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Date:      Thu, 30 Jul 1998 11:07:07 -0600
From:      Steve Passe <smp@csn.net>
To:        rv@plig.net
Cc:        mike@smith.net.au (Mike Smith), freebsd-smp@FreeBSD.ORG
Subject:   Re: SMP on dual porcessor Compaq 
Message-ID:  <199807301707.LAA28320@Ilsa.StevesCafe.com>
In-Reply-To: Your message of "Thu, 30 Jul 1998 11:49:24 BST." <199807301049.LAA05913@riffraff.plig.net> 

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Hi,

> > > My first guess would be this:
> > > > Processors: APIC ID Version State           Family  Model   Step    Flags
> > > >              0       0x10    BSP, usable     6       2       1       0x0381
> > > >              0       0x10    AP, usable      6       3       4       0x80fbff
> > > 
> > > You can't have two processors with the same ID.  I'd check to see what
> > > the flags mean, too.
> > 
> > I'd also be worried about the model mismatch, and the steppings; Intel
> > normally recommend only pairing processors at most one apart from each
> > other in stepping numbers.
> 
> Just tried swapping various combinations of processors (we have 2 of
> the machines) and I get the exact same result. All 4 processors tested
> are PII-266's and there are 2 pairs with each pair from the same
> manufacturer and only slight differing serial numbers.

The problem is definately the APIC ID of 0 for both CPU's, until you fix
that nothing else is going to help.

Others have encountered this ID clash between CPU and IO APIC ID's but I
have never seen a clash between CPUs before.  See section 3.6.6 of the 1.4
MP spec.  In this case the OS (ie FreeBSD) MUST reassign one of the CPU IDs
to another value.  I would assign the AP to value 1.

A quick hack could be made in sys/i386/i386/mp_machdep.c:processor_entry(),
reprogramming the AP at the point its encountered.

A clean fix would be to analyze the list of all APIC IDs immediately after
mptable_pass2(), adjusting both parts and table entries as appropriate.

--
Steve Passe	| powered by 
smp@csn.net	|            Symmetric MultiProcessor FreeBSD



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