Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756696Ab2K0SKp (ORCPT ); Tue, 27 Nov 2012 13:10:45 -0500 Received: from webmail.solarflare.com ([12.187.104.25]:10857 "EHLO webmail.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756264Ab2K0SKo (ORCPT ); Tue, 27 Nov 2012 13:10:44 -0500 Message-ID: <1354039840.2701.14.camel@bwh-desktop.uk.solarflarecom.com> Subject: RE: [E1000-devel] 82571EB: Detected Hardware Unit Hang From: Ben Hutchings To: "Fujinaka, Todd" , Mary Mcgrath CC: Joe Jin , "netdev@vger.kernel.org" , "e1000-devel@lists.sf.net" , "linux-kernel@vger.kernel.org" , linux-pci Date: Tue, 27 Nov 2012 18:10:40 +0000 In-Reply-To: <9B4A1B1917080E46B64F07F2989DADD62F2D8070@ORSMSX102.amr.corp.intel.com> References: <509B5038.8090304@oracle.com> <061C8A8601E8EE4CA8D8FD6990CEA89133487884@ORSMSX102.amr.corp.intel.com> <50A30656.6090508@oracle.com> <061C8A8601E8EE4CA8D8FD6990CEA8913348B105@ORSMSX102.amr.corp.intel.com> <50A43828.6000702@oracle.com> <061C8A8601E8EE4CA8D8FD6990CEA8913349A0B4@ORSMSX102.amr.corp.intel.com> <50A9C5CC.1030300@oracle.com> <061C8A8601E8EE4CA8D8FD6990CEA8913349EB41@ORSMSX102.amr.corp.intel.com> <50AB8471.7080607@oracle.com> <9B4A1B1917080E46B64F07F2989DADD62F2D62D6@ORSMSX102.amr.corp.intel.com> <50B41077.3080009@oracle.com> <9B4A1B1917080E46B64F07F2989DADD62F2D8070@ORSMSX102.amr.corp.intel.com> Organization: Solarflare Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 (3.2.3-3.fc16) Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-Originating-IP: [10.17.20.137] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1475 Lines: 34 On Tue, 2012-11-27 at 17:32 +0000, Fujinaka, Todd wrote: > Forgive me if I'm being too repetitious as I think some of this has > been mentioned in the past. > > We (and by we I mean the Ethernet part and driver) can only change the > advertised availability of a larger MaxPayloadSize. The size is > negotiated by both sides of the link when the link is established. The > driver should not change the size of the link as it would be poking at > registers outside of its scope and is controlled by the upstream > bridge (not us). [...] MaxPayloadSize (MPS) is not negotiated between devices but is programmed by the system firmware (at least for devices present at boot - the kernel may be responsible in case of hotplug). You can use the kernel parameter 'pci=pcie_bus_perf' (or one of several others) to set a policy that overrides this, but no policy will allow setting MPS above the device's MaxPayloadSizeSupported (MPSS). (These parameters are not documented in Documentation/kernel-parameters.txt! Someone ought to fix that.) Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/