[dpdk-dev] mk: fix lib filtering

  I get the following error when linking the test application:
  build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
  In function `nicvf_qsize_regbit':
  drivers/net/thunderx/base/nicvf_hw.c:451: undefined reference to `log2'
  build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
  In function `nicvf_rss_reta_update':
  drivers/net/thunderx/base/nicvf_hw.c:804: undefined reference to `log2'
  build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
  In function `nicvf_rss_reta_query':
  drivers/net/thunderx/base/nicvf_hw.c:825: undefined reference to `log2'

While I don't know why it does not happen for a default build, the error
can be explained. The link command line is:

   gcc -o test ... *.o ... -Wl,-lm ... -Wl,-lrte_pmd_thunderx_nicvf ...

rte_pmd_thunderx_nicvf needs the math library, and it should be
added after. This is not the case because the test application also
adds the math library.

The makefile already filters the libraries, but it keeps the first
occurrence of the lib. Instead, the last one should be kept.

Fixes: edf4d331dcdb ("mk: eliminate duplicates from libraries list")

Cc: stable@dpdk.org
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 mk/rte.app.mk | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)
  

2017-04-06 16:14, Olivier Matz:
> I get the following error when linking the test application:
>   build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
>   In function `nicvf_qsize_regbit':
>   drivers/net/thunderx/base/nicvf_hw.c:451: undefined reference to `log2'
>   build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
>   In function `nicvf_rss_reta_update':
>   drivers/net/thunderx/base/nicvf_hw.c:804: undefined reference to `log2'
>   build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
>   In function `nicvf_rss_reta_query':
>   drivers/net/thunderx/base/nicvf_hw.c:825: undefined reference to `log2'
> 
> While I don't know why it does not happen for a default build, the error
> can be explained. The link command line is:
> 
>    gcc -o test ... *.o ... -Wl,-lm ... -Wl,-lrte_pmd_thunderx_nicvf ...
> 
> rte_pmd_thunderx_nicvf needs the math library, and it should be
> added after. This is not the case because the test application also
> adds the math library.
> 
> The makefile already filters the libraries, but it keeps the first
> occurrence of the lib. Instead, the last one should be kept.
> 
> Fixes: edf4d331dcdb ("mk: eliminate duplicates from libraries list")
> 
> Cc: stable@dpdk.org
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>

Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>

It is a really nice Makefile recursive function :)

> +# all the words except the first one
> +allbutfirst = $(wordlist 2,$(words $(1)),$(1))
> +
> +# Eliminate duplicates without sorting, only keep the last occurrence
> +filter-libs = \
> +	$(if $(1),$(strip\
> +		$(if \
> +			$(and \
> +				$(filter $(firstword $(1)),$(call allbutfirst,$(1))),\
> +				$(filter -l%,$(firstword $(1)))),\
> +			,\
> +			$(firstword $(1))) \
> +		$(call filter-libs,$(call allbutfirst,$(1)))))
> +
> +LDLIBS := $(call filter-libs,$(LDLIBS))

Applied, thanks
  

On Thu, Apr 06, 2017 at 04:48:11PM +0200, Thomas Monjalon wrote:
> 2017-04-06 16:14, Olivier Matz:
> > I get the following error when linking the test application:
> >   build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
> >   In function `nicvf_qsize_regbit':
> >   drivers/net/thunderx/base/nicvf_hw.c:451: undefined reference to `log2'
> >   build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
> >   In function `nicvf_rss_reta_update':
> >   drivers/net/thunderx/base/nicvf_hw.c:804: undefined reference to `log2'
> >   build/lib/librte_pmd_thunderx_nicvf.a(nicvf_hw.o):
> >   In function `nicvf_rss_reta_query':
> >   drivers/net/thunderx/base/nicvf_hw.c:825: undefined reference to `log2'
> > 
> > While I don't know why it does not happen for a default build, the error
> > can be explained. The link command line is:
> > 
> >    gcc -o test ... *.o ... -Wl,-lm ... -Wl,-lrte_pmd_thunderx_nicvf ...
> > 
> > rte_pmd_thunderx_nicvf needs the math library, and it should be
> > added after. This is not the case because the test application also
> > adds the math library.
> > 
> > The makefile already filters the libraries, but it keeps the first
> > occurrence of the lib. Instead, the last one should be kept.
> > 
> > Fixes: edf4d331dcdb ("mk: eliminate duplicates from libraries list")
> > 
> > Cc: stable@dpdk.org
> > Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> 
> Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>
> 
> It is a really nice Makefile recursive function :)
> 

"nice Makefile recursive function"

I recognise those words individually, but having them together just
doesn't make any sense :-)
  

2017-04-06 17:20, Bruce Richardson:
> On Thu, Apr 06, 2017 at 04:48:11PM +0200, Thomas Monjalon wrote:
> > It is a really nice Makefile recursive function :)
> 
> "nice Makefile recursive function"
> 
> I recognise those words individually, but having them together just
> doesn't make any sense :-)

Thanks for your attention :)