[Buildroot] [PATCH 3/3] New <pkg>-update-last-config-fragment target in pkg-kconfig.mk

[Yann E. MORIN]

Thomas, Arnout, Marcel, All,

On 2018-08-15 14:04 +0200, Thomas Petazzoni spake thusly:
> On Wed, 15 Aug 2018 01:20:29 +0200, Arnout Vandecappelle wrote:
> > > Marcel, do you think you could rework your patch series to go in the
> > > direction of showing a diff rather than arbitrarily adjusting the last
> > > fragment ?  
> > 
> >  Note that the diff really applies to the last fragment only, in the sense that
> > if the last fragment is setting CONFIG_BAR, the "is unset" bit has to come after
> > it. I don't think there is a way to say anything sensible automatically except
> > for the last fragment.
> 
> Yes, the diff cannot be blindly applied to anything but the last
> fragment. But the idea in showing the diff is not for the user to apply
> it blindly, but rather to determine which parts of the diff should be
> reflected to each fragment.

Indeed, it is not to be considered to be a diff of any of the fragment,
but of the configuration *as a whole*.

That's why I initially did not write a full diff, but only the delta
snippet, not the context, because it is a diff, not a patch.

But I think we should instead use the scripts/diffconfig script that is
in the linux kernel tree, and which outputs looks like:

    $ cat config.000
    CONFIG_FOO=y
    $ cat config.001
    CONFIG_FOO is not set
    $ ./scripts/diffconfig config.000 config.001
     FOO y -> n

which IMNSHO is exactly the message we want to convey.

Regards,
Yann E. MORIN.

> Best regards,
> 
> Thomas
> -- 
> Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
> Embedded Linux and Kernel engineering
> https://bootlin.com

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