From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Otte Subject: Re: [RFC] virtio-blk PCI backend Date: Tue, 20 Nov 2007 12:05:28 +0100 Message-ID: <4742BF78.7090400@de.ibm.com> References: <11944902733951-git-send-email-aliguori@us.ibm.com> <200711200939.19410.borntraeger@de.ibm.com> <4742B053.8080301@qumranet.com> <200711201117.17900.arnd@arndb.de> Reply-To: carsteno-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Avi Kivity , borntrae-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org To: Arnd Bergmann Return-path: In-Reply-To: <200711201117.17900.arnd-r2nGTMty4D4@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Arnd Bergmann wrote: > Not sure if I'm following the reasoning here. Shouldn't the method be > inherent to the virtio bus driver? > > When you use a PCI based virtio bus, the natural choice would be PIO > in some way, but you could also have a different virtio implementation > on PCI that uses hcalls. This choice is completely up to virtio-pci. > > On s390, you have a different virtio backend altogether, so you always > use DIAG or hcall instead of whatever virtio-pci does. > > The virtio-blk and other high-level drivers don't need to care about > what transport the bus uses in the first place. If you look at HPA's virtio PCI bus in lguest, it uses PCI device organization but no other PCI features. That's where we're heading, because we don't want a different virtio backend. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/