From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Alacrityvm-devel] [PATCH v3 3/6] vbus: add a "vbus-proxy" bus model for vbus_driver objects Date: Thu, 20 Aug 2009 13:08:59 +0300 Message-ID: <4A8D20BB.7020008@redhat.com> References: <20090818172752.GC17631@ovro.caltech.edu> <20090818205919.GA1168@ovro.caltech.edu> <4A8B1C7F.4060008@redhat.com> <20090819003812.GA11168@ovro.caltech.edu> <4A8B9051.3020505@redhat.com> <20090819152811.GA22294@ovro.caltech.edu> <4A8C1C22.3010101@redhat.com> <20090819162902.GB22294@ovro.caltech.edu> <4A8C2A87.5060305@redhat.com> <1250715920.4237.26.camel@slab.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Hollis Blanchard , "Ira W. Snyder" , "Michael S. Tsirkin" , Gregory Haskins , kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, alacrityvm-devel@lists.sourceforge.net, Anthony Liguori , Ingo Molnar , Gregory Haskins To: Stefan Hajnoczi Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 08/20/2009 12:57 PM, Stefan Hajnoczi wrote: > Cross-platform virtio works when endianness is known in advance. For > a hypervisor and a guest: > 1. virtio-pci I/O registers use PCI endianness > 2. vring uses guest endianness (hypervisor must byteswap) > 3. guest memory buffers use guest endianness (hypervisor must byteswap) > > I know of no existing way when endianness is not known in advance. > Perhaps a transport bit could be added to mark the endianness of the > guest/driver side. This can be negotiated because virtio-pci has a > known endianness. After negotiation, the host knows whether or not > byteswapping is necessary for structures in guest memory. > > Some processors are capable of switching their gender at runtime, so you cannot tell the guest endianness in advance. -- error compiling committee.c: too many arguments to function