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 -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux
