RE: [PATCH][2.4] generic support for systems with more than 8 CPUs (1/2)

[Pallipadi, Venkatesh]

> From: Martin J. Bligh [mailto:[e-mail]]
> > 1/2 : checking for xAPIC support in the system
> 
> OK, that looks pretty sane - one question:
> 
> > -		if ((clustered_apic_mode != CLUSTERED_APIC_XAPIC) &&
> > +		if (!xapic_support &&
> > +		    (clustered_apic_mode != CLUSTERED_APIC_XAPIC) &&
> 
> When does xapic_support differ from
> (clustered_apic_mode == CLUSTERED_APIC_XAPIC) ?
>

They are quite different. 
Infact CLUSTERED_APIC_XAPIC just means using physical APIC mode and is kind of a
misnomer as xAPIC doesn't necessariy mean physical APIC mode. 
xapic_support says whether xAPIC support is there or not. Then APICs 
can be configured either in physical or logical modes. I mainly need this as
with xAPIC support, we have:
- LAPIC and IOAPIC have there own name space, 
- max or 255 CPUS with 0xff as broadcast, as opposed to 0xf broadcast in case of no xAPIC

> Do you want to use a physical flat xapic mode for your stuff, or the
> same clustered physical mode as the Summit stuff? If the latter, then
> the new switch seems unnecessary ....

Now I am getting a bit confused here. I am using physical mode with no clustering
whatsoever. Thats what I felt even Summit was doing in 2.4.

Thanks,
-Venkatesh