From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755073Ab2ITMS6 (ORCPT ); Thu, 20 Sep 2012 08:18:58 -0400 Received: from smtp.ctxuk.citrix.com ([62.200.22.115]:7147 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755016Ab2ITMSz (ORCPT ); Thu, 20 Sep 2012 08:18:55 -0400 X-IronPort-AV: E=Sophos;i="4.80,453,1344211200"; d="scan'208";a="14655251" Message-ID: <1348143533.26501.28.camel@zakaz.uk.xensource.com> Subject: Re: [PATCH] arm: introduce a DTS for Xen unprivileged virtual machines From: Ian Campbell To: Stefano Stabellini CC: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" , "konrad.wilk@oracle.com" , Pawel Moll , "linux-arm-kernel@lists.infradead.org" Date: Thu, 20 Sep 2012 13:18:53 +0100 In-Reply-To: References: <1348076658-4511-1-git-send-email-stefano.stabellini@eu.citrix.com> <1348136222.26501.19.camel@zakaz.uk.xensource.com> Organization: Citrix Systems, Inc. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.3-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: > > > +/include/ "skeleton.dtsi" > > > + > > > +/ { > > > + model = "XENVM-4.2"; > > > > Why the shouty caps? > > It looks like that model names are always capital, at least in the > vexpress family. > > > > Did you mean 4.3 here and throughout? > > Nope, after all this is the fruit of the work we did on Xen 4.2, mostly > already upstream. By the time of the 4.3 release we might have a > different dts. > > > > > + 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. > Also we need to be unless we want to introduce our own arch/arm/mach-xen > that I think is overkill. Probably. > Versatile Express is flexible enough to be a good base for our own > virtual machine platform, especially if the maintainers keep an eye on > getting everything through DT and not expecting devices just to be there > ;-) Perhaps what we want is a stricter subset of the stuff in mach-vexpress then. But if so then this should be expressed both in the DT and in the code, not just papered over by declaring things compatible when they are not. > > > + gic: interrupt-controller@2c001000 { > > > + compatible = "arm,cortex-a9-gic"; > > > > Don't we mean "arm,cortex-a15-gic" here? That's what we actually > > provide. I'm not sure how the a9 and a15 differ. > > The GIC that comes with vexpress is a9 compatible. The GIC which Xen emulates is the one which matters here though, and that is an a15. Ian.