Re: [Xen-devel] "cpus" config parameter broken?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 10/1/08 22:40, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> So modulo-izing the cpus parameter code will eliminate this
> case, but I still wonder if vcpu_set_affinity should reject any
> mask that has bits set beyond max_pcpu instead of silently
> ignoring those bits.  Seems like an accident waiting to happen
> and indeed I got bitten by it.
> 
> Which is why I proposed tightening the definition of all affinity
> masks (and strings representing masks) to "if you try to enable
> a bit in the cpumask that refers to a non-existent processor, you
> will get an error"

That doesn't play nicely with CPU hotplug (not supported yet, but could well
be in future) where the online_map could be continually changing. The model
I'm aiming for in Xen is to remember all the CPUs requested by the
toolstack, but only schedule onto the subset that are actually online right
now (obviously). The implementation of this is of course quite simple given
the CPU hotplug is not supported right now.

 -- Keir



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