Re: [PATCH 1/38] KVM: Create kvm-intel.ko module

From: Andrew Morton
Date: Thu Nov 30 2006 - 15:00:55 EST


On Thu, 30 Nov 2006 16:44:25 +0100
Ingo Molnar <mingo@xxxxxxx> wrote:

> > [...] Pretty similar to things like the msr or mtrr driver that expose
> > cpu features as character drivers aswell.
>
> you can expose everything as character drivers and ioctls, but that
> doesnt make it the right solution. It might /start out/ as a driver,
> because that's an easy to hack model, but the moment something becomes
> important enough (and virtualization certainly is such a model) it
> demands a system call.

Actually fourteen syscalls and counting, and some of those have `mode'
arguments.

It's a fat, complex, presumably arch-specific, presumably frequently-changing
API. So whatever we do will be unpleasant - that's unavoidable in this case,
I suspect.

(hmm, the interface isn't versioned at present - should it be?)

Maybe, perhaps, one day it _should_ be a syscall API. But right now if we
did that it would become a versioned syscall API with obsolete slots and
various other warts.

I get the feeling we'd be best off if we were to revisit this in a year or
so.

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