From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751823AbdJ3BEv (ORCPT ); Sun, 29 Oct 2017 21:04:51 -0400 Received: from mail-dm3nam03on0102.outbound.protection.outlook.com ([104.47.41.102]:43088 "EHLO NAM03-DM3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751429AbdJ3BEt (ORCPT ); Sun, 29 Oct 2017 21:04:49 -0400 From: "Stephen Bates" To: Christoph Hellwig CC: "corbet@lwn.net" , "bhelgaas@google.com" , "paulmck@linux.vnet.ibm.com" , "tglx@linutronix.de" , "akpm@linux-foundation.org" , "mingo@kernel.org" , "cdall@linaro.org" , "marc.zyngier@arm.com" , "zohar@linux.vnet.ibm.com" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "logang@deltatee.com" , "tom@talpey.com" Subject: Re: [PATCH] pci: Add a acs_disable option for pci kernel parameter Thread-Topic: [PATCH] pci: Add a acs_disable option for pci kernel parameter Thread-Index: AQHTTsyaGSPW2+ZeiEyBBlZtDyHwgqL3PpiAgARZ9gA= Date: Mon, 30 Oct 2017 01:04:47 +0000 Message-ID: <7AEEED4D-1C64-4330-96E2-AB665E3D4B7D@raithlin.com> References: <1509071869-18771-1-git-send-email-sbates@raithlin.com> <20171027063745.GA19799@infradead.org> In-Reply-To: <20171027063745.GA19799@infradead.org> Accept-Language: en-CA, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/f.27.0.171010 authentication-results: spf=none (sender IP is ) smtp.mailfrom=sbates@raithlin.com; 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This is useful for PCI peer to >> peer communication but can cause problems when IOVA isolation is >> required and an IOMMU is enabled. Use with care. > Eww. Thanks for the feedback Christoph. My sentiments exactly ;-). > Can we please add smbios quirks for the systems where you've > observed this? I can look at doing this. The issue with this approach is that it will require a kernel patch for each new system that is detected. > we probably also want to keep the option just in case). Agreed. At least then operators have a path to ACS disable prior to a quirk being accepted. Stephen