Re: portability layer?

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Wednesday 28 March 2007, Hollis Blanchard wrote:
> > I don't see a big difference between the ioctl layer and libkvm.  In 
> > general, a libkvm function is an ioctl, and kvm_callback members are a 
> > decoding of kvm_run fields.  If you edit kvm_run to suit your needs, you 
> > can probably reuse some of it.
> 
> kvm_run as it stands is 100% x86-specific. (I doubt it could even be
> easily adapted for ia64, which is more similar to x86 than PowerPC.) So
> right now the kernel ioctl interface has an architecture-specific
> component, which violates the principle of identical interfaces I
> described earlier.

Remember that there _is_ an equivalent of kvm_run on powerpc (not powerpc64)
inside of MacOnLinux, though I could not find it now when looking through
the source.

> That means we either a) need to change the kernel interface or b) define
> a higher-level interface that *is* identical. That higher-level
> interface would be libkvm, hence my original question.
> 
> Does my original question make more sense now? If you make libkvm the
> official interface, you would at least need to hide the "cpuid"
> callback, since it is intimately tied to an x86 instruction.

If there is going to be an architecture independent interface, it
should really be able to cover s390 as well, which has yet other
requirements. It's probably closer to amd64 than to powerpc64 though.

	Arnd <><

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