Re: [dpdk-dev] [PATCH] port: fix build when KNI support is not enabled

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Jun 22, 2016 at 05:32:37PM +0200, Olivier Matz wrote:
> On 06/22/2016 02:20 PM, Thomas Monjalon wrote:
> > 2016-06-22 13:57, Olivier Matz:
> >> Hi Thomas,
> >>
> >> On 06/22/2016 01:49 PM, Thomas Monjalon wrote:
> >>> 2016-06-22 14:34, Panu Matilainen:
> >>>> --- a/lib/librte_port/Makefile
> >>>> +++ b/lib/librte_port/Makefile
> >>>> @@ -82,6 +82,8 @@ DEPDIRS-$(CONFIG_RTE_LIBRTE_PORT) += lib/librte_mempool
> >>>>  DEPDIRS-$(CONFIG_RTE_LIBRTE_PORT) += lib/librte_ether
> >>>>  DEPDIRS-$(CONFIG_RTE_LIBRTE_PORT) += lib/librte_ip_frag
> >>>>  DEPDIRS-$(CONFIG_RTE_LIBRTE_PORT) += lib/librte_sched
> >>>> +ifeq ($(CONFIG_RTE_LIBRTE_KNI),y)
> >>>>  DEPDIRS-$(CONFIG_RTE_LIBRTE_PORT) += lib/librte_kni
> >>>> +endif
> >>>
> >>> I do not remember why $(CONFIG_RTE_LIBRTE_PORT) is needed in its Makefile.
> >>> I think we can do
> >>> 	DEPDIRS-$(CONFIG_RTE_LIBRTE_KNI) += lib/librte_kni
> >>> and set DEPDIRS-y everywhere else.
> >>>
> >>
> >> It's probably not much used, but the build framework allows to do
> >> the following to build only one directory:
> >>
> >>   make lib/librte_port_sub
> >>
> >> This directly jumps to the librte_port Makefile, bypassing parent
> >> directories. I think that's why the config check is duplicated in the
> >> Makefile.
> > 
> > If we want to specifically build this directory, why preventing us to do
> > so with CONFIG_RTE_LIBRTE_PORT?
> 
> If we call foo_sub with CONFIG_FOO=n, it will generate a library and
> install headers in the build directory, however the config is unset.
> Some propositions if we want to replace
> DEPDIRS-$(CONFIG_RTE_LIBRTE_PORT) by DEPDIRS-y:
> 
> 1/ say that "make foo_sub" should be used with care, only if CONFIG_FOO
>    is set (else it is not supported) -> nothing to do
> 2/ fix the make %_sub feature to browse parent directories, checking
>    the SUBDIRS-${CONFIG_FOO}
> 3/ remove the make %_sub feature, maybe nobody cares...
> 
> I think 1/ is acceptable.

+1

Especially given the fact I wasn't even aware that you could do that (building
just one subdir). Do we have a usecase where people might want to build just one
DPDK subdirectory?

/Bruce