[Buildroot] [RFCv1 0/4] Per-package SDK and target directories

[Arnout Vandecappelle]

On 07-11-17 18:13, Thomas Petazzoni wrote:
>> diff --git a/package/ccache/ccache.mk b/package/ccache/ccache.mk
>> index afbec44..66bfcad 100644
>> --- a/package/ccache/ccache.mk
>> +++ b/package/ccache/ccache.mk
>> @@ -50,6 +50,7 @@ BR_CCACHE_INITIAL_SETUP = $(call qstrip,$(BR2_CCACHE_INITIAL_SETUP))
>>  ifneq ($(BR_CCACHE_INITIAL_SETUP),)
>>  define HOST_CCACHE_DO_INITIAL_SETUP
>>      @$(call MESSAGE,"Applying initial settings")
>> +    rsync -au --link-dest=$(HOST_DIR) $(HOST_DIR) $(call qstrip,$(BR2_HOST_DIR))
>>      $(CCACHE) $(BR_CCACHE_INITIAL_SETUP)
>>      $(CCACHE) -s
>>  endef
> I don't think that's what we want. The global HOST_DIR (output/host)
> should basically be empty during the entire build process. Instead,
> what we want is to have the ccache host tools installed in the
> per-package SDK. This means that all packages have to have a dependency
> on host-ccache, which is not currently the case. So we probably instead
> want something like:
> 
> ifeq ($(BR2_CCACHE),y)
> $(2)_DEPENDENCIES += host-ccache
> endif
> 
> in package/pkg-generic.mk. But of course, we need to exclude the
> host-ccache package from this, otherwise we would have a circular
> dependency. Do you want to try something like this?

 Ha, I didn't understand the original problem but now I see. The issue is that
ccache is part of DEPENDENCIES_HOST_PREREQ, and DEPENDENCIES_HOST_PREREQ is
*not* added to each package's DEPENDENCIES, instead it is added to the
core-dependencies target and each package depends on that. It's an easy way to
avoid circular dependencies, I guess.

 So I think the proper solution would be to add DEPENDENCIES_HOST_PREREQ to the
dependencies of all packages except themselves, similar to how it's done for
toolchain.

 By the way there will also be a problem when host-tar is part of
DEPENDENCIES_HOST_PREREQ: ccache needs host-tar to be able to build, but there
is no explicit dependency between them, it relies purely on left-to-right order.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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