From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755108Ab2FFI3P (ORCPT ); Wed, 6 Jun 2012 04:29:15 -0400 Received: from mail-bk0-f46.google.com ([209.85.214.46]:57710 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754844Ab2FFI3G (ORCPT ); Wed, 6 Jun 2012 04:29:06 -0400 Date: Wed, 6 Jun 2012 10:29:00 +0200 From: Ingo Molnar To: David Woodhouse Cc: Don Dutile , iommu@lists.linux-foundation.org, mingo@elte.hu, linux-kernel@vger.kernel.org, chrisw@redhat.com, suresh.b.siddha@intel.com Subject: Re: [PATCH 2/2] iommu: dmar -- reserve mmio space used by IOMMU Message-ID: <20120606082900.GF5991@gmail.com> References: <1338845342-12464-1-git-send-email-ddutile@redhat.com> <1338845342-12464-3-git-send-email-ddutile@redhat.com> <1338849430.10884.288.camel@shinybook.infradead.org> <4FCD401D.9000304@redhat.com> <1338852196.26785.10.camel@shinybook.infradead.org> <20120606081600.GB5991@gmail.com> <1338971183.26785.33.camel@shinybook.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338971183.26785.33.camel@shinybook.infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * David Woodhouse wrote: > On Wed, 2012-06-06 at 10:16 +0200, Ingo Molnar wrote: > > > So basically the patch-set is fine as-is, we just want a > > sufficiently nasty sounding warning message about the BIOS > > bug, > > No. The other change that's required is that the warning and > the workaround need to trigger even when IOMMU support isn't > built into the kernel. This BIOS bug can bite you even when > you aren't *using* the IOMMU. Right, but that's the status quo and most of the time (distro kernels) the driver is available, right? So for all practical purposes we get 99% of the warning power without going into chicken-and-egg problems like how do we determine that there's an IOMMU area there if there's no IOMMU aware code in the kernel, right? Thanks, Ingo