Re: hardwired VMI crap

Ingo Molnar
2007-03-08T21:36:05Z

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Zachary Amsden wrote:
> > We faithfully emulate lapic, io_apic, the pit, pic, and a normal
> > interrupt subsystem.
>
> Can you not just use the apic clock driver directly then? Do you need
> to do anything special?

exactly. There are only two variants Linux wants to care about:

- native hardware ABIs. If a hypervisor (like KVM) happens to do its
stuff based on those, more power to them - we dont (and cannot) care.

- /One/ _intelligent_ higher-level virtualization API/ABI. Xen's API is
quite advanced on this front. This would be shared by /all/
hypervisors and could occasionally be reused by other hardware
platforms as well. It can be morphed via small wrappers into some
'hypervisor personality' kind of hypervisor backends, but no
fundamental transformation happens.

what we do _NOT_ want is some mixture of 'simplified' and 'hardwired'
native hardware access mixed with hypercalls that somehow ends up
creating a Frankenstein mixture of 'virtual silicon', which is specified
nowhere else but in VMWare's proprietary hypervisor source code that we
have no way to fix and no way to even see!

it's hard enough to get native silicon support right.

Ingo