From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758569AbYGKBzR (ORCPT ); Thu, 10 Jul 2008 21:55:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752932AbYGKBzF (ORCPT ); Thu, 10 Jul 2008 21:55:05 -0400 Received: from mga02.intel.com ([134.134.136.20]:58313 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751962AbYGKBzD (ORCPT ); Thu, 10 Jul 2008 21:55:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.30,341,1212390000"; d="scan'208";a="409836183" Date: Thu, 10 Jul 2008 18:55:02 -0700 From: Suresh Siddha To: Andrew Morton Cc: Yong Wang , "linux-kernel@vger.kernel.org" , "Siddha, Suresh B" Subject: Re: [PATCH] Intel IOMMU: RMRRs do not necessarily have to be present on all VT-d capable platforms Message-ID: <20080711015502.GP1678@linux-os.sc.intel.com> References: <20080701091354.GA12969@ywang-dev> <20080710010149.a73d779c.akpm@linux-foundation.org> <20080710235326.GA21208@ywang-dev> <20080710173243.3de505c7.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080710173243.3de505c7.akpm@linux-foundation.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 10, 2008 at 05:32:43PM -0700, Andrew Morton wrote: > On Thu, 10 Jul 2008 19:53:26 -0400 Yong Wang wrote: > > > On Thu, Jul 10, 2008 at 01:01:49AM -0700, Andrew Morton wrote: > > > On Tue, 1 Jul 2008 05:13:54 -0400 Yong Wang wrote: > > > > > > > RMRRs do not necessarily have to be present on all VT-d capable platforms. > > > > The printk is just informational and does not need to be followed by an > > > > error return. > > > > > > > > Signed-off-by: Yong Y Wang > > > > --- > > > > dmar.c | 4 +--- > > > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > > > > > diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c > > > > index f941f60..8bf86ae 100644 > > > > --- a/drivers/pci/dmar.c > > > > +++ b/drivers/pci/dmar.c > > > > @@ -317,10 +317,8 @@ int __init dmar_table_init(void) > > > > return -ENODEV; > > > > } > > > > > > > > - if (list_empty(&dmar_rmrr_units)) { > > > > + if (list_empty(&dmar_rmrr_units)) > > > > printk(KERN_INFO PREFIX "No RMRR found\n"); > > > > - return -ENODEV; > > > > - } > > > > > > > > return 0; > > > > } > > > > > > >From your description I am unable to work out how important this fix is. > > > > > > Is it needed in 2.6.25.x? In 2.6.26? In 2.6.27? There's no way for me to > > > know :( > > > > Actually this is the same as Suresh' x2apic patch 05/26. The absence of RMRRs > > will prevent kernel from parsing IOxAPICs without this patch and thus leaves > > IOxAPICs in an uninitialized state. > > And what runtime effect does that have? Andrew, this is not urgent. It is now getting tracked as part of x2apic patchset. And also, this doesn't need to be backported to any kernel. thanks suresh