Re: [Xen-devel] [PATCH v3 3/6] xen/arm: gic: Use the correct CPU ID

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Fri, 2013-09-20 at 16:58 +0100, Julien Grall wrote:
> On 09/20/2013 04:44 PM, Ian Campbell wrote:
> > On Fri, 2013-09-20 at 16:03 +0100, Julien Grall wrote:
> > 
> >> +static unsigned int gic_cpu_mask(const cpumask_t *cpumask)
> >> +{
> >> +    unsigned int cpu;
> >> +    unsigned int mask = 0;
> >> +    cpumask_t possible_mask;
> >> +
> >> +    cpumask_and(&possible_mask, cpumask, &cpu_possible_map);
> > 
> > Based on the other subconversation doesn't this need to be online_mask?
> > Or is the cpu area setup for cpus which are possible but not online?
> 
> cpu area is initialized a little bit before the cpu is bring up:
>   * initialize per cpu data (via the notifier_call_chain CPU_UP_PREPARE)
>   * signal the cpu to boot (__cpu_up)
>   ...
>   * call start_secondary
>       * initialize the gic cpu interface (gic_cpu_init)
>       * route ppis (which used gic_cpu_mask)
>       * set the cpu online
> 
> If we use the cpu online mask, Xen won't be able to route the different
> ppis to the processor.
> 
> > Should the check (whichever it is) be an assertion?
> 
> If we stay with the cpu_possible_map, I think we are fine without an
> assertion.

OK.

OOI where in the above is the cpu_possible_map setup? Quite a bit before
the CPU_UP_PREPARE hook I think? It shouldn't be a problem, just
interested...

Ian


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