From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751457Ab2DBH66 (ORCPT ); Mon, 2 Apr 2012 03:58:58 -0400 Received: from mout6.freenet.de ([195.4.92.96]:55069 "EHLO mout6.freenet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082Ab2DBH65 (ORCPT ); Mon, 2 Apr 2012 03:58:57 -0400 Message-ID: <4F795BA8.7020404@01019freenet.de> Date: Mon, 02 Apr 2012 09:56:24 +0200 From: Andreas Hartmann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120312 Firefox/11.0 SeaMonkey/2.8 MIME-Version: 1.0 To: KVM , Kernel-Mailingliste Subject: AMD iommu: Difference between setting iommu=pt and not setting this option X-Enigmail-Version: 1.4 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, please, could somebody explain the difference in behaviour between setting the boot option iommu=pt and not setting it? I can see the following differences: w/ iommu=pt: [ 0.832946] AMD-Vi: Enabling IOMMU at 0000:00:00.2 cap 0x40 [ 0.883983] AMD-Vi: Initialized for Passthrough Mode w/o iommu=pt: [ 0.834905] AMD-Vi: Enabling IOMMU at 0000:00:00.2 cap 0x40 [ 0.894172] AMD-Vi: Lazy IO/TLB flushing enabled In both cases, I can pass through a PCIe device but not a PCI device (-> no problem with IRQ-sharing - the PCI device has its own exclusive IRQ). If I use iommu=pt, the passed PCIe device is broken after the VM has been shutdown and started again. Thank you, kind regards, Andreas