RFC: Support for U-Boot phases in Kconfig

[Sean Anderson]

On 8/11/21 10:17 AM, Tom Rini wrote:
> On Wed, Aug 11, 2021 at 08:03:00AM -0600, Simon Glass wrote:
>> Hi Tom,
>>
>> On Wed, 11 Aug 2021 at 07:47, Tom Rini <trini at konsulko.com> wrote:
>> >
>> > On Wed, Aug 11, 2021 at 06:56:31AM -0600, Simon Glass wrote:
>> > > Hi Tom,
>> > >
>> > > On Tue, 10 Aug 2021 at 13:38, Tom Rini <trini at konsulko.com> wrote:
>> > [snip]
>> > > > I need to take another pass at converting a bunch of symbols, to see
>> > > > where we're at.  Probably the biggest chunk of progress next would be to
>> > > > start converting CONFIG_SYS_xxx to SYS_xxx and moving defines out of
>> > > > config.h and in to something else.  I'm taking a peek at some of the
>> > > > remaining PCI ones now.
>> > >
>> > > How about we set a deadline for this? It has gone on for too long and
>> > > we just need to drop these CONFIGs. It's probably a higher priority
>> > > than a Kconfig change.
>> > >
>> > > I was expecting that the config.h files would go away and we would use
>> > > Kconfig (or DT) for everything. What sort of things don't fit into
>> > > that model?
>> >
>> > Environment is the hard one to move out from config.h and in to, well, I
>>
>> Well you know my views on that :-)
>>
>> http://patchwork.ozlabs.org/project/uboot/patch/1382763695-2849-4-git-send-email-sjg@chromium.org/
>>
>> I still think it makes more sense than #defines and I can resurrect
>> that series if you like.

This would be nice. I was thinking about doing something like this for
LIL, to make writing tests easier.

> That might work, yeah.  I just also want to focus on less things in
> progress at once.  That too I think has been part of why everything is
> taking so long.
>
>> > don't know what.  I think there's also a handful of symbols like
>> > CONFIG_SPL_MAX_SIZE that are a little tricky to convert directly (they
>> > do math based on other symbols) rather than just as evaluate-and-set.
>>
>> We can either evaluate them and put the answer in as the defconfig
>> value...or perhaps ask Masahiro to support evaluation in kconfig?!
>
> I do forget what kind of operations are allowed in Kconfig at this
> point, it might be possible now, yes.  And if not, something worth
> trying.

At the moment there are conditionals for dependencies and defaults [1].
It doesn't seem like too much of a stretch to allow for arbitrary
arithmetic. In particular, we could really get 80% of the functionality
with just + (and perhaps & or |).

https://www.kernel.org/doc/html/latest/kbuild/kconfig-language.html#menu-dependencies

--Sean