From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [net-2.6 PATCH] ixgbe: add IntMode module parameter Date: Sun, 18 Apr 2010 22:09:31 -0700 (PDT) Message-ID: <20100418.220931.39174434.davem@davemloft.net> References: <20100419050315.24758.62479.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, gospo@redhat.com, nicholasx.d.nunley@intel.com, john.ronciak@intel.com To: jeffrey.t.kirsher@intel.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:47476 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751095Ab0DSFJ0 (ORCPT ); Mon, 19 Apr 2010 01:09:26 -0400 In-Reply-To: <20100419050315.24758.62479.stgit@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: From: Jeff Kirsher Date: Sun, 18 Apr 2010 22:03:59 -0700 > This patch adds the IntMode module parameter to ixgbe to allow > user selection of interrupt mode (MSI-X, MSI, legacy) on driver > load. To work around the errata described above, ixgbe needs to > be able to disable MSI-X for affected configurations. This is not how we handle situations like this. Here is one acceptable way to handle this: Turn MSI/MSI-X off for every system that uses this PCI-E complex chipset. Add a whitelist that allows enabling. Here is another: Turn MSI/MSI-X on by default and have blacklists. Anything that requires unusual user interactions, such as specifying special module parameters, for correct operations is absolutely unacceptable. I don't want to hear how difficult it is to determine whether a system will hit this bug or not. If it's hard, just turn MSI off unconditionally with this chipset until you can detect things properly.