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Wed, 15 Sep 2021 21:23:19 GMT Received: from b01ledav001.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C4CFE28058; Wed, 15 Sep 2021 21:23:19 +0000 (GMT) Received: from b01ledav001.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A351828060; Wed, 15 Sep 2021 21:23:18 +0000 (GMT) Received: from Davids-MBP.randomparity.org (unknown [9.211.49.26]) by b01ledav001.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 15 Sep 2021 21:23:18 +0000 (GMT) To: Bruce Richardson , dev@dpdk.org Cc: bluca@debian.org, david.marchand@redhat.com, ian.stokes@intel.com, Ilya Maximets , Jerin Jacob , Ruifeng Wang , Honnappa Nagarahalli , konstantin.ananyev@intel.com, ferruh.yigit@intel.com References: <20201211155111.145279-1-bruce.richardson@intel.com> From: David Christensen Message-ID: Date: Wed, 15 Sep 2021 14:23:17 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 2Q1TMshvJSaNaNX_e3ZX8loiNBB8_sul X-Proofpoint-ORIG-GUID: GajZmw4ikUfr9omXQwsEpR5UjNNY1qL7 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.687,Hydra:6.0.235,FMLib:17.0.607.475 definitions=2020-10-13_15,2020-10-13_02,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 adultscore=0 lowpriorityscore=0 phishscore=0 clxscore=1011 priorityscore=1501 malwarescore=0 mlxlogscore=957 impostorscore=0 spamscore=0 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109030001 definitions=main-2109150102 Subject: Re: [dpdk-dev] [RFC PATCH] build/pkg-config: remove machine arch flag X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 9/15/21 9:28 AM, Bruce Richardson wrote: > On Fri, Dec 11, 2020 at 03:51:11PM +0000, Bruce Richardson wrote: >> Traditionally any apps built using DPDK had to support the same >> instruction sets as supported when the DPDK SDK itself was built, since >> that was "leaked" through to the end-app and DPDK headers via >> RTE_MACHINE_CPUFLAG_* values. Therefore, when converting over to meson >> for app build correctness the "-march=" flag was included in the >> pkg-config cflags output. >> >> However, since the DPDK-specific CPU flags are now obsolete, and we >> instead check directly for compiler-defined flags, we should no longer >> need to force the exact same architecture match in all cases. To >> faciliate such flexibility, a new pkg_config_machine_args array - which >> defaults to the existing machine_args array has been defined. The >> individual architectures - x86, arm and ppc - can choose if and how to >> override this value themselves. >> >> For x86, since SSE4.2 is the minimum instruction-set level needed to run >> DPDK, and since some header files assume that minimum level of >> instruction set support, we override the "-march=" value with "-msse4" >> for the pkg-config file. This allows end applications to set their own >> "march" value while still ensuring valid DPDK compilation. >> >> Signed-off-by: Bruce Richardson >> --- >> >> CC: Jerin Jacob >> CC: Ruifeng Wang >> CC: Honnappa Nagarahalli >> CC: David Christensen for >> Feedback requested from ARM and PPC maintainers as to this change >> and what flags, if any, need to be in the .pc file for DPDK on such >> platforms. For example - is setting 'pkg_config_machine_args' to >> 'machine_args' by default necessary behaviour? >> > > Ping for further thoughts or input on this patch. On initial inspection I don't see any additional value for PPC systems. Selection of a CPU through -mcpu implies a full ISA for that CPU, including things like vector extensions, at least with respect to the minimum supported POWER8 CPU (ISA 2.07) and later ISAs. The values of machine_args and pkg_config_machine_args should be identical in all cases I can think of. If a third party OpenPOWER CPU comes along some time in the future then the requirements may change. Dave