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Date:      Mon, 11 Jul 2005 08:55:13 +0200
From:      Nelis Lamprecht <>
To:        Drew Tomlinson <>
Cc:        FreeBSD Questions <>
Subject:   Re: FreeBSD 5 - What Options for SMP Kernel?
Message-ID:  <>
In-Reply-To: <>
References:  <>

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On 7/11/05, Drew Tomlinson <> wrote:
> I just built my first 5.4-RELEASE system.  I want a SMP kernel.  The
> GENERIC kernel conf file contains this line:
> device          apic                    # I/O apic
> According to NOTES, this is all that's required to build an SMP kernel.

I don't see any mention of "this is all that's required" ?

> However my dmesg does not indicate that both processors are being used.
> In version 4, these two lines were required:
> options        SMP                     # Symmetric MultiProcessor Kernel
> options        APIC_IO                 # Symmetric (APIC) I/O
> I've searched Google but haven't found any definitive answers.  Exactly
> what lines do I need in my kernel conf and how can I verify both
> processors are being used?

If you look in the usual place /usr/src/sys/i386/conf you will see a
SMP file that includes the option SMP for the default SMP enabled
GENERIC kernel. It would make sense to put that option along with apic
in your custom SMP kernel.

To verify after rebooting do a 'dmesg |grep CPU' and it should show
something along the lines of:

CPU: Intel(R) Xeon(TM) CPU 3.06GHz (3056.82-MHz 686-class CPU)
  Hyperthreading: 2 logical CPUs
FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs


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