From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755115Ab2ITM24 (ORCPT ); Thu, 20 Sep 2012 08:28:56 -0400 Received: from service87.mimecast.com ([91.220.42.44]:53890 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754664Ab2ITM2y convert rfc822-to-8bit (ORCPT ); Thu, 20 Sep 2012 08:28:54 -0400 Message-ID: <505B0C00.5010003@arm.com> Date: Thu, 20 Sep 2012 13:28:48 +0100 From: Marc Zyngier User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120714 Thunderbird/14.0 MIME-Version: 1.0 To: Stefano Stabellini CC: Pawel Moll , "linux-kernel@vger.kernel.org" , Ian Campbell , "xen-devel@lists.xensource.com" , "konrad.wilk@oracle.com" , "linux-arm-kernel@lists.infradead.org" , Arnd Bergmann Subject: Re: [PATCH] arm: introduce a DTS for Xen unprivileged virtual machines References: <1348076658-4511-1-git-send-email-stefano.stabellini@eu.citrix.com> <1348135563.11116.94.camel@hornet> <1348142133.11116.109.camel@hornet> In-Reply-To: X-Enigmail-Version: 1.5a1pre X-OriginalArrivalTime: 20 Sep 2012 12:28:49.0423 (UTC) FILETIME=[7CA5A1F0:01CD972B] X-MC-Unique: 112092013285202501 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/09/12 13:15, Stefano Stabellini wrote: > On Thu, 20 Sep 2012, Pawel Moll wrote: >> On Thu, 2012-09-20 at 12:39 +0100, Stefano Stabellini wrote: >>> There are no peripherals apart from the ones that are already described >>> here (timer, gic). All the peripherals that the guest sees are virtual >>> devices that show up on xenbus (a virtual bus). In order to initialize >>> xenbus, the guest only needs the hypervisor node. So I'll remove the >>> ranges and interrupt-map. >> >> So all the peripherals are actually discoverable - awesome! >> >> But the fact is that the only "vexpressness" of this tree is >> memory@80000000 and gic@2c001000. The rest (not much of it ;-) is a >> "generic A15 platform". >> >> I understand that you had to use some "compatible" value to get >> initialization code and I'm flattered ;-) by your choice of >> "arm,vexpress", but maybe - as suggested by others - you would be better >> off with generating this stuff in runtime, by whatever tool is used to >> instantiate the guest? > > Yes, it is certainly going to be generated at run time. Does it make > sense to keep an example under arch/arm/boot/dts? I think so. There must > be other platforms that actually pass the device tree to the kernel from > the firmware and still have a dts in the kernel tree, right? > If actually there are none, it is probably best to forget about this > patch :) > > Regarding the choice of "arm,vexpress", there was a discussion at kernel > summit about vexpress being the right choice as a base platform for > virtual machines on ARM, even though in the Xen case it means having a > vexpress with no peripherals. I think the important thing here is that the memory map is RS1. As this is a (very limited) subset of a vexpress A15, it seems to make some sense. I still think it is useful at have an example of such a platform in the tree, if only as a very minimal example. M. -- Jazz is not dead. It just smells funny...