From mboxrd@z Thu Jan  1 00:00:00 1970
From: Panu Matilainen <pmatilai@redhat.com>
Subject: Re: [PATCH v2] mk: pass EXTRA_CFLAGS to AUTO_CPUFLAGS to
 enable local modifications
Date: Mon, 7 Dec 2015 10:33:24 +0200
Message-ID: <56654454.3040508@redhat.com>
References: <20151124085001.58817bf0@miho> <56614AE8.2010200@netinsight.net>
 <566167CC.3040303@6wind.com> <4623746.AUJoGgWqRB@xps13>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Cc: dev@dpdk.org
To: Thomas Monjalon <thomas.monjalon@6wind.com>,
 =?UTF-8?Q?Simon_K=c3=a5gstr=c3=b6m?= <simon.kagstrom@netinsight.net>
Return-path: <dev-bounces@dpdk.org>
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28])
 by dpdk.org (Postfix) with ESMTP id 717339582
 for <dev@dpdk.org>; Mon,  7 Dec 2015 09:33:28 +0100 (CET)
In-Reply-To: <4623746.AUJoGgWqRB@xps13>
List-Id: patches and discussions about DPDK <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>

On 12/04/2015 08:53 PM, Thomas Monjalon wrote:
>>>> We have encountered a CPU where the AES-NI instruction set is disabled
>>>> due to export restrictions. Since the build machine and target machine
>>>> is different, using -native configs doesn't work, and on this CPU, the
>>>> application refuses to run due to the AES CPU flags being amiss.
>>>>
>>>> The patch passes EXTRA_CFLAGS to the figure-out-cpu-flags helper,
>>>> which allows us to add -mno-aes to the compile flags and resolve this
>>>> problem.
>>>>
>>>> Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
>>
>> Acked-by: Olivier Matz <olivier.matz@6wind.com>
>
> Applied, thanks
>

This causes some complications on Fedora/RHEL due to fairly complex 
interactions with -Werror, -Wall and -Wformat-security mixup between 
upstream- and distro default compiler flags.

More specifically, when EXTRA_CFLAGS contains warning flag manipulation 
this patch can cause mismatch between other options that are okay 
elsewhere in dpdk make. A simple fix is to pass WERROR_FLAGS to 
AUTO_CPUFLAGS too to counter this, ie

diff --git a/mk/rte.cpuflags.mk b/mk/rte.cpuflags.mk
index c6bb8de..28f203b 100644
--- a/mk/rte.cpuflags.mk
+++ b/mk/rte.cpuflags.mk
@@ -33,7 +33,7 @@
  # used to set the RTE_CPUFLAG_* environment variables giving details
  # of what instruction sets the target cpu supports.

-AUTO_CPUFLAGS := $(shell $(CC) $(MACHINE_CFLAGS) $(EXTRA_CFLAGS) -dM -E 
- < /dev/null)
+AUTO_CPUFLAGS := $(shell $(CC) $(MACHINE_CFLAGS) $(WERROR_FLAGS) 
$(EXTRA_CFLAGS) -dM -E - < /dev/null)

  # adding flags to CPUFLAGS


I can send an official patch if this seems acceptable.

	- Panu -