From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Guyader Subject: Re: [RFC][PATCH 0/5] Add V4V to Xen Date: Thu, 28 Jun 2012 11:19:57 +0100 Message-ID: <20120628101957.GA7935@spongy> References: <20120607114031.GP70339@ocelot.phlegethon.org> <20120607153657.GX70339@ocelot.phlegethon.org> <20120613104858.GC23207@boiler.cam.xci-test.com> <20120613114427.GA21809@ocelot.phlegethon.org> <20120614145608.GG90181@ocelot.phlegethon.org> <20120614151043.GB24063@spongy> <20120614153556.GI90181@ocelot.phlegethon.org> <20120625090537.GC1488@ocelot.phlegethon.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <20120625090537.GC1488@ocelot.phlegethon.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Tim Deegan Cc: Ian Campbell , Jean Guyader , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 25/06 10:05, Tim Deegan wrote: > At 22:14 +0100 on 14 Jun (1339712061), Jean Guyader wrote: > > On 14 June 2012 16:35, Tim Deegan wrote: > > > At 16:10 +0100 on 14 Jun (1339690244), Jean Guyader wrote: > > >> On 14/06 03:56, Tim Deegan wrote: > > >> > At 11:55 +0100 on 14 Jun (1339674908), Jean Guyader wrote: > > >> > > Are you talking about having different version of V4V driver run= ning > > >> > > in the same VM? > > >> > > > >> > Yes. > > >> > > > >> > > I don't think that is a problem they both interact with Xen via > > >> > > hypercall directly so if they follow the v4v hypercall interface= it's > > >> > > all fine. > > >> > > > >> > AFAICS if they both try to register the same port then one of them= will > > >> > silently get its ring discarded. =A0And if they both try to commun= icate > > >> > with the same remote port their entries on the pending lists will = get > > >> > merged (which is probably not too bad). =A0I think the possibility= for > > >> > confusion depends on how you use the service. =A0Still, it seems b= etter > > >> > than the xenstore case, anyway. :) > > >> > > > >> > > >> Not silently, register_ring will return an error. > > > > > > Will it? =A0It looks to me like v4v_ring_add just clobbers the old MFN > > > list. > > > > > = > > Ha yes. It does that now but I think it should return an error > > informing up the stack that a ring has already been registered. > = > Actually, I think it's deliberate, to allow a guest to re-register all > its rings after a suspend/resume or migration, without having to worry > about whether it was actually migrated into a new domain or not. = > = Yes your are right. The driver will still try to register but a correct err= or code could tell it weather or not it has been done. > That raises the question of how a v4v client ought to handle migration; > doesn't it have to rely on other OS components to notify it that one has > happened? > Migration will cause the connection to close and the event will propagated up the stack. Jean