From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH] arm: document "mach-virt" platform. Date: Thu, 30 Jan 2014 17:15:49 +0000 Message-ID: <1391102149.9495.39.camel@kazak.uk.xensource.com> References: <1391098262-15944-1-git-send-email-ian.campbell@citrix.com> <52EA83D6.9050506@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52EA83D6.9050506@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: Christopher Covington Cc: linux-kernel@vger.kernel.org, Mark Rutland , devicetree@vger.kernel.org, Pawel Moll , Stefano Stabellini , Marc Zyngier , Will Deacon , Rob Herring , Arnd Bergmann , Kumar Gala , Olof Johansson , linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On Thu, 2014-01-30 at 11:54 -0500, Christopher Covington wrote: > > +++ b/Documentation/devicetree/bindings/arm/mach-virt.txt > > @@ -0,0 +1,32 @@ > > +* Mach-virt "Dummy Virtual Machine" platform > > + > > +"mach-virt" is the smallest, dumbest platform possible, to be used as > > +a guest for Xen, KVM and other hypervisors. > > The platform is also useful to, and used by, simulators like QEMU in TCG mode. I can mention this, although I don't think the list needs to be exhaustive. It has no > > +properties/functionality of its own and is driven entirely by device > > +tree. > > I find this wording confusing. I read it as saying the platform has no > properties or functionality. Perhaps you could phrase it slightly differently, > such as having no properties or functionality beyond what's described in the > device tree. Yes, this is what I was trying to say, I'll update with something along those lines. > > +The platform may also provide hypervisor specific functionality > > +(e.g. PV I/O), if it does so then this functionality must be > > +discoverable (directly or indirectly) via device tree. > > I think it would be informative to provide pointers here to commonly used > paravirtualized devices, especially VirtIO PCI/MMIO. Under what criteria would something be eligible/appropriate to be listed? I was trying to avoid "advocating" any particular type of PV devices. We already have something of a problem with people incorrectly assuming that mach-virt == virtio, which is not the case. If we did want to include an explicit list here at a minimum I would also want to include the Xen PV devices as well and surely there would be others which ought to be included too. Ian.