From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F306C4321D for ; Thu, 16 Aug 2018 21:18:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FB5121480 for ; Thu, 16 Aug 2018 21:18:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3FB5121480 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726048AbeHQATf (ORCPT ); Thu, 16 Aug 2018 20:19:35 -0400 Received: from mga05.intel.com ([192.55.52.43]:48053 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725856AbeHQATf (ORCPT ); Thu, 16 Aug 2018 20:19:35 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Aug 2018 14:18:52 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,248,1531810800"; d="scan'208";a="77468435" Received: from unknown (HELO localhost.localdomain) ([10.232.112.44]) by fmsmga002.fm.intel.com with ESMTP; 16 Aug 2018 14:18:52 -0700 Date: Thu, 16 Aug 2018 15:19:40 -0600 From: Keith Busch To: "Derrick, Jonathan" Cc: "helgaas@kernel.org" , "linux-kernel@vger.kernel.org" , "okaya@kernel.org" , "willy@infradead.org" , "liudongdong3@huawei.com" , "poza@codeaurora.org" , "linux-pci@vger.kernel.org" , "linux-doc@vger.kernel.org" Subject: Re: [PATCH 1/2] PCI/DPC: Add 'nodpc' parameter Message-ID: <20180816211940.GB7400@localhost.localdomain> References: <1534368400-2807-1-git-send-email-jonathan.derrick@intel.com> <20180816154940.GD5762@bombadil.infradead.org> <1534434641.17819.27.camel@intel.com> <20180816203111.GB10316@bhelgaas-glaptop.roam.corp.google.com> <1534452635.17819.53.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1534452635.17819.53.camel@intel.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 16, 2018 at 01:50:42PM -0700, Derrick, Jonathan wrote: > It can also be disabled with setpci, but is that any less of a hassle? > Genuine question to understand your point of view. That is not a real solution, IMO. 'setpci' is good to inject things for testing, but it changes config space without the kernel aware that you've done that, so it is inherently racey with other kernel threads touching pci config space. And the kernel or platform may end up undoing what you had 'setpci' do anyway with no immediate way to be notified it was changed.