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Date:      Thu, 12 Sep 1996 11:38:32 -0700 (MST)
From:      Terry Lambert <terry@lambert.org>
To:        smp@csn.net (Steve Passe)
Cc:        terry@lambert.org, peter@spinner.dialix.com, rv@groa.uct.ac.za, freebsd-smp@FreeBSD.org
Subject:   Re: Intel XXpress - some SMP benchmarks
Message-ID:  <199609121838.LAA07343@phaeton.artisoft.com>
In-Reply-To: <199609121823.MAA18695@clem.systemsix.com> from "Steve Passe" at Sep 12, 96 12:23:59 pm

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> >> One thing I'm not clear about from the IO apic docs yet is whether there 
> >> are 15 cpu's and 15 IO apic's, or whether there's a limit of 15 devices on 
> >> the APIC bus.
> >
> > 1 BP, 31 (AP | IO APIC) (2^5 == 32)
> 
> its a four bit register, where do you get 2^5, am I missing something?

Oh, ugh.  Sequent supports 32 processors.  I wonder how?

Corrected value:

1 BP, 15 (AP | IO APIC) (2^4 == 16)

> > You may want to disassemble your MP cold boot BIOS code to see about
> 
> I've been wondering about the issue of the MP table being in BIOS.  
> Traditionally this is ROM.  Do you think they just hardcode all this
> stuff, or really arbitrate numbers during boot and can 'modify' them in the
> BIOS area because it is really shadowed into RAM?

Some of the stuff has to be arbitrary... the cache writeback/writethrough
is enough to make me believe that.  It changes with CMOS settings.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.



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