Re: Xen & VMI?

Zachary Amsden
2007-03-07T02:16:27Z

Ingo Molnar wrote:

> We do not let OpenOffice or Evolution have its own separate ABI to Linux
> so that they 'can evolve at their own pace'... We want them to cooperate
> and come up with a common ABI (or rather, we try to come up with the
> right syscalls ourselves), because divering, overlapping ABIs are a huge
> PITA.
>

OpenOffice or Evolution are the completely wrong example. They disprove
your point more than they prove it. Consider any significantly large
cross-platform software like OpenOffice, Evolution, Firefox. You don't
let or restrict what these pieces of software do at all. They evolve at
their own pace, and they all build their very complicated and divergent
cross platform compatibility layers, with huge, overlapping APIs,
converging in places, diverging in others.

> We do not unify their pointlessly diverging ABIs to within the kernel
> via say office_ops (while we could) because that's crappy on its face.
> Hypervisors arent in any way different, they just _think_ they are
> special because they are relatively new. But hey, i dont expect you to
> concede this point ;)

No, you don't. The developers of Office and Evolution and Firefox do
that for you. And it's not crappy on its face because it provides real
value to them - the ability to run heterogeneously in multiple different
environments and across many different platforms and operating systems.

Where your analogy is wrong is that in this case, Linux is very much
like one of those large software systems. It has complicated features
that require special plugins to work efficiently in different hypervisor
environments. And paravirt-ops is providing that functionality to
Linux, just as the platform layer of any large software system does and
very much should do.

Zach