RE: [PATCH][2.5][RFC] Using xAPIC apic address space on !Summit

[Nakajima, Jun]

The clustering mode we are talking about is part of xAPIC functionality, not
a NUMA (or Multi-Quad) thing. Even a non-NUMA system, it's available if it
has xAPICs. 

Jun

> -----Original Message-----
> From: Zwane Mwaikambo [mailto:[e-mail]]
> Sent: Thursday, December 12, 2002 7:11 PM
> To: James Cleverdon
> Cc: Martin Bligh; John Stultz; Linux Kernel
> Subject: Re: [PATCH][2.5][RFC] Using xAPIC apic address space on !Summit
> 
> On Thu, 12 Dec 2002, James Cleverdon wrote:
> 
> > Sure you can physically address them, if you assign IDs using Intel's
> official
> > xAPIC numbering scheme (which must be clustered for more than 7 CPUs).
> But,
> > you still don't have enough destination address bits to go around.  In
> flat
> > mode, the kernel assumes you have one bit per CPU and phys IDs will be <
> 0xF.
> >
> > Bill tells me that you may be doing this for an emulator.  Why not
> emulate
> > clusered APIC mode, like the real hardware uses?
> >
> > I know the name x86_summit doesn't really fit.  The summit patch should
> work
> > for any xAPIC box that uses the system bus for interrupt delivery and
> has
> > multiple APIC clusters.  Is that what you're working towards?
> 
> Hmm although i could then skip the logical destination mode and stick to
> physical destination mode. This would greatly simplify my code paths since
> i could almost use the same code for both normal SMP and this larger sim.
> Debugging would then be somewhat simpler. My target doesn't have multiple
> APIC clusters and all are addressable via a 0xff broadcast.
> 
> Thanks,
> 	Zwane
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