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

["Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>]

> > 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.

Agreed, but even with CPU hotplug there will be some max_pcpu value
on any given machine.  That's why I said "non-existent processor"
in the proposal even though you said "offline processor".

Dan


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