From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] pci-assign: Hide ioport regions on lacking sysfs support Date: Wed, 30 May 2012 10:47:34 +0200 Message-ID: <4FC5DEA6.5040607@siemens.com> References: <4FC501BA.5010105@siemens.com> <4FC503CD.6010804@redhat.com> <1338312532.4714.139.camel@ul30vt> <4FC5D872.6080702@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Alex Williamson , Marcelo Tosatti , kvm To: Avi Kivity Return-path: Received: from goliath.siemens.de ([192.35.17.28]:26232 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932333Ab2E3Irk (ORCPT ); Wed, 30 May 2012 04:47:40 -0400 In-Reply-To: <4FC5D872.6080702@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2012-05-30 10:21, Avi Kivity wrote: > On 05/29/2012 08:28 PM, Alex Williamson wrote: >> On Tue, 2012-05-29 at 20:13 +0300, Avi Kivity wrote: >>> On 05/29/2012 08:04 PM, Jan Kiszka wrote: >>>> As suggested by Alex: Instead of failing if the kernel does not allow us >>>> to speak to an ioport region, warn the user but, hide the region and >>>> continue. >>> >>> >>> Should we not, in addition, abort if the region is actually used? A >>> guest malfunction is likely if we don't. >> >> The only way we could know that it's used is if it's the device ends up >> with no valid regions as a result of this. Otherwise it's dependent on >> both the device and the driver whether it can still function without the >> i/o port regions. Thanks, > > If the I/O callback is called, we know it's used. We neither expose the region to the guest (so the guest has no clue where to write to unless it assumes a fixed address - of which we have no clue) nor register any callback for it. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux