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

[Ryan Harper <ryanh@xxxxxxxxxx>]

* Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> [2005-10-10 11:13]:
> 
> 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?

OK, that makes sense.  I'll turn VCPUOP_create into set_max_vcpus(max)
which will create vcpus 1-(max-1).  Any preference on the hypercall
name?  Does set_max_vcpus() still make sense if it is also creating
vcpus?

How about DOM0_CREATEVCPUS and
    do_createvcpus(struct domain* d, unsigned int max_vcpus).

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@xxxxxxxxxx

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