Re: [PATCH 2/2] Nokia RX-51: Remove CONFIG_PREBOOT from defconfig

[Tom Rini <trini@konsulko.com>]

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On Wed, Jul 27, 2022 at 09:01:15PM +0200, Pali Rohár wrote:
> On Wednesday 27 July 2022 14:58:20 Tom Rini wrote:
> > On Wed, Jul 27, 2022 at 08:52:01PM +0200, Pali Rohár wrote:
> > > On Wednesday 27 July 2022 14:48:23 Tom Rini wrote:
> > > > On Wed, Jul 27, 2022 at 08:34:41PM +0200, Pali Rohár wrote:
> > > > > On Monday 25 July 2022 17:21:00 Tom Rini wrote:
> > > > > > On Sun, Jul 10, 2022 at 01:42:56PM +0200, Pali Rohár wrote:
> > > > > > 
> > > > > > > CONFIG_PREBOOT just cause putting "preboot=CONFIG_PREBOOT" into env list.
> > > > > > > Value CONFIG_PREBOOT="run preboot" in defconfig is just nonsense and does
> > > > > > > not do anything useful (it is infinite recursion). Config file for this
> > > > > > > board already contains default preboot= env variable with correct value,
> > > > > > > which has higher priority than CONFIG_PREBOOT and this is reason why
> > > > > > > nonsense CONFIG_PREBOOT is ignored.
> > > > > > > 
> > > > > > > Remove nonsense and unused CONFIG_PREBOOT from nokia_rx51_defconfig file.
> > > > > > > 
> > > > > > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > > > > 
> > > > > > Applied to u-boot/master, thanks!
> > > > > 
> > > > > Patch 1/2 is missing.
> > > > 
> > > > Sorry if I was unclear enough in the rest of the emails, I'm not
> > > > applying 1/2.  The empty string is fine enough (again, other variables
> > > > have this issue).  Unless I missed something and there's a run-time
> > > > failure that 1/2 resolves?
> > > 
> > > The issue is that preboot= variable is defined in ENV array two times.
> > > Once in Kconfig and second time in regular environment define.
> > > 
> > > It is just coincidence that the definition from Kconfig is ignored
> > > because currently it is put _after_ the regular preboot= definition. But
> > > this is fragile and probably some unrelated change/patch could change
> > > this behavior.
> > > 
> > > We really do not want two preboot= definitions in ENV array and pray
> > > that the correct one would be used by U-Boot at runtime.
> > 
> > It's not coincidence, it's down to link order.  So it's not going to
> > break anytime soon.  And it's not just preboot that's in this situation.
> 
> It is not linker order, but rather order in which are specified
> preprocessor macros...

Ah right, sorry, I was thinking of something else I found when doing
CONFIG_EXTRA_ENV_TEXT / CONFIG_EXTRA_ENV_SETTINGS stuff.

> And what else is in the same situation as preboot? I just do not see
> other variable which is defined two times.

Right so it's all from include/env_default.h yes?  CONFIG_EXTRA_ENV_TEXT
and then CONFIG_EXTRA_ENV_SETTINGS win.  And pretty much everything else
in that file that has a CONFIG knob to it either has a different bit of
Kconfig "fun" to avoid the situation PREBOOT has or is already in the
same boat.

> > A more generic approach to deal with this would be appreciated.

Which is why I said this.  How we're doing this right now isn't great
and isn't super user friendly.  I don't want to have to repeat the logic
you do in 1/2 for all of the CONFIG options in env_default.h that aren't
already converted to Kconfig.

-- 
Tom

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