On Mon, Sep 21, 2015 at 02:32:10PM +0200, Jan Kiszka wrote: > On 2015-09-21 14:13, Michael S. Tsirkin wrote: > > On Fri, Sep 18, 2015 at 06:29:27PM +0200, Claudio Fontana wrote: > >> Hello, > >> > >> this is a first RFC for virtio-peer 0.1, which is still very much a work in progress: > >> > >> https://github.com/hw-claudio/virtio-peer/wiki > >> > >> It is also available as PDF there, but the text is reproduced here for commenting: > >> > >> Peer shared memory communication device (virtio-peer) > >> > >> General Overview > >> > >> (I recommend looking at the PDF for some clarifying pictures) > >> > >> The Virtio Peer shared memory communication device (virtio-peer) is a > >> virtual device which allows high performance low latency guest to > >> guest communication. It uses a new queue extension feature tentatively > >> called VIRTIO_F_WINDOW which indicates that descriptor tables, > >> available and used rings and Queue Data reside in physical memory > >> ranges called Windows, each identified with an unique identifier > >> called WindowID. > > > > So if I had to summarize the difference from regular virtio, > > I'd say the main one is that this uses window id + offset > > instead of the physical address. > > > > > > My question is - why do it? > > > > All windows are in memory space, are they not? > > > > How about guest using full physical addresses, > > and hypervisor sending the window physical address > > to VM2? > > > > VM2 can uses that to find both window id and offset. > > > > > > This way at least VM1 can use regular virtio without changes. > > What would be the value of having different drivers in VM1 and VM2, > specifically if both run Linux? > > Jan It's common to have a VM act as a switch between others. In this setup, there's value in being able to support existing guests as endpoints, with new drivers only required for the switch. > -- > Siemens AG, Corporate Technology, CT RTC ITP SES-DE > Corporate Competence Center Embedded Linux _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
