From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH/RFC 7/9] Virtual network guest device driver Date: Thu, 24 May 2007 01:02:40 +0200 Message-ID: <200705240102.40795.arnd@arndb.de> References: <8FFF7E42E93CC646B632AB40643802A8032793AC@scsmsx412.amr.corp.intel.com> <4653F807.2010209@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: Jimi Xenidis , Christian Borntraeger , jmk-zzFmDc4TPjtKvsKVC3L/VUEOCMrvLtNR@public.gmane.org, mschwid2-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, Christoph Hellwig , carsteno-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org, Suzanne McIntosh To: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Return-path: In-Reply-To: Content-Disposition: inline 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 Wednesday 23 May 2007, Eric Van Hensbergen wrote: > On 5/23/07, Carsten Otte wrote: > > > > For me, plan9 does provide answers to a lot of above requirements. > > However, it does not provide capabilities for shared memory and it > > adds extra complexity. It's been designed to solve a different problem. > > > As a point of clarification, plan9 protocols have been used over > shared memory for resource access on virtualized systems for the past > 3 years. =A0There are certainly ways it can be further optimized, but it > is not a restriction. I think what Carsten means is to have a mmap interface over 9p, not implementing 9p by means of shared memory, which is what I guess you are referring to. If you want to share memory areas between a guest and the host or another guest, you can't do that with the regular Tread/Twrite interface that 9p has on a file. > As far as complexity goes, our guest-side stack = > is around 2000 lines of code (with an additional 1000 lines of support > routines that could likely be replaced by standard library or OS > services in more conventional platforms) and supports console, file > system, network, and block device access. Another interface that I think is missing in 9p is a notification for hotplugging. Of course you can have a long-running read on a special file that returns the file names for virtual devices that have been added or removed in the guest, but that sounds a little clumsy compared to an specialized interface (e.g. Tnotify). Arnd <>< ------------------------------------------------------------------------- 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/