use virtio-vsock to communicate with hyperstart

[bergwolf]

virtio-vsock (http://qemu-project.org/Features/VirtioVsock) was introduced as a communication device between host and guest. runv and hyperstart can use it to replace current serial port communication method.

[feiskyer]

@bergwolf Which version of qemu supports this?

[bergwolf]

@feiskyer none... It only exists in Stephan's qemu repo (https://github.com/stefanha/qemu/tree/vsock), and corresponding kernel support is still under development (got merged on Dec 3, 2015 torvalds/linux@c402293 and reverted on Dec 9, 2015 torvalds/linux@8ac2837)

Maybe we should reconsider it later when the code gets more stability.

[bergwolf]

The delay was due to a missing feature that virtio-vsock needs to allow only host to make the connection. See https://lists.linuxfoundation.org/pipermail/virtualization/2015-December/030913.html

[bergwolf]

close via #411