Re: [Xen-users] How are CPU's presented to DomU's?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> We have some Windows HVM domains, and I am going to install some
> software that is licensed by the processor. The physical machine has 2 x
> Dual core processors, so in theory I should be able to give the virtual
> machine access to 1 physical processors worth of CPU (eg 2 cores) and
> only use a single processor license (Microsoft allows this on a physical
> dual core processor), but I'm curious as to how the processors show up
> in a DomU, whether they will be seen a 2 single cores or 1 dual core...

I'd suspect them to show up as 2 single cores but maybe the VCPU code is 
cleverer than I thought...

I guess the thing is that unless you pin the domain to only run on the cores 
of one package then it could potentially occasionally being run on multiple 
packages (albeit only on one core of each!).  I'm not sure there's a 
straightforward semantics for what this should look like to a guest where 
per-package licensing is being used!

Of course, in principle as it's a virtual machine you can probably make things 
appear to the guest any way you please by hacking on the code.  It just won't 
necessarily please MS ;-)

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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