From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by dpdk.org (Postfix) with ESMTP id 3716214EC; Wed, 10 May 2017 10:37:03 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP; 10 May 2017 01:37:02 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.38,318,1491289200"; d="scan'208";a="1146072535" Received: from bricha3-mobl3.ger.corp.intel.com ([10.237.221.42]) by fmsmga001.fm.intel.com with SMTP; 10 May 2017 01:37:00 -0700 Received: by (sSMTP sendmail emulation); Wed, 10 May 2017 09:37:00 +0100 Date: Wed, 10 May 2017 09:36:59 +0100 From: Bruce Richardson To: "Coulson, Ken" Cc: "dev@dpdk.org" , "users@dpdk.org" Message-ID: <20170510083659.GA5268@bricha3-MOBL3.ger.corp.intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Research and =?iso-8859-1?Q?De=ACvel?= =?iso-8859-1?Q?opment?= Ireland Ltd. User-Agent: Mutt/1.8.0 (2017-02-23) Subject: Re: [dpdk-users] [dpdk-dev] Question about driver/controller MTU enforcement with MTU less than jumbo frame size X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 May 2017 08:37:04 -0000 On Tue, May 09, 2017 at 09:02:24PM +0000, Coulson, Ken wrote: > Is it possible to have an MTU enforced on rx that is less than jumbo size frames? > From the DPDK driver code snippet for ixgbe if MTU < 1518 then the jumbo_frame control bit in the chip is set to 0. > The controller manual says the maximum frame size is only meaningful when the jumbo_frame control bit is 1. > Does it work to leave jumbo_frame set to 1 but set max frame size to something smaller than the jumbo size of 1518? > I believe it should work, but I haven't ever tested it to confirm. /Bruce