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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 B321BC433E5 for ; Mon, 3 Aug 2020 06:57:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89C59206E9 for ; Mon, 3 Aug 2020 06:57:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Imiqwh2w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727060AbgHCG5C (ORCPT ); Mon, 3 Aug 2020 02:57:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726224AbgHCG5C (ORCPT ); Mon, 3 Aug 2020 02:57:02 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFBB4C06174A; Sun, 2 Aug 2020 23:57:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=S81Y7/E/1KRByHOMFTAO1WQMOll7HWoP+pv/fCo/3sI=; b=Imiqwh2wh6gfO95HVgGWdIpJ7R qFqJDaURIpsOiDpUCq2k3ILdHp9/G64PbhflfbfwXUHR3YCqdMM2JIr5p2HV5QlEFNjYcibq1cAwB k5jcDFqNUiYh1ErghhsIpsN5baKyFw50AsjkOnyh0RkcQvG4I/FuQV4i+K4smxUlt0gQ8ZINX4zk1 zqYZrKBpxdTsr3nucjd2JPKqfEkufPqh/aFaSwGu2mFtFylC2a36pyZdPfsQXEbP1+7In5Kkj2kTD iIuAdnnH0jCfMh5vNRvgFzTjztCURqfBsmyFjwViAe1IQB++yIvaVvpqhNNNwV/B+lmZFzbHjUNTv QTu3Qcmg==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k2UOb-0005Zd-6v; Mon, 03 Aug 2020 06:56:29 +0000 Date: Mon, 3 Aug 2020 07:56:29 +0100 From: Christoph Hellwig To: Bjorn Helgaas Cc: Borislav Petkov , Saheed Bolarinwa , trix@redhat.com, Kalle Valo , "David S. Miller" , Jakub Kicinski , Wolfgang Grandegger , Marc Kleine-Budde , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Joerg Roedel , bjorn@helgaas.com, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-mtd@lists.infradead.org, iommu@lists.linux-foundation.org, linux-rdma@vger.kernel.org, linux-ide@vger.kernel.org, linux-i2c@vger.kernel.org, linux-hwmon@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-gpio@vger.kernel.org, linux-fpga@vger.kernel.org, linux-edac@vger.kernel.org, dmaengine@vger.kernel.org, linux-crypto@vger.kernel.org, linux-atm-general@lists.sourceforge.net Subject: Re: [RFC PATCH 00/17] Drop uses of pci_read_config_*() return value Message-ID: <20200803065629.GA19534@infradead.org> References: <20200802184648.GA23190@nazgul.tnic> <20200802191406.GA248232@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200802191406.GA248232@bjorn-Precision-5520> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On Sun, Aug 02, 2020 at 02:14:06PM -0500, Bjorn Helgaas wrote: > But what guarantees that a PCI config register cannot contain ~0? > If there's something about that in the spec I'd love to know where it > is because it would simplify a lot of things. There isn't. An we even have cases like the NVMe controller memory buffer and persistent memory region, which are BARs that store abritrary values for later retreival, so it can't. (now those features have a major issue with error detection, but that is another issue)