On 24 January 2013 14:55, Stefan Hajnoczi <stefa...@gmail.com> wrote:
> On Thu, Jan 24, 2013 at 11:40:24AM +0530, Anup Patel wrote: > > IMHO, If we have something like Virtio-desktop specification then all > > possible guest OSes can have support for it and different hypervisor can > > emulate it without worrying about guest support. > > At this point x86 virtualization is mature and working with a mix of > emulated x86 architecture pieces and virtio devices for > performance-critical or open-ended functionality that we want to be able > to extend. > > ARM is getting KVM and virtio-mmio support. It will be in a similar > position soon. > > Virtio guest drivers have not been implemented widely. The Linux and > Windows efforts are driven by the folks who were behind virtio from the > start, but Solaris, FreeBSD, and others didn't really jump on the virtio > bandwagon. > [Anup] I think other OSes will be motivated to added Virtio drivers if there exists some think like Virtio-desktop specification that is being emulated by many hypervisors. > Given this landscape, what is the advantage of doing a virtio-desktop? > It will still need to fall back on ARM or x86 which is already being > virtualized and emulated. > [Anup] Virtio-desktop stresses on having minimum architecture dependent devices. Any improvements or additions in Virtio-desktop will be available to other architectures. > > Depending on how you see it we either have virtio-desktop already or, > if not, I think the experience with virtio adoption suggests other > hypervisors and guest OSes will not trip over themselves to implement > virtio-desktop. > [Anup] I believe Virtio adoption will increase by having a concrete Virtio-desktop specification and without it Virtio devices are just another way of para-virtualization. In fact, having Virtio-desktop support for an OS will enable it to run under different hypervisors. > What's the advantage over virtualizating an existing ARM or x86 platform > and using virtio devices where appropriate? > [Anup] With Virtio-desktop, many platforms can share lot of common code mostly in-form of Virtio devices. We already drivers for most Virtio devices in the mainline Linux kernel. The only missing devices are Virtio-fb, Virtio-input, and Virtio-power from Virtio-desktop perspective. [Anup] Further, Virtio is interface independent which means a Virtio device can be a MMIO-based device or PCI-based device or some other form. [Anup] Most proprietary hypervisors and Xen already have para-virtualized devices which are similar to Virtio devices. In fact, we have wide variety of approaches in para-virtualization. We can think of Virtio and Virtio-desktop as an attempt to standardize para-virtualization in an architecture independent and hypervisor independent way. Of-course, implementation and performance of Virtio devices will vary under different hypervisors. > > Stefan > --Anup
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