From mboxrd@z Thu Jan 1 00:00:00 1970 From: Loic Prylli Subject: Re: [PATCH] pciaer: report config read/write errors Date: Tue, 02 Dec 2008 15:14:35 -0500 Message-ID: <4935972B.8050608@myri.com> References: <20081202004115.12058.64881.stgit@gitlost.lost> <20081201174754.2e5ef401@extreme> <20081201.232527.66213356.davem@davemloft.net> <20081202092316.7d6b6291@extreme> <493586AF.3030402@myri.com> <20081202114441.4389fab7@extreme> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Miller , jeffrey.t.kirsher@intel.com, netdev@vger.kernel.org, jeff@garzik.org, peter.p.waskiewicz.jr@intel.com, linux-pci@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mailbox2.myri.com ([64.172.73.26]:1978 "EHLO myri.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750718AbYLBUOp (ORCPT ); Tue, 2 Dec 2008 15:14:45 -0500 In-Reply-To: <20081202114441.4389fab7@extreme> Sender: netdev-owner@vger.kernel.org List-ID: On 12/02/2008 02:44 PM, Stephen Hemminger wrote: > pci_find_ext_capability would succeed but all access to registers >= 256 > would fail if MMCONFIG failed. Your sentence seems self-contradicting to me. pci_find_ext_capability() (!= pci_find_capability()) only tries to access registers >= 256, so I don't see how it would succeed if *all* those accesses are failing. > P.s: you can look back into LKML for Linus discussion about why MMCONFIG > is broken anyway. > I was an active participant in one of those discussions (although it is possible I missed a later one), so I am quite aware about the limitations of MMCONFIG. But pci_find_ext_capability() looked to me a good filter to check about those limitations(). This is not just about pciaer, for instance, it might be that a lot of the SR-IOV code submitted recently assumes that if the corresponding extended-capability can be detected, little checking needs to be done afterwards. Loic