On Fri, Jul 26, 2024 at 09:06:29AM +0100, David Woodhouse wrote: > That's great. You don't even need it to be per-vCPU if you let the > hypervisor write directly to the single physical location that's mapped > to userspace. It can do that before it even starts *running* the vCPUs > after migration. It's a whole lot simpler. It *seems* simpler, until you realize that there is no way to change anything in the interface, there is no negotiation between hypervisor and userspace. If I learned anything at all in tens of years working on software, it's that it is never done. So let's have userspace talk to the kernel and have kernel talk to the devices, please. There's no compelling reason to have this bypass here. -- MST
