[Buildroot] [PATCH 2/3] Add support for BR2_EXTERNAL

[Arnout Vandecappelle <arnout@mind.be>]

On 12/09/13 23:30, Ryan Barnett wrote:
> Arnout Vandecappelle <arnout@mind.be> wrote on 09/12/2013 04:05:18 PM:
>
>  > On 11/09/13 04:03, rjbarnet at rockwellcollins.com wrote:
>  > > Thomas Petazzoni <thomas.petazzoni@free-electrons.com> wrote on
>  > > 09/08/2013 08:15:28 AM:
>  > >
>  > >  >
>  > >  > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
>  > >  > ---
>  > >  >  Config.in   |  6 ++++--
>  > >  >  Makefile    | 29 +++++++++++++++++++++++++----
>  > >  >  docs/manual/manual.mk |  2 +-
>  > >
>  > > One idea that I have, is for the make file that is genreated for the an
>  > > external output directory, if we could preserve the the value of
>  > > BR2_EXTERNAL
>  > > as follows.
>  >
>  >   Thomas's patch already does that, because BR2_EXTERNAL is stored in the
>  > config file.
>  >
>
> I don't believe it gets stored in the config since Config.in pulls
> the variable in from the shell's or make's environment.
>
> +config BR2_EXTERNAL
> +       string
> +       option env="BR2_EXTERNAL"
>
> In order to utilize the BR2_EXTERNAL feature I must have BR2_EXTERNAL
> either exported into my environment or be called as

  The Makefile exports it in the environment of the Kconfig targets. So 
once it is in the .config, it will stay there. Try it and you'll see :-)

>
> 'make BR2_EXTERNAL=/some/path <target>'
>
>
> When utilizing the BR2_EXTERNAL I usual want to use some defconfig from
> my BR2_EXTERNAL so it adding it the makefile that is generated in your
> build directory when specifying O= would be extermely useful as that
> way I can switch shells and my definition of BR2_EXTERNAL would still
> be present.
>
> 'make O=/build/path BR2_EXTERNAL=/path/to/external defconfig'

  In this particular case, you're not using the Makefile in the output 
dir but only in the buildroot dir so it's not relevant.

  The only case where it would be relevant is when you have an existing 
output directory, you remove the .config first, and then you do a
make foo_defconfig. Seems a bit an unlikely scenario.

  Regards,
  Arnout

>
>  > > I don't think my logic is fully there but there is more of a
>  > > sudo implementation:
>  > >
>  > > diff --git a/support/scripts/mkmakefile b/support/scripts/mkmakefile
>  > > --- a/support/scripts/mkmakefile
>  > > +++ b/support/scripts/mkmakefile
>  > > @@ -27,6 +27,7 @@ makedir := \$(dir \$(call lastword,\$(MAKEFILE_LIST)))
>  > >
>  > >   MAKEARGS := -C $1
>  > >   MAKEARGS += O=\$(if \$(patsubst
>  > > /%,,\$(makedir)),\$(CURDIR)/)\$(patsubst %/,%,\$(makedir))
>  > > +MAKEARGS += BR2_EXTERNAL=\$(realpath \$(BR2_EXTERNAL))
>  > >
>  > >   MAKEFLAGS += --no-print-directory
>  > >
>  > > Again this is only a suggestion but otherwise I'll ack the patchset.
>  > >
>


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
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