From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [Xen-devel] [PATCH RFC 1/3] virtio infrastructure Date: Tue, 05 Jun 2007 11:44:52 +1000 Message-ID: <1181007892.25878.112.camel@localhost.localdomain> References: <1180613947.11133.58.camel@localhost.localdomain> <08CA2245AFCF444DB3AC415E47CC40AFBD2CCF@G3W0072.americas.hpqcorp.net> <1180779167.9228.66.camel@localhost.localdomain> <08CA2245AFCF444DB3AC415E47CC40AFBD2FD4@G3W0072.americas.hpqcorp.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Jimi Xenidis , Stephen Rothwell , Xen Mailing List , jmk-zzFmDc4TPjtKvsKVC3L/VUEOCMrvLtNR@public.gmane.org, Herbert Xu , kvm-devel , virtualization , Christian Borntraeger , Suzanne McIntosh , Martin Schwidefsky To: "Santos, Jose Renato G" Return-path: In-Reply-To: <08CA2245AFCF444DB3AC415E47CC40AFBD2FD4-VylnnfFjWmASZAcGdq5asR6epYMZPwEe5NbjCUgZEJk@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 On Mon, 2007-06-04 at 21:14 +0000, Santos, Jose Renato G wrote: > Thanks for clarifying your thinking. This helped me understand > your goals better. > I agree it would be nice to reduce the number of drivers as it > improves mantainability. However I am not convinced that > adding an IO virtualization layer will remove the need > for having different drivers for different virtualization > technologies. > It seems that we will still need specific devices drivers > for each different virtualization flavor. For example, > we will still need to have a specific Xen netfront > device that talks to a backend device in dom0, using > page grants, and other Xen specific mechanisms. Hi Renato, That definitely should be implementable as a virtio layer; it was one of the design points. I consulted with Herbert Xu early on in the process, and I don't think it would be too painful. The devil, of course, is in the details. > It looks like will still need to maintain all the virtual device > drivers and in addition we will now have to maintain > another virtualization layer. That would be silly, yes. > I confess I don't know well any of the other virtualization > technologies besides Xen. Maybe for some of them there is > enough similarities that you could benefit from a common > virtualization layer, but I just can't see it yet. Well, S/390, PowerPC and UML both have virtual I/O already in the kernel tree, as does Xen. I believe VMWare have out-of-tree drivers. KVM is in tree, but currently doesn't have paravirtualized drivers. lguest is sitting in the -mm tree for merging in 2.6.23 with its own drivers. None of these drivers is optimal. The Xen ones are closest, and they're very Xen-specific and quite complex. This is good, and as it gives virtio drivers a target to beat 8) Cheers, Rusty. ------------------------------------------------------------------------- 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/