[U-Boot] U-boot env variables parsing

[Detlev Zundel]

Hi Jocke,

>> > > Hm... will this not make escaping impossible? Assume you want to pass
>> > >
>> > >    arg=${name}
>> > >
>> > > to Linux. How would you escape this so it does NOT get expanded if
>> > > you run process_macros() arbitrarily often?
>> >
>> > Possibly, I never needed that though.
>> > One would probably need to add an escape char for that. Something
>> > like arg=\${name}
>>
>> Woudn't this then just cause another cycle through process_macros(),
>> where it then gets substitured anyway? [Guess I gotta try this out.]
>
> I am not sure what will happen, it was so man years ago.
> But I would guess that if you really want to pass arg=$(name)
> to the kernel you will probably need to do some adjustment.

To me it looks like the new code would indeed do a "greedy" substitution
only stopping when no more substitutions can be done.  This is very
un-unixy and thus not something I'd like to see as a default behaviour.

When we want to move in this direction, then we should implement
something with finer control over the substitution rounds.

Cheers and happy easter all around
  Detlev

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