From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id EAD771B264 for ; Tue, 31 Oct 2017 02:53:33 +0100 (CET) Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Oct 2017 18:53:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,321,1505804400"; d="scan'208";a="329864230" Received: from fmsmsx103.amr.corp.intel.com ([10.18.124.201]) by fmsmga004.fm.intel.com with ESMTP; 30 Oct 2017 18:53:32 -0700 Received: from fmsmsx102.amr.corp.intel.com (10.18.124.200) by FMSMSX103.amr.corp.intel.com (10.18.124.201) with Microsoft SMTP Server (TLS) id 14.3.319.2; Mon, 30 Oct 2017 18:53:32 -0700 Received: from shsmsx101.ccr.corp.intel.com (10.239.4.153) by FMSMSX102.amr.corp.intel.com (10.18.124.200) with Microsoft SMTP Server (TLS) id 14.3.319.2; Mon, 30 Oct 2017 18:53:31 -0700 Received: from shsmsx102.ccr.corp.intel.com ([169.254.2.175]) by SHSMSX101.ccr.corp.intel.com ([169.254.1.159]) with mapi id 14.03.0319.002; Tue, 31 Oct 2017 09:53:29 +0800 From: "Lu, Wenzhuo" To: "Richardson, Bruce" CC: "dev@dpdk.org" Thread-Topic: [dpdk-dev] [PATCH] doc: more clarification for i40e 16 bytes desc Thread-Index: AQHTTTx7TWyMEIfy/0iMEvwGYrYg+KLzuCaAgAmDChA= Date: Tue, 31 Oct 2017 01:53:29 +0000 Message-ID: <6A0DE07E22DDAD4C9103DF62FEBC09093B6DAF73@shsmsx102.ccr.corp.intel.com> References: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com> <20171025083635.GA13488@bricha3-MOBL3.ger.corp.intel.com> In-Reply-To: <20171025083635.GA13488@bricha3-MOBL3.ger.corp.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH] doc: more clarification for i40e 16 bytes desc X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Oct 2017 01:53:34 -0000 Hi Bruce, > -----Original Message----- > From: Richardson, Bruce > Sent: Wednesday, October 25, 2017 4:37 PM > To: Lu, Wenzhuo > Cc: dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH] doc: more clarification for i40e 16 bytes= desc >=20 > On Wed, Oct 25, 2017 at 10:54:53AM +0800, Wenzhuo Lu wrote: > > The description of i40e 16 bytes descriptor is not clear enough. Add > > more details. > > > > Signed-off-by: Wenzhuo Lu > > --- >=20 > Good idea to document this better. >=20 > > doc/guides/nics/i40e.rst | 11 +++++++++-- > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst index > > a0946e6..e0237a8 100644 > > --- a/doc/guides/nics/i40e.rst > > +++ b/doc/guides/nics/i40e.rst > > @@ -398,13 +398,20 @@ used to classify MPLS packet by using a command > in testpmd like: > > testpmd> ethertype_filter 0 add mac_ignr 00:00:00:00:00:00 ethertyp= e \ > > 0x8847 fwd queue > > > > -16 Byte Descriptor cannot be used on DPDK VF > > -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > +16 Bytes Descriptor setting on DPDK VF > > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > +Until 2.1.26, the Linux i40e driver doesn't support 16 bytes RX descri= ptor. >=20 > I assume that 2.1.26 is referring to the i40e driver version, not the lin= ux > kernel version. This should be made clearer, as it also could be read as = a very > old kernel version. OK, I'll change it to i40e 2.1.26. >=20 > > If the Linux i40e kernel driver is used as host driver, while DPDK > > i40e PMD is used as the VF driver, DPDK cannot choose 16 byte receive > > descriptor. That is to say, user should keep > > ``CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=3Dn`` in config file. >=20 > Can you explain - either on-list here, or actually in the docs - why ther= e is > this restriction? Is it HW or SW? A reference to the section in the datas= heet > for it would also be good. For example Table 8-10 in the datasheet lists = no > restriction on the Dsize bit in the queue context. It's not a HW limitation. To my opinion, it's SW design and implementation = limitation. I'll add more details. >=20 > > +In the future, if the Linux i40e driver supports 16 bytes RX > > +descriptor, user should make sure the DPDK VF uses the same RX > > +descriptor mode, 16 bytes or 32 bytes, as the PF driver. > > + > > +The same rule for DPDK PF + DPDK VF. The PF and VF should use the > > +same RX descriptor mode. Or the VF RX will not work. > > > > Receive packets with Ethertype 0x88A8 > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > -- > > 1.9.3 > > >=20 >=20 > Regards, > /Bruce