On 2020/10/30 下午7:13, Stefan Hajnoczi wrote:
I still don't get why it must be opaque.
If the device state format needs to be in the VMM then each device
needs explicit enablement in each VMM (QEMU, cloud-hypervisor, etc).
Let's invert the question: why does the VMM need to understand the
device state of a_passthrough_ device?
It's not a 100% passthrough device if you want to support live
migration. E.g the device state save and restore is not under the
control of drivers in the guest.
And if I understand correctly, it usually requires device emulation or
mediation in either userspace or kernel to support e.g dirty page
tracking and other things.
Thanks
