From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755364Ab2ITOMr (ORCPT ); Thu, 20 Sep 2012 10:12:47 -0400 Received: from smtp.eu.citrix.com ([62.200.22.115]:13613 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753903Ab2ITOMq (ORCPT ); Thu, 20 Sep 2012 10:12:46 -0400 X-IronPort-AV: E=Sophos;i="4.80,453,1344211200"; d="scan'208";a="14659955" Date: Thu, 20 Sep 2012 15:11:56 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Arnd Bergmann CC: "linux-arm-kernel@lists.infradead.org" , Ian Campbell , Stefano Stabellini , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" , Pawel Moll , "konrad.wilk@oracle.com" Subject: Re: [PATCH] arm: introduce a DTS for Xen unprivileged virtual machines In-Reply-To: <201209201327.45802.arnd@arndb.de> Message-ID: References: <1348076658-4511-1-git-send-email-stefano.stabellini@eu.citrix.com> <1348143533.26501.28.camel@zakaz.uk.xensource.com> <201209201327.45802.arnd@arndb.de> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 20 Sep 2012, Arnd Bergmann wrote: > 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. That's a very good idea, I'll do that.