SMP system not running SMP

John Baldwin jhb at
Tue Jun 27 15:13:21 UTC 2006

> > What's bugging me is that, despite people having told me you can't have
> > SMP without ACPI, I thought I did the NetBSD test back when I had ACPI
> > disabled 
> I think what people are sayng is that ACPI is part of the spec for the 64
> bit platform. So you *shouldn't* do a 64 bit OS with ACPI disabled, and it's
> hardly surprising if you run into problems if you do. Under 32 bit (which is
> what I have reverted to trying) then ACPI is not part of the platform spec
> and is thus not needed for SMP (as SMP on 32 bit predates ACPI).
> So if you ran 32 bit NetBSD then it should work with or withough ACPI. If
> you run it as 64 bit's then it is well within it's right to fail if ACPI
> is disabled. On the other hand it might just share the 32 bit code and
> still work.
> That's my understanding - can someone correct me if the above is wrong ?

I think FreeBSD/amd64 doesn't include support for finding APICs w/o ACPI
(i.e. the MP Table from the BIOS) whereas FreeBSD/i386 does.  FreeBSD/amd64
really wants you to use ACPI (pretty much required).  This is why I want to ge 
things working on FreeBSD/i386 first as it includes the MP Table support.

John Baldwin

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