.\" Copyright (c) 1997
.\"	Steve Passe <fsmp@FreeBSD.ORG>.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. The name of the developer may NOT be used to endorse or promote products
.\"    derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\"
.\" $FreeBSD: src/share/man/man4/smp.4,v 1.7.2.4 2001/08/17 13:08:39 ru Exp $
.\"
.Dd August 17, 2013
.Dt SMP 4
.Os
.Sh NAME
.Nm SMP
.Nd description of the Symmetric MultiProcessor kernel
.Sh DESCRIPTION
The
.Dx
kernel implements symmetric multiprocessor support by default.
APIC I/O can be enabled or disabled by setting the
.Va hw.ioapic_enable
loader tunable to 1 or 0.
.Dx Ap s
default is to enable APIC I/O on real hardware and to disable it in
virtual machines, as determined by the VMM bit in the CPU features.
.Sh COMPATIBILITY
The
.Nm
kernel supports motherboards that follow the Intel MP specification,
version 1.4.
.Sh SEE ALSO
.Xr mptable 1 ,
.Xr dmesg 8
.Sh HISTORY
The
.Nm
kernel's early history is not (properly) recorded.  It was developed
in a separate CVS branch until April 26, 1997, at which point it was
merged into 3.0-current.  By this date 3.0-current had already been
merged with Lite2 kernel code.
.Pp
Starting with
.Dx 3.3 ,
the kernel has SMP support by default and it is no longer optional.
.Sh AUTHORS
.An Steve Passe Aq Mt fsmp@FreeBSD.org
.Sh BUGS
That would be a good guess...