Locking down U-Boot env with ENV_WRITEABLE_LIST

[Tim Harvey]

On Sat, Apr 3, 2021 at 12:09 PM Marek Vasut <marex at denx.de> wrote:
>
> On 4/3/21 6:43 PM, Tim Harvey wrote:
>
> Hi,
>
> [...]
>
> >>>> And those config options I had enabled in u-boot defconfig:
> >>>>
> >>>> CONFIG_CMD_ENV_CALLBACK=y
> >>>> CONFIG_CMD_ENV_FLAGS=y
> >>>> CONFIG_ENV_IS_NOWHERE=y
> >>>> CONFIG_ENV_IS_IN_MMC=y
> >>>> CONFIG_ENV_APPEND=y
> >>>> CONFIG_ENV_WRITEABLE_LIST=y
> >>>> CONFIG_ENV_ACCESS_IGNORE_FORCE=y
> >>>
> >>> Do you really define both ENV_IS_NOWHERE and ENV_IS_IN_MMC? From what
> >>> I see if you define ENV_IS_NOWHERE none of the others will be used.
> >>
> >> Yes, having two ENV drivers is mandatory. One provides the base env (the
> >> nowhere) and the other is used to import the filtered extras from
> >> external env.
> >
> > Enabling ENV_IS_NOWHERE does not work as you describe in my testing.
> > I'm testing this with imx8mm_venice_defconfig on U-Boot 2021.01 and as
> > soon as I define ENV_IS_NOWHERE then env_load is never called because
> > when env_relocate is called env is not valid yet so env_set_default is
> > called and env_load is 'never' called, thus mmc env is never loaded.
> > This is all from
> > https://elixir.bootlin.com/u-boot/v2021.01/source/env/common.c#L259
>
> Maybe this [PATCH V3] env: Fix invalid env handling in env_init() patch
> is missing ?
>
> [...]
>
> >   /* Link Definitions */
> >   #define CONFIG_LOADADDR                        0x40480000
> >   #define CONFIG_SYS_LOAD_ADDR           CONFIG_LOADADDR''
> >
> > With this configuration a blank env in flash results in the entire
> > default env showing in an 'env print' (ie all the stuff from
> > include/env_default.h 'default_environment') but as soon as I put an
> > env in flash (ie saveenv) and reset now the only env is what was set
> > via running code (ethaddr's fdtcontroladdr stdin/err/out). The only
> > different I expected is that I expected the default env from
> > include/env_default.h to be there on an initial boot with no valid mmc
> > env.
>
> Maybe the aforementioned patch is missing ?

Marek,

Yes, that patch fixes the issue I'm seeing of mmc not initializing and
now the default env shows up as expected when MMC env is empty or
populated.

Thanks - hopefully that patch gets merged soon... I did respond with a
Tested-By.

Tim