envfs: provide an intentional way to ignore an existing external environment

[Michael Olbrich]

On Thu, Jul 31, 2014 at 09:44:16AM +0200, Uwe Kleine-König wrote:
> On Thu, Jul 31, 2014 at 09:33:02AM +0200, Juergen Borleis wrote:
> > On Thursday 31 July 2014 09:14:25 Uwe Kleine-König wrote:
> > > [...]
> > > Compared with storing the default environment in the external store the
> > > only difference is that you don't need to modify it if you change the
> > > internal one, right?
> > 
> > This would also be an advantage of this new feature.
> The only one even?
> 
> > > I wonder what the targeted use case is.
> > 
> > To use an external stored environment *only* for development purposes or tests 
> > and to keep the possibility to do so.
> Doesn't make a warm and cosy feeling. Isn't it easier and more robust to
> just not tell barebox about the external storage at all and for the
> testing/development procedure do an explicit
> 
> 	loadenv /dev/tralala

That doesn't help at all. There are several changes that I regularly use
that are required when init runs, so a manual loadenv is too late:
- global.autoboot_timeout=3 (the build-in value is 0 to boot faster by
  default).
- nfs automounts that contain '$user'

Also, this requires me to know _where_ the environment is. And that is not
easy to remember when I need to work with multiple devices a day and gets
worse, when it changes with the boot source (SD/eMMC). Mistakes are
guaranteed.

Michael

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