass,
>> >
>> > In message <1366155414-6525-1-git-send-email-sjg at chromium.org> you 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 include/configs
>> >> with the same name as you could board config file, except with a
>> >> .env extension instead of a .h extension. The variables should be
>> >> separated by \0. Comments are permitted, using # as the first character
>> >> in a line.
>> >
>> > Please do not litter the include/configs/ directory with such stuff.
>> > It's more than big enough already.  Please put such files into the
>> > respective board directories.
>>
>> OK.
>>
>> >
>> > And if you do something like this, then please go the way to the end.
>> > Forget about the \0 termination, make it a plain text file instead,
>> > something that can be used with "env import -t" as well (or created
>> > with "env export -t").
>>
>> I'm not sure how to do this. Doesn't this mean that we cannot add
>> multi-line scripts to the environment? That was part of my aim. But if
>> I put a 0x0a in the script then it will think we are starting a new
>> variable.
>
> The first thing that pops to mind is:
> 1) embedded the text file into a linker-known spot
> 2) Make part of the default env setup process be to env import -t that
> location in memory.

Well I have a working implementation - my concern was more about how
to deal with newlines. I would like to be able to handle a script just
written out over multiple lines in a text file. This is really nice
because we can have proper indenting, comments, etc. As soon as we
have to use 0x0a as the separator between each environment variable
that is no longer possible.

My current scheme requires the .env file to have \0 separating
environment variables which is obviously not ideal. I am hoping we can
find another way which is more textfile-friendly without losing the
benefits.

Regards,
Simon

>
> --
> Tom