> Or are they just saying that the VM my binary runs on might be some predictable Linux version, but the underlying thing launching the VM could be anything? Y

> Or are they just saying that the VM my binary runs on might be some predictable Linux version, but the underlying thing launching the VM could be anything? Yup. eg with Xen the hypervisor wasn't Linux, even if the privileged management VM (dom0) was Linux (or optionally NetBSD in the early days). The very small Xen hypervisor running on the bare metal was not a general purpose OS, and didn't expose any interface itself - it was well hidden and relied on dom0 for administration.