freebsd-dev/release/doc/en_US.ISO8859-1/hardware/i386/proc-i386.sgml

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<sect1 id="proc">
  <title>Supported Processors and Motherboards</title>

  <para>&os;/i386 runs on a wide variety of
  <quote>IBM PC compatible</quote> machines.  Due to the wide range of
  hardware available for this architecture, it is impossible to
  exhaustively list all combinations of equipment supported by &os;.
  Nevertheless, some general guidelines are presented here.</para>

  <para>Almost all i386-compatible processors are supported.  All
  Intel processors beginning with the 80386 are supported, including
  the 80386, 80486, Pentium, Pentium Pro, Pentium II, Pentium III,
  Pentium 4, and variants thereof, such as the Xeon and Celeron
  processors.  (While technically supported, the use of the 80386SX is
  specifically not recommended.)  All i386-compatible AMD processors
  are also supported, including the Am486, Am5x86, K5, K6 (and variants),
  Athlon (including Athlon-MP, Athlon-XP, Athlon-4, and Athlon Thunderbird), and Duron processors.  
  The AMD &Eacute;lan SC520 embedded processor is supported.
  The Transmeta Crusoe is recognized
  and supported, as are i386-compatible processors from Cyrix and
  NexGen.</para>

  <para>There is a wide variety of motherboards available for this
  architecture.  Motherboards using the ISA, VLB, EISA, AGP, and PCI
  expansion busses are well-supported.  There is some limited support
  for the MCA (<quote>MicroChannel</quote>) expansion bus used in the
  IBM PS/2 line of PCs.</para>

  <para>Symmetric multi-processor (SMP) systems are generally
  supported by &os;, although in some cases, BIOS or motherboard bugs
  may generate some problems.  Perusal of the archives of the &a.smp;
  may yield some clues.</para>

  <para>&os; will take advantage of HyperThreading (HTT) support on
    CPUs that support this feature.  A kernel with the
    <literal>SMP</literal> feature enabled will detect and start the
    additional logical processors.  The default &os; scheduler treats
    the logical processors the same as additional physical
    processors; in other words, no attempt is made to optimize
    scheduling decisions given the shared resources between logical
    processors within the same CPU.</para>

  <para>&os; will generally run on i386-based laptops, albeit with
  varying levels of support for certain hardware features such as
  sound, graphics, power management, and PCCARD expansion slots.
  These features tend to vary in idiosyncratic ways between machines,
  and frequently require special-case support in &os; to work around
  hardware bugs or other oddities.  When in doubt, a search of the
  archives of the &a.mobile; may be useful.</para>
</sect1>