[U-Boot] [PATCH v3 0/5] env: Add support for environment files

[Simon Glass]

HI Wolfgang,

On Sat, Oct 26, 2013 at 1:26 PM, Wolfgang Denk <wd at denx.de> wrote:
> Dear Simon,
>
> In message <1382763563-1483-1-git-send-email-sjg at chromium.org> you wrote:
>> (Note that Wolfgang is looking at a way of adjusting the environment
>> within a U-Boot binary - this series could fit with that but aims to
>> improve the creation of the initial default environment).
>>
>> 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.
>
> I think we need to be very clear hear about what these patches are
> actually doing.  Many users might easily confise the default
> environment that gets statically built into the U-Boot binary (and
> that cannot be changed at runtime) with the working environment that
> gets saved to some persistent storage and is loaded when booting.
>
> This is especially important as there are boards where, depending on
> which state of the boot process you are in, one or the other mightbe
> in effect (there used to be boards, and probably still are, where full
> environment access was not possible in the SPL [or whatever it was
> named then], so you were using the default settings initially, and the
> real environment only later - which can be extremely confusing - just
> think of thigs like console baudrate settings etc.

Yes agreed, I will have a think about a better title.

>
>> This series adds 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 for that vendor).
>
> I understand these patches are trying to improve the way how we
> initialize the CONFIG_EXTRA_ENV_SETTINGS setting in the _default_
> environment _at build time_, right?  I feel this should be made
> really clear in both the Subject: and in the commit message.
>

Agreed.

>
> Hm...  what was your reason for stopping half-way?  Setting only
> CONFIG_EXTRA_ENV_SETTINGS this way seems inconsequent to me.  Why do
> we not initialize the whole default environment like this?

Well just this change has provide quite a bit of discussion - I'm
quite pleased I didn't go further!

>
>
>> The environment variables should be of the form "var=value". Values can
>> extend to multiple lines. See the README under 'Environment Variables:'
>> for more information and an example.
>
> I am afraid I dislike the current proposal - see comments to that
> patch.

See my reply there.

>
>> After discussion on the mailing list the .emv file was moved from
>> include/configs to board/. See here:
>
> ".emv"?  Guess this is a typo?
>
>> Another discussion was compatibility with the environment commands
>> 'env export -t' and 'env import -t'. This series permits these to be used
>> and the environment is exported and imported as expected. I have dropped
>
> I can't see how this would work - the examples given in yout README
> patch definitely cannot be imported using "env import -t", which is
> the reason why I dislike the proposed format.
>
We should probably continue discussion on the other thread. I think I
have addressed this now (with your suggestion to perhaps change the
format of 'env import -t').

Regards,
Simon