[U-Boot] [PATCH] Add support for setting environment variable from RAM.

[Eric Nelson]

Wolfgang Denk wrote:
> Dear Eric,
> 
> In message <4988936E.3070504 at boundarydevices.com> you wrote:
>>> In the email thread you mentioned above, Detlev mentions 2 alternatives
>>> to the "ramenv" command - loading a uImage script and running it via
>>> autoscr, or modifying autoscr to be able to raw files (non-uImages).
>>> Both of these methods seem cleaner and more flexible at a glance.  Is
>>> there a specific reason using autoscr wouldn't work for your setup?
>>>
>> The customer requesting this feature operates in a regulated environment with
>> pretty strict rules about separation of code and data. Autoscr is kind of
>> a big stick for what we're trying to achieve: (configuring an LCD with
>> settings from a file on SD card).
> 
> Why is it a big stick? It has a couple of significant advantages over
> your implementation:
> 
No offense intended ;) Perhaps I should have said it was a much more powerful feature.

> * It already exissts in mainline.
> * It can set several environment variables at once (and also perform
>   any other commands you might need on your system).
> * It is based on text files which are easy to edit without need for
>   new tools.
> * It will verify that your file has been transmitted correctly.
> 
Don't get me wrong, I'm a big fan of autoscr.

As I mentioned, the customer requesting the feature has a regulatory
requirement any time __code__ changes. They have interpreted boot loader
scripts as being executable, so they have to write checks if the script
changes, but not if "data" changes. They interpret a file containing a
variable as data.

Of course they'll need a code release to get there, ...

>> Our particular need is just for a single environment variable, so the
>> update works pretty well. I started by updating our 'lcdpanel' U-Boot
>> command to read from file, but this is much more useful.
> 
> I suggest you use autoscr instead.
> 
> I think I will reject your patch.
> 
That's reasonable. I don't mind carrying the patch around for this customer,
and you're the one preventing U-Boot from becoming bloated over time.

I appreciate all of your efforts.

Regards,


Eric