[Buildroot] [PATCH 1/2] infra: improve dependency check in virtual packages.

[Arnout Vandecappelle <arnout@mind.be>]

On 25/02/14 13:04, Eric Le Bihan wrote:
> Hi!
> 
> On Mon, Feb 24, 2014 at 07:29:51PM +0100, Yann E. MORIN wrote:
> [...]
>> I don't know about you folks, but I'm beginning to see a pattern here...
>>
>> If all of our BR2_PACKAGE_HAS_FOOBAR options would match the corresponding
>> FOOBAR_DEPENDENCIES, then we could use something like (absolutely untested,
>> only pure random thoughts):
>>
>>     $(eval $(call virtual-package,FooBar))
>>
>> whith 'virtual-package' something like:
>>
>>     define virtual-package
>>     ifeq ($(BR2_PACKAGE_HAS_$(call upper,$(1))),y)
>>     ifeq ($($(call upper,$(1))_DEPENDENCIES),)
>>     $(error No $(1) implementation selected. Configuration error.)
>>     endif
>>     endif
>>     endef
>>
>> But then we would need:
>>     s/BR2_PACKAGE_HAS_OPENGL_EGL/BR2_PACKAGE_HAS_LIBEGL/
>>     s/BR2_PACKAGE_HAS_OPENGL_GLES/BR2_PACKAGE_HAS_LIBGLES/
>>     s/BR2_PACKAGE_HAS_OPENMAX/BR2_PACKAGE_HAS_LIBOPENMAX/
>>     s/BR2_PACKAGE_HAS_OPENVG/BR2_PACKAGE_HAS_LIBOPENVG/
> IMHO, renaming BR2_PACKAGE_HAS_OPENGL_GLES to BR2_PACKAGE_HAS_LIBGLES and
> friends is OK, as it matches the mesa3d naming and sounds less redundant.
>> Lua interpreter and PowerVR already match this.
>>
>> We could even go further, so as to only require a call to 'virtual-package'
>> and not to 'generic-package', with some carefully-crafted Makefile
>> constructs (but we would loose the capitalisation of eg. lbEGL, since the
>> package is named 'libegl', all in lower-case). 'virtual-package' could
>> even override FOOBAR_SOURCE="" before calling generic-package behind the
>> hood. This would make writing virtual packages even easier.

 Indeed, I alluded to this in my comments on one of the earlier versions
of Eric's patches.

 In fact, you don't need to do a $(generic-package) at all. Nothing of
the generic package infrastructure is needed for virtual packages: no
source fetching, no building and installing, no legal info, no nothing.
Therefore also the stamp files are redundant. Therefore also the build
directory is redundant. Therefore also the version is redundant.

 The only thing we need is:

$(pkg): $($(PKG)_DEPENDENCIES)

 We probably need a few more in order to propagate the other things that
need dependency chains, perhaps -source and -legal-info (though it looks
like that is still done through the TARGETS_SOURCE variable - I thought
we removed that at some point?).


>>
>> Thought?
> I like the idea. The virtual packages would become one-liners :-)
> I'll test it.

 Make sure you do this on top of -next, because it may be affected by
Fabio's parallel build changes.

 Regards,
 Arnout

> 
> Best regards,
> ELB
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> 


-- 
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
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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