From owner-freebsd-current@FreeBSD.ORG Thu Dec 20 01:37:24 2007 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D40AA16A419 for ; Thu, 20 Dec 2007 01:37:24 +0000 (UTC) (envelope-from ache@nagual.pp.ru) Received: from nagual.pp.ru (nagual.pp.ru [194.87.13.69]) by mx1.freebsd.org (Postfix) with ESMTP id 452D513C442 for ; Thu, 20 Dec 2007 01:37:23 +0000 (UTC) (envelope-from ache@nagual.pp.ru) Received: from nagual.pp.ru (ache@localhost [127.0.0.1]) by nagual.pp.ru (8.14.2/8.14.2) with ESMTP id lBK1bM2i091864; Thu, 20 Dec 2007 04:37:22 +0300 (MSK) (envelope-from ache@nagual.pp.ru) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=nagual.pp.ru; s=default; t=1198114642; bh=0SSsCxtO4XqiUgCF0pmlSNeFjozL44Rih82+22l afG4=; l=1662; h=Date:From:To:Cc:Subject:Message-ID: Mail-Followup-To:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To:User-Agent; b=lhREw2rfjDwCTKokuvKl Gx7r5mTb73F0B0b08gQNexTXD/vtpL7RsgTxevJWQSGNSMe/iqdpwnhiZcgdKAGwzGX 7c0fbKXRM6F4WAgSQJf4QOh+5TUc6gs7+HB2ZRhpHKphi3vRfyul538JKft+KwtXl9k cjmTIxCAp1lrRIwUw= Received: (from ache@localhost) by nagual.pp.ru (8.14.2/8.14.2/Submit) id lBK1bMfO091863; Thu, 20 Dec 2007 04:37:22 +0300 (MSK) (envelope-from ache) Date: Thu, 20 Dec 2007 04:37:20 +0300 From: Andrey Chernov To: Pyun YongHyeon Message-ID: <20071220013720.GA91833@nagual.pp.ru> Mail-Followup-To: Andrey Chernov , Pyun YongHyeon , current@freebsd.org References: <20071219013343.GA38367@nagual.pp.ru> <20071220012521.GA993@cdnetworks.co.kr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071220012521.GA993@cdnetworks.co.kr> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: current@freebsd.org Subject: Re: Question about dev.fxp.0.noflow X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Dec 2007 01:37:24 -0000 On Thu, Dec 20, 2007 at 10:25:22AM +0900, Pyun YongHyeon wrote: > On Wed, Dec 19, 2007 at 04:33:44AM +0300, Andrey Chernov wrote: > > Does anybody know why dev.fxp.0.noflow=1 by default? > > Is it more proper to set it to 0? (by default or via /etc/sysctl.conf) > > > > Since flow control is valid only when link partner also agrees on > advertised pause capability on full-duplex media, it needs more work > in mii/phy driver to advertise correct pause capability. It also needs > a way to pass negotiated pause capability back to drvier such that > each drvier should program necessary flow control parameters depending > on its MAC capability and negociated ones. Just enabling flow control > on one side have no effect. I also found this note in the commit log: date: 2003/05/16 01:13:16; author: rwatson; state: Exp; lines: +5 -1 Add a tunable/sysctl "hw.fxp_noflow" which disables flow control support on if_fxp cards. When flow control is enabled, if the operating system doesn't acknowledge the packet buffer filling, the card will begin to generate ethernet quench packets, but appears to get into a feedback loop of some sort, hosing local switches. This is a temporary workaround for 5.1: the ability to configure flow control should probably be exposed by some or another management interface on ethernet link layer devices. Does it mean card hardware defect or lack of driver support? I.e. is this phrase "When flow control is enabled, if the operating system doesn't acknowledge the packet buffer filling" still true with latest drivers framework (the note as old as 2003)? -- http://ache.pp.ru/