Re: [PATCH -next 2/2] kbuild: fix for updated LZ4 tool with the new streaming format

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Andrew, All,

On Thursday 18 July 2013 09:34:08 Andrew Morton wrote:
> On Thu, 18 Jul 2013 09:22:58 +0200 Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Thu, Jul 18, 2013 at 12:30 AM, Yann E. MORIN <yann.morin.1998@free.fr> wrote:
> > > On 2013-07-17 23:16 +0200, Sam Ravnborg spake thusly:
> > >> > We could extend the symbol option part to retreive values from a binary.
> > >> > Something like this:
> > >> >
> > >> > config FOOBAR
> > >> >         bool
> > >> >         option exec="true"
> > >> >
> > >> > FOOBAR would assume the value "y" if the command true has exit code == 0, otherwise "n".
> > >> > And similar conversions for other types.
> > >> >
> > >> > This only extendt Kconfig slightly - using an already present method to import
> > >> > external values.
> > >> Following is a quick patch implmenting this idea.
> > >> You need to run gperf manually to enable this.
> > >>
> > >> "gperf -C scripts/kconfig/zconf.gperf > scripts/kconfig/zconf.hash.c"
> > >>
> > >> I did not figure out how to use the built-in rules to generate this file :-(
> > >
> > > make REGENERATE_PARSERS=y menuconfig
> > >
> > >> I have tested this lightly - as we should discuss if this is a viable way forward.
> > >
> > > Instead of extending the Kconfig language, I was thinking (as initially
> > > suggested by Andrew) of generating a Kconfig file before all config
> > > targets, and source that Kconfig file from $(TOPDIR)/Kconfig.
> > 
> > I also prefer the generated Kconfig file.
> > It keeps all these checks in a single place, instead of spreading it over all
> > Kconfig files. This allows to keep better control over the list of checks, and
> > notice when it gets out-of-hand.
> 
> I prefer the "option exec" approach, actually.  That way the shell-outs
> are colocated with the code which uses

Indeed, but in this case, all the checks will be spread-out in the Kconfig
files, and not easily locatable. Having all in a single script will also
more easily raise eyebrows when that script appears in a diffstat. Noticing
the 'exec' option risks being a bit less easy.

But, that's not my call to decide. ;-)

> them and they will only be executed
> if you've actually selected that subsystem for building (I think?).

If I understand the code correctly (which is still to be proven), the
exec option is run at parse-time, once.

Regards,
Yann E. MORIN.

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