Re: [PATCH 0/6] Implement generic IPI support mechanism

Thomas Gleixner
2015-09-30T14:03:43Z

On Wed, 30 Sep 2015, Qais Yousef wrote:

> On 09/29/2015 09:48 PM, Thomas Gleixner wrote:
> >
> > Now how these hwirqs are allocated is a domain/architecture
> > specific issue.
> >
> > x86 will just find a vector which is available on all target
> > cpus and mark it as used. That's a single hw irq number.
> >
> > mips and others, which implement IPIs as regular hw interrupt
> > numbers, will allocate a these (consecutive) hw interrupt
> > numbers either from a reserved region or just from the
> > regular space. That's a bunch of hw irq numbers and we need
> > to come up with a proper storage format in the irqdata for
> > that. That might be
> >
> > struct ipi_mapping {
> > unsigned int nr_hwirqs;
> > unsigned int cpumap[NR_CPUS];
> > };
>
> Can we use NR_CPUS here? If we run in UP configuration for instance, this will
> be one. The coprocessor could be outside the NR_CPUS range in general, no?
>
> How about
>
> struct ipi_mapping {
> unsigned int nr_hwirqs;
> unsigned int nr_cpus;
> unsigned int *cpumap;
> }
>
> where cpumap is dynamically allocated by the controller which has better
> knowledge about the supported cpu range it can talk to?

Sure. As I said: 'That might be' ....

Thanks,

tglx