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Date:      Tue, 04 Feb 1997 21:27:42 +0800
From:      Peter Wemm <peter@spinner.dialix.com>
To:        joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
Cc:        smp@FreeBSD.ORG
Subject:   Re: My first SMP kernel... 
Message-ID:  <199702041327.VAA15354@spinner.DIALix.COM>
In-Reply-To: Your message of "Tue, 04 Feb 1997 09:27:07 %2B0100." <Mutt.19970204092707.j@uriah.heep.sax.de> 

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J Wunsch wrote:
> As Steve Passe wrote:
> 
> > > lying around :).  I've also verified before that both CPUs have the
> > > `SSS' signature.
> > 
> > SSS? I don't see that in the list.
> 
> The numbers on the bottom lid end up in SSS.

SSS chips are theoretically the "best you can get".. ie: they don't need 
voltage twiddles etc to get them to work.

> >  what specifically are the exact
> > S-spec #s of each?
> 
> I have to look, they are at work (but i'm at home still).

What do you get on the dmesg output when booting a non-smp kernel?

CPU: Pentium (90.00-MHz 586-class CPU)
  Origin = "GenuineIntel"  Id = 0x521  Stepping=1
  Features=0x7bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8,APIC,<b10>>
[...]
npx0 on motherboard
npx0: INT 16 interface
npx0: Pentium floating point divide (fdiv) flaw present!

This comes from a very early batch of P5-90's.

> > one possibility for testing would be to get Peter to place a known working
> > kernel on freefall, then grab it & try, since your hardware is so similar.
> 
> Well, my question was rather whether i should basically mistrust that
> particular source tree (and re-roll that CD-ROM for the GUUG meeting
> again), or whether it's just a personal problem with my setup.  In the
> latter case, it's not really important, i've only dug up that old
> Neptune board for a simple test.  (It's our scratch machine at work,
> but there's usually only a single CPU in it, i have to ``borrow''
> another CPU from another machine for testing.)

I seem to recall dire warnings about mixing different stepping/S number 
chips from the early runs.. I believe the apic timing etc was tweaked a 
bit early on, but they now seem to have it sorted out..  But if one of the 
chips is old, you might be in for fun.

> What surprised me was that this SMP kernel crashed all over the place
> even on the board equipped with a single CPU only, while the
> kernel.GENERIC worked well with the very same hardware.

The SMP kernel is very out of date with respect to -current.  I believe 
it's missing some VM fixes from John Dyson.  Now that I've nearly finished 
moving house (argh, what a nightmare!) I must revisit this.  I don't think 
there are any fundamental differences, except for the MAXLOGNAME size bump 
(it's 12 in SMP, but 16 in -current with padding to make the structures 
compatable).  Hmm, I think I'd better import a new version before John 
strikes with the Lite2 merge in -current.. :-]

Cheers,
-Peter





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