[U-Boot] [PATCH] env: Add CONFIG_ENV_SUPPORT

[Wolfgang Denk]

Dear Patrick,

In message <9c7801afb8c94c638933cf33746ae300 at SFHDAG6NODE3.st.com> you wrote:
> 
> And I agree the name seens not perfect.
> 
> > > - CONFIG_SPL_ENV_SUPPORT for SPL
> > > - CONFIG_TPL_ENV_SUPPORT for TPL
> 
> These pre-existing name are defined in common/spl/Kconfig
> 
> With the same issue (env/common.o env/env.o are always compiled for SPL/TPL
> so it is alo bad names)

Correct.

> > So please reconsider this whole implementation, and make sure that only a single
> > macro ise used everywhere to enable these features.
> 
> But, if I use the same CONFIG for the 3 binary SPL,TPL and U-Boot,
> l increase the size of TPL/SPL for all the platforms when these
> additional features are not needed.

Either the U-Boot environment makes use of these features, then they
have to be enabled, and exactly the same way in SPL, TPL and U-Boot
proper.  Or you don't need them, then they can be disabled, but
again in a consistent way in SPL, TPL, and U-Boot proper.

It is not acceptable to have for example .flags support in U-Boot,
but not is SPL.  If you cannot affort the size in SPL (and need
environment there at all), then you cannot have it in U-Boot either.
Yes, this is sad, but anything else would break the implementation of
these features, and given that they are often used to implement some
level of protection or security, introduce massive security issues.


So if SPL size is critical, you can try do not access the
environment at all and omit _all_ of the environment code there; or
you can try to arrange for a read-only implementation (omitting at
least the code needed for "env save" including write routines to
storage).  But you CANNOT omit the extensions if these are present
in U-Boot proper.

Best regards,

Wolfgang Denk

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