From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60220) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wv2fn-0006BF-1T for qemu-devel@nongnu.org; Thu, 12 Jun 2014 06:56:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wv2fc-0006Of-TV for qemu-devel@nongnu.org; Thu, 12 Jun 2014 06:55:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54524) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wv2fc-0006OC-7H for qemu-devel@nongnu.org; Thu, 12 Jun 2014 06:55:48 -0400 Date: Thu, 12 Jun 2014 13:56:10 +0300 From: "Michael S. Tsirkin" Message-ID: <20140612105610.GG22230@redhat.com> References: <5384A8D2.8050104@redhat.com> <20140529111253.4ff55199@bahia.local> <538708FA.4070309@redhat.com> <20140612094351.6295fd38@bahia.local> <53996B0E.4040808@redhat.com> <20140612110601.3fe5626e@bahia.local> <539970B3.3040304@redhat.com> <20140612093712.GA22565@redhat.com> <5399755E.10902@redhat.com> <53997638.6020403@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53997638.6020403@suse.de> Subject: Re: [Qemu-devel] [PATCH RFC 8/8] virtio: add endian-ambivalent support to VirtIODevice List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: Kevin Wolf , Fam Zheng , Anthony Liguori , Juan Quintela , qemu-devel@nongnu.org, Stefan Hajnoczi , Amit Shah , Paolo Bonzini , Andreas =?iso-8859-1?Q?F=E4rber?= , Greg Kurz On Thu, Jun 12, 2014 at 11:43:20AM +0200, Alexander Graf wrote: > > On 12.06.14 11:39, Paolo Bonzini wrote: > >Il 12/06/2014 11:37, Michael S. Tsirkin ha scritto: > >>Maybe just drop unnecessary stuff for new machine types? > >>Then we won't need hacks to migrate it. > > > >For any machine type it's trivial to migrate it. All machine types > >including old ones can disregard the migrated values. > > How about a patch like this before the actual LE awareness ones? With this > we should make virtio-serial config space completely independent of live > migration. > > Also since QEMU versions that do read these swapped values during migration > are not bi-endian aware, we can never get into a case where a cross-endian > save needs to be considered ;). > > > Alex > > > diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c > index 2b647b6..73cb9b7 100644 > --- a/hw/char/virtio-serial-bus.c > +++ b/hw/char/virtio-serial-bus.c > @@ -670,6 +670,7 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, > int version_id) > uint32_t max_nr_ports, nr_active_ports, ports_map; > unsigned int i; > int ret; > + uint32_t tmp; > > if (version_id > 3) { > return -EINVAL; > @@ -685,17 +686,12 @@ static int virtio_serial_load(QEMUFile *f, void > *opaque, int version_id) > return 0; > } > > - /* The config space */ > - qemu_get_be16s(f, &s->config.cols); > - qemu_get_be16s(f, &s->config.rows); > - > - qemu_get_be32s(f, &max_nr_ports); > - tswap32s(&max_nr_ports); > - if (max_nr_ports > tswap32(s->config.max_nr_ports)) { > - /* Source could have had more ports than us. Fail migration. */ > - return -EINVAL; > - } > + /* Unused */ > + qemu_get_be16s(f, &tmp); > + qemu_get_be16s(f, &tmp); > + qemu_get_be32s(f, &tmp); > > + max_nr_ports = tswap32(s->config.max_nr_ports); > for (i = 0; i < (max_nr_ports + 31) / 32; i++) { > qemu_get_be32s(f, &ports_map); > Exactly. Reviewed-by: Michael S. Tsirkin