On 2015/07/19 21:48, Michael S. Tsirkin wrote: > On Wed, Jun 24, 2015 at 07:57:45AM +0200, Michael S. Tsirkin wrote: >> On Wed, Jun 24, 2015 at 02:46:30PM +0900, Tetsuya Mukawa wrote: >>> On 2015/06/23 18:41, Michael S. Tsirkin wrote: >>>> On Tue, Jun 23, 2015 at 05:31:06PM +0900, Tetsuya Mukawa wrote: >>>>> On 2015/06/22 17:14, Michael S. Tsirkin wrote: >>>>>> On Mon, Jun 22, 2015 at 12:50:43PM +0900, Tetsuya Mukawa wrote: >>>>>>> Hi guys, >>>>>>> >>>>>>> Here are patches to add feature to start QEMU without vhost-user >>>>>>> backend. >>>>>>> Currently, if we want to use vhost-user backend, the backend must start >>>>>>> before >>>>>>> QEMU. >>>>>> Aren't you looking for something like xinetd? >>>>> It will help for restricting starting order, but not help for >>>>> reconnection of vhost-user backend. >>>> At this point, I suggest that we always connect at vm start. >>>> With that, you can add an option to reset the VM >>>> on backend disconnect. >>>> So >>>> - detect backend disconnect >>>> - reset and stop (notifying management) >>>> - reconnect or detect backend reconnect >>>> - proceed with boot >>>> >>>> As I tried to explain below, getting the full functionality >>>> will require guest driver changes. They aren't hard to get >>>> done, patches welcome. >>>> >>> Could you please let me know your thinking about using >>> DEVICE_NEEDS_RESET for vhost-user reconnection? >>> If it's works, I will try to submit it. >> DEVICE_NEEDS_RESET is hard to handle correctly in guest: >> you need to reconfigure a bunch of state, >> so far no one wrote the necessary support. > But yes, if you write the guest code, I think > it can work. > > We probably want a feature bit so host can know guest can > handle reconnections, but that's a minor detail, it > would be easy to add afterwards. >
Hi Michael, I appreciate for your suggestion. I will check the virtio-net driver of linux and the virtio-net device of QEMU to know how difficult to implement DEVICE_NEEDS_RESET. Regards, Tetsuya
