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Re: [Xen-devel] [PATCH] 0/2 VCPU creation and allocation

On 10 Oct 2005, at 17:05, Ryan Harper wrote:

Do you even need a max_vcpus variable? Surely the appropriate check is
implicit in VCPUOP_initialise detecting whether or not the relevant
VCPU has been created?

I was going to ensure ordered VCPU creation.  Without something like
vcpuid < max_vcpus+1, and increment on successful creation, one can
create vcpus in any order, 1,5,7, 10.  I don't think it *should* matter
but I've not looked elsewhere through the code to see if there are any
other areas assuming all struct vcpu* being valid between 0 and n in
the d->vcpus[] array.

Then the vcpu parameter to VCPUOP_create is redundant -- there's only one value you will be prepared to accept! If we don't want the flexibility of a sparse vcpu map (and I think we don't) then perhaps we are better off without VCPUOP_create (which is maybe even a bit neater, leaving vcpu_op as a completely unpriv local hypercall) and stick with the set_max_vcpus dom0_op? And have that implicitly create the vcpu struct for vcpus 0...n-1?

 -- Keir

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