From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 0/5] KVM paravirt_ops implementation Date: Wed, 20 Jun 2007 14:39:43 -0700 Message-ID: <46799E9F.4020405@zytor.com> References: <4675F462.1010708@codemonkey.ws> <4675F9DE.6080806@goop.org> <4675FDCA.4040006@codemonkey.ws> <4676084F.3090901@goop.org> <46787325.30804@vmware.com> <4679381E.9090404@codemonkey.ws> <46794899.6070708@goop.org> <46798174.2060304@vmware.com> <46798597.4020903@codemonkey.ws> <4679882B.7070605@vmware.com> <46798C99.8010303@codemonkey.ws> <46799001.5020807@vmware.com> <46799716.9040402@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <46799716.9040402-TSDbQ3PG+2Y@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 To: Jeremy Fitzhardinge Cc: Zachary Amsden , kvm-devel , James Bottomley , virtualization List-Id: virtualization@lists.linuxfoundation.org Jeremy Fitzhardinge wrote: > >> The completely identical device model is of course ideal, but the >> implementation and consolidation of that is a long term prospect to >> move towards, not something that will happen immediately. We at least >> emulate physical hardware devices already, and will continue to need >> drivers compatible with those models for some time. > > Well, physical devices and completely emulated physical devices are > fairly straightforward - do it like real hardware. Its the semi-virtual > devices which pose problems. Either device emulations with a bit of > performance paravirtualization sprinkled over them, or virtualization > friendly devices which allow safe direct guest access, but need some > paravirtual management interfaces as well. > Those can still be detected by appearing in the PCI configuration space, though. It doesn't mean they actually have to emulate a PCI device. One of the "nice" things (from a virtualization perspective) is that there isn't a pan-architectural way to get to PCI config space, so on platforms where PCI is irrelevant, it can be implemented as a virtualization call. Multistandard devices obviously need to model real hardware more accurately, since that's the common denominator. -hpa ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/