On 06.03.20 21:24, Alex Bennée wrote:
I suspect all of these multi-process models just hand wave away details
like migration because that really does benefit from a single process
with total awareness of the state of the system. That said I wonder how
robust a guest can be if the device emulation may go away at any time?
I guess in virtio if you never signal the consumption of a virt-queue it
will still be there waiting until you restart the emulation process and
pick up from where you left off?
The virtio spec seems be fine with individual backends dying. Recovery
depends on the hypervisor maintaining state for the backends - not sure
if that is easily doable, though.
But the challenge starts earlier: virtio-over-ivshmem is designed to
support independent backends lifecycles (and has no state except for
guest lifeness in the hypervisor). But while playing with that, I
immediately ran into Linux frontend code assuming that a virtio device
never dies (virtio console, IIRC). I suspect that there are more cases
in Linux, not to speak of other guests.
Jan
--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
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