[U-Boot] How to enforce saveenv at boot

[Stefano Babic]

Hi Mark,

On 05/04/19 13:13, Jonas Mark (BT-FIR/ENG1) wrote:
> Hi,
> 
> Our board stores the U-Boot environment in an MTD partition. I would like to
> ensure that there is always an U-Boot environment stored in MTD so that the
> userspace tool fw_setenv does not need to fall back on its built in default
> environment or a default environment stored in a file (see
> https://github.com/sbabic/libubootenv).
> 
> When U-Boot starts up it checks whether the specified MTD partition contains
> a valid environment and loads it. In case there is no valid environment it
> will use the compiled in default. Is there already a feature in U-Boot which
> would then also write that default to the MTD partition?
> 

As far as I know, there is not (yet ?) a way to expose to the shell if
the default environment is used, something like exporting gd->env_valid.

> Alternatively a Hush script could help. Is there an easy way to detect that
> U-Boot is using the compiled in environment? In that case I could simply do a
> saveenv (?) which would then initialize the MTD environment partition.

A trick (a hack ?) could be to have a variable in the default
environment and you check and delete it if exists, maybe in your "preboot".

if env_exists use_default;then setenv use_default;saveenv;fi

I do not know if there is a better way to do this.

Best regards,
Stefano


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