Re: [RFC][PATCH] fix for clusterd io_apics

["Martin J. Bligh" <mbligh@aracnet.com>]

>   The following is a patch to fix inconsistent use of the function
> set_ioapic_affinity. In the current kernel it is unclear as to weather
> the value being passed to the function is a cpu mask or valid apic id. 
> In irq_affinity_write_proc the kernel passes on a cpu mask but the kirqd
> thread passes on logical apic ids.  In flat apic mode this is not an
> issue because a cpu mask represents the apic value.  However in
> clustered apic mode the cpu mask is very different from the logical apic
> id.  
>   This is an attempt to do the right thing for clustered apics.  I
> clarify that the value being passed to set_ioapic_affinity is a cpu mask
> not a apicid.  Set_ioapic_affinity will do the conversion to logical
> apic ids.  Since many cpu masks don't map to valid apicids in clustered
> apic mode TARGET_CPUS is used as a default value when such a situation
> occurs.  I think this is a good step in making irq_affinity clustered
> apic safe.

Thanks Keith, looks great. The existing code in the main kernel is just
broken (and confusing as hell with it's mixed use of "mask").

M.