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Subject: Re: [virtio-comment] virtio and endian-ness
On Mon, 19 Aug 2013 16:05:43 +0300 "Michael S. Tsirkin" <firstname.lastname@example.org> wrote: > > One idea might be that all devices start out in 'legacy mode' and we > > add either a feature bit or a new channel command that switches to > > 'standard mode'. Old hosts would reject that command, while old guests > > would simply not issue it. > > > > Another idea is to look at the read_conf/write_conf channel commands > > and introduce a new pair of read_conf_le/write_conf_le commands. Again, > > compatibility would be achived via the host doing command rejects. > > > > We also have the possibility to convey extra information about the > > control unit (the device) in the 'extended sense id data' via the sense > > id command. Basically, we can encode some supported channel commands in > > there, but we would need a new command type for that architectured. > > We'd still need to rely on the command rejects mentioned above, though. > > If guest can discover whether host supports the new layout, > why would there be any rejects? If we want to support old guests on new hosts, we'll have to rely on this.