From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755208Ab2ITN1y (ORCPT ); Thu, 20 Sep 2012 09:27:54 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:56260 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753495Ab2ITN1w (ORCPT ); Thu, 20 Sep 2012 09:27:52 -0400 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm: introduce a DTS for Xen unprivileged virtual machines Date: Thu, 20 Sep 2012 13:27:45 +0000 User-Agent: KMail/1.12.2 (Linux/3.5.0; KDE/4.3.2; x86_64; ; ) Cc: Ian Campbell , Stefano Stabellini , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" , Pawel Moll , "konrad.wilk@oracle.com" References: <1348076658-4511-1-git-send-email-stefano.stabellini@eu.citrix.com> <1348143533.26501.28.camel@zakaz.uk.xensource.com> In-Reply-To: <1348143533.26501.28.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201209201327.45802.arnd@arndb.de> X-Provags-ID: V02:K0:MbamWzyfXUWMJ4bda6+S6Fl6++JJwT+lvfOV1RSoIMq fblgtv0+qKgmgbvcArD1nwhvEElfTCXnkzOxIZunO8hxtz/X61 hUe5TmeAQEdrkxP1HkJnHRFkO94UhGLlZCS9bKCL7aA4bCGF6q xBNxffC20ZQBTIJemklzXDtCReJCUD46RCHqmvk6qaiQOnv7Se MwcpF491XefSCKBlEGE7px9eJbnMINpFeLsKkGah/OPs/9n+9I 3NYD7yvkzz4uUH+6eokrYcGUMMVrev8+BNUiDTD483lf3g5+IB oY+93PV4dM5Xgx6TAhD4kzkpnoOL3sr3Q800ynTBB0HdC1IsOQ ZbBxse1F0TI+qiM+Ribk= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 20 September 2012, Ian Campbell wrote: > On Thu, 2012-09-20 at 12:56 +0100, Stefano Stabellini wrote: > > On Thu, 20 Sep 2012, Ian Campbell wrote: > > > On Wed, 2012-09-19 at 18:44 +0100, Stefano Stabellini wrote: > > > > + compatible = "xen,xenvm-4.2", "arm,vexpress"; > > > > > > Is this second compatible thing actually true? We don't actually emulate > > > much (anything?) of what would be on a real vexpress motherboard. > > > > > > "arm,vexpress" is used only in v2m.c and I don't think we want the > > > majority of that -- we don't provide any of the peripherals which it > > > registers. > > > > > > I think the only things we might want out of that lot are the arch timer > > > and perhaps the uart0 (as a debug port). > > > > > > I suspect we should have our own xen machine .c. > > > > > > [...] > > > > It is true that we are "arm,vexpress" compatible at the moment. > > But we aren't, we don't emulate 90%+ of the actual hardware which > vexpress compatibility would actually imply. > > Look in arch/arm/mach-vexpress/v2m.c, which is the only thing keyed off > this compat value -- it's full of stuff which we don't (and aren't going > to) implement. It's not much different in the end, but I think I'd rather make the compatible list in the device tree "xen,xenvm-4.2", "xen,xenvm" without listing "arm,vexpress", but then adding "xen,xenvm" to the list of compatible devices in the vexpress kernel code. The main difference is that if we decide to separate out the Linux code for Xen and vexpress later into distinct ports, we have the option to do that. vexpress will support multiplatform configurations in 3.7 anyway, so the idea of making all virtual platforms part of vexpress in order to be able to boot the same kernel on them is not all that important any more. Arnd