From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by dpdk.org (Postfix) with ESMTP id 8D3341B248 for ; Tue, 31 Oct 2017 04:39:10 +0100 (CET) Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Oct 2017 20:39:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,322,1505804400"; d="scan'208";a="169823224" Received: from dpdk26.sh.intel.com ([10.67.110.152]) by fmsmga006.fm.intel.com with ESMTP; 30 Oct 2017 20:39:08 -0700 From: Wenzhuo Lu To: dev@dpdk.org Cc: Wenzhuo Lu Date: Tue, 31 Oct 2017 11:40:33 +0800 Message-Id: <1509421233-81295-1-git-send-email-wenzhuo.lu@intel.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com> References: <1508900093-9894-1-git-send-email-wenzhuo.lu@intel.com> Subject: [dpdk-dev] [PATCH v2] 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 03:39:11 -0000 The description of i40e 16 bytes descriptor is not clear enough. Add more details. Signed-off-by: Wenzhuo Lu --- doc/guides/nics/i40e.rst | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst index a0946e6..771620c 100644 --- a/doc/guides/nics/i40e.rst +++ b/doc/guides/nics/i40e.rst @@ -398,13 +398,24 @@ 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 +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Currently the VF's RX descriptor mode is decided by PF. There's no PF-VF +interface for VF to request the RX descriptor mode, also no interface to nofify +VF its own RX descriptor mode. +Until i40e 2.1.26, the Linux i40e driver doesn't support 16 bytes RX descriptor. 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. +is used as the VF driver, DPDK cannot choose 16 byte receive descriptor. The +reason is that the RX descriptor is already set to 32 bytes by the i40e kernel +driver. That is to say, user should keep +``CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n`` in config file. +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