From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas.monjalon@6wind.com>
Subject: Re: [PATCH] mk: fix lib filtering
Date: Thu, 06 Apr 2017 16:48:11 +0200
Message-ID: <497164429.X1217vCfaY@xps13>
References: <20170406141455.14894-1-olivier.matz@6wind.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7Bit
Cc: dev@dpdk.org, stable@dpdk.org
To: Olivier Matz <olivier.matz@6wind.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-wr0-f178.google.com (mail-wr0-f178.google.com
 [209.85.128.178]) by dpdk.org (Postfix) with ESMTP id 1EA182B84
 for <dev@dpdk.org>; Thu,  6 Apr 2017 16:48:15 +0200 (CEST)
Received: by mail-wr0-f178.google.com with SMTP id w11so60568292wrc.3
 for <dev@dpdk.org>; Thu, 06 Apr 2017 07:48:15 -0700 (PDT)
In-Reply-To: <20170406141455.14894-1-olivier.matz@6wind.com>
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

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