Re: [9fans] VMX Cores

[hiro <23hiro@gmail.com>]

> i dont see vmx causing kernel crashes for me.
> however, i think the author meant to express is lack
> of confidence in the air-tightiness of vmx giving
> the zillions of architectual registers you have to
> setup to contain a guest. it is easy to forget
> to set some bit and everything works until someone
> manages to exploit that.

and not like any competitor has any great solution to that either. the
hardware just never was built for such strong isolation to
meaningfully prevent that kind of exploit. and if it did, there would
still always be other side-channels. just less obvious ones (from
today's pov).
in terms of stability, my slowlaris hypervisor (their own vmx plus
qemu) has finally reached some limit, which destroyed the guest
kernel's interpretation of time, which created some centuries of
timeshifting, waits don't fire any more, and suddenly i have 1000s
days of uptime bec. it's like a hundred years later now. forced me to
destroy this virtual computer and thus reboot the guest. :D stuff
breaks. everywhere. vmx is small, so actually it might break less in
some edge-cases. but yes, virtualization is one more layer, and the
interfaces, drivers, aren't as minimal as they could be, so
virtualization still sucks. even with all these hw optimizations now.
still a neat hack, i guess if you want to implement multi-core vmx, a
lot of firefox on vmx on plan9 users will be happy. otherwise, what do
we need that needs multiple cores in a vm?

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