From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by dpdk.org (Postfix) with ESMTP id 2076C1B7CF for ; Wed, 25 Oct 2017 10:36:39 +0200 (CEST) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga105.fm.intel.com with ESMTP; 25 Oct 2017 01:36:38 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,431,1503385200"; d="scan'208";a="1235003132" Received: from bricha3-mobl3.ger.corp.intel.com ([10.237.221.32]) by fmsmga002.fm.intel.com with SMTP; 25 Oct 2017 01:36:37 -0700 Received: by (sSMTP sendmail emulation); Wed, 25 Oct 2017 09:36:36 +0100 Date: Wed, 25 Oct 2017 09:36:35 +0100 From: Bruce Richardson To: Wenzhuo Lu Cc: dev@dpdk.org Message-ID: <20171025083635.GA13488@bricha3-MOBL3.ger.corp.intel.com> References: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com> Organization: Intel Research and Development Ireland Ltd. User-Agent: Mutt/1.9.1 (2017-09-22) 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: Wed, 25 Oct 2017 08:36:40 -0000 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 > --- Good idea to document this better. > 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 ethertype \ > 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 descriptor. I assume that 2.1.26 is referring to the i40e driver version, not the linux kernel version. This should be made clearer, as it also could be read as a very old kernel version. > 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=n`` in > config file. Can you explain - either on-list here, or actually in the docs - why there is this restriction? Is it HW or SW? A reference to the section in the datasheet 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. > +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 > Regards, /Bruce