From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752169AbZF0LaO (ORCPT ); Sat, 27 Jun 2009 07:30:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751415AbZF0LaC (ORCPT ); Sat, 27 Jun 2009 07:30:02 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:41028 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751312AbZF0LaA (ORCPT ); Sat, 27 Jun 2009 07:30:00 -0400 Date: Wed, 24 Jun 2009 17:05:36 +0200 From: Pavel Machek To: Joseph Cihula Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, arjan@linux.intel.com, hpa@zytor.com, andi@firstfloor.org, chrisw@sous-sol.org, jmorris@namei.org, jbeulich@novell.com, peterm@redhat.com, gang.wei@intel.com, shane.wang@intel.com Subject: Re: [RFC v5][PATCH 4/4] intel_txt: force IOMMU on for Intel(R) TXT launch Message-ID: <20090624150536.GL1784@ucw.cz> References: <4A4024C5.3020702@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A4024C5.3020702@intel.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2009-06-22 17:41:41, Joseph Cihula wrote: > The tboot module will DMA protect all of memory in order to ensure the that > kernel will be able to initialize without compromise (from DMA). Consequently, > the kernel must enable Intel(R) Virtualization Technology for Directed I/O > (VT-d or Intel IOMMU) in order to replace this broad protection with the > appropriate page-granular protection. Otherwise DMA devices will be unable > to read or write from memory and the kernel will eventually panic. > > Because runtime IOMMU support is configurable by command line options, this > patch will force it to be enabled regardless of the options specified, and will > log a message if it was required to force it on. > > > dmar.c | 8 ++++++++ > intel-iommu.c | 28 ++++++++++++++++++++++++++-- > 2 files changed, 34 insertions(+), 2 deletions(-) This needs documentation. And you probably should panic the kernel if user passes unworkable options, not override his choices. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html