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\input texinfo  @c -*- texinfo -*-
@c %**start of header
@setfilename options.info
@settitle Configuration Options for FreeBSD
@c @setchapternewpage odd
@c function index is option/pseudo/device names; concept is everything
@c else
@syncodeindex fn cp
@finalout
@c %**end of header

@ifinfo
$Id: options.texi,v 1.5 1994/02/27 18:57:47 wollman Exp $

This file documents the configuration options available in the FreeBSD
operating system.

@display
Copyright @copyright{} 1993, 1994, Garrett A. Wollman.  All rights reserved.

Redistribution and use in source and printed 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 and this list of conditions.
2. Redistributions in printed form must reproduce the above copyright
   notice, this list of conditions and the following notice of
   authorship.

Trademarks are property of their respective owners.
@end display
@end ifinfo

@titlepage
@title Configuration Options in FreeBSD
@subtitle for FreeBSD 1.1
@author Garrett A. Wollman
@author FreeBSD Project

@page
@vskip 0pt plus 1filll

i386, i387, and i486 are trademarks of Intel Corporation.  SunOS is a
registered trademark and NFS is a trademark of Sun Microsystems, Inc.
Ultrix is a registered trademark of Digital Equipment Corporation.
Xerox is a registered trademark and XNS is a trademark of Xerox
Corporation.  VESA is a trademark of the Video Electronics Standards
Association.  System V is a registered trademark of Novell Corporation.
All other trademarks are property of their respective owners.  FreeBSD
is nobody's trademark, and damn proud of it.

Copyright @copyright{} 1993, 1994, Garrett A. Wollman.  All rights reserved.

Redistribution and use in source and printed forms, with or without
modification, are permitted provided that the following conditions
are met:

@enumerate
@item
Redistributions of source code must retain the above copyright
notice and this list of conditions.

@item
Redistributions in printed form must reproduce the above copyright
notice, this list of conditions and the preceding notice of
authorship.
@end enumerate
@end titlepage

@node Top, Subsystems, (dir), (dir)
@top FreeBSD Configuration Options

This document describes kernel configuration options relevant to the
FreeBSD operating system version 1.1.  It is intended for readers who
already have a general understanding of the process of configuring a BSD
kernel and wish to get a general overview of the meaning of various
configuration options.  This document covers configurable options and
pseudo-devices; it is intended that devices may be added at a later
date.

@menu
* Subsystems::          Controlling subsystems.
* Performance::         Performance enhancement.
* Devices::             Device-control options.
* Internals::           Non-user-serviceable parts.

* Index::               General Index.
@end menu

@node Subsystems, Performance, Top, Top
@c node,next,prev,up

@chapter Options for Subsystems

This chapter discusses options controlling the inclusion of various
subsystems in FreeBSD.  These include things like filesystems,
networking modules, and whatnot.  Remember that options containing
underscores must be quoted.

@table @code
@item pseudo-device bpfilter @var{number}
@findex bpfilter
@cindex Berkeley packet filter
@cindex Network interfaces
The @samp{bpfilter} pseudo-device is the Berkeley Packet Filter,
developed by Lawrence Berkeley Labs and based on an earlier packet
filter from Stanford.  See the @samp{bpf} manual page for more details.
The @var{number} given is the maximum number of simultaneous users
permitted.  (NB: in previous version of BPF, the @var{number} had to be
greater than the number of interfaces; this space is now dynamically
allocated so this requirement is no longer present.)

@item options CCITT
@findex CCITT
@cindex X.25
@cindex Networking domains
The @samp{CCITT} option enables support for the ITU-T X.25(1980)
network-layer protocol.  Nobody we know has a direct X.25 connection to
anything, so this code has never been tested.

@item options "COMPAT_42"
@findex COMPAT_42
@cindex UDP Checksums
@cindex Checksums, UDP
@cindex 4.2 Compatibility
@cindex Compatibility options
This option is used to disable UDP checksumming.  Under ordinary
circumstances it should never ever ever be defined; however, if you are
stuck trying to communicate with an old 4.2BSD machine, or one running
something derived from 4.2 like SunOS 3.5 or Ultrix 2.0, this may be
necessary in order to successfully receive UDP packets.

@item options "COMPAT_43"
@findex COMPAT_43
@cindex 4.3 Compatibility
@cindex Compatibility options
This option controls a whole host of features, mostly relating to
system-call compatibilty with 4.3BSD.  At the present time, it should
not be turned off, as many utilities and library routines still depend
on these obsolescent system calls being present.  At some future date,
this will probably be split up into two separate options, one for binary
compatibility and one for the old but useful system calls.

@item options "DIRECTED_BROADCAST"
@findex DIRECTED_BROADCAST
@cindex IP
@cindex UDP
If this option is enabled, the kernel will support sending IP broadcast
packets to subnets other than the one that the machine is on, and when
forwarding will accept such packets.  That is to say, if your host lives
on subnets @samp{132.198.3} and @samp{132.198.4}, and the
@samp{132.198.3} side receives a packet addressed to
@samp{132.198.4.255}, it will forward the packet as a broadcast on that
subnet.

@item pseudo-device ether
@findex ether
@cindex Ethernet
@cindex Network interfaces
This pseudo-device provides link-layer support for Ethernet device
drivers.  It is mandatory for all systems which include Ethernet or
Ethernet-like devices, such as @samp{ed}, @samp{ie}, and @samp{is}.
This code is due for a redesign.

@item options EON
@itemx pseudo-device eon
@findex EON
@cindex ISO 8473 CLNP
@cindex Network interfaces
The @samp{eon} network interface supports the ISO 8473
Connectionless-Mode Network Protocol, tunnelled through IP version 4.
@samp{eon} interfaces are created automatically once initially
configured by adding ISO routes with IP destinations.  At present, both
the pseudo-device and option declaration are necessary.

@item options FIFO
@findex FIFO
@cindex Named pipes
This option enables support for System V-- and POSIX-style named pipes
or fifos.

@item options GATEWAY
@itemx options IPFORWARDING=@var{value}
@itemx options IPSENDREDIRECTS=@var{value}
@findex GATEWAY
@findex IPFORWARDING
@findex IPSENDREDIRECTS
@cindex ICMP
@cindex IP
@cindex Network parameters
These three options control whether FreeBSD's IP forwarding functions
are enabled.  Technically speaking, because FreeBSD does not meet the
standards set out in the ``Router Requirements'' document (RFC 1009),
these should not be enabled, but sometimes it is necessary to enable
this function.  The @samp{GATEWAY} option turns on @samp{IPFORWARDING},
and also controls the sizing of certain system tables.  The
@samp{IPFORWARDING} option controls the initial value of the
@samp{ipforwarding} kernel variable (default 1 if @samp{GATEWAY}
defined, 0 otherwise), which controls whether packets are acutally
forwarded or not; @var{value} should be either @samp{0} or @samp{1}.
@samp{IPSENDREDIRECTS} controls the initial value of the
@samp{ipsendredirects} variable (default is one, but should be changed
to zero); its @var{value} should also be either @samp{0} or @samp{1}.

@item options INET
@findex INET
@cindex IP
@cindex TCP
@cindex UDP
@cindex ICMP
@cindex Networking domains
This option controls the inclusion of the Internet protocol suite,
including IP version 4, TCP, UDP, and ICMP.  Support for IP multicast,
IP next generation, and IGMP will be provided at a future date.  It is
not recommended to even attempt to generate a system with this option
turned off, as many parts of the system depend on Internet networking in
important and subtle ways.

@item options ISO
@itemx options TPIP
@findex ISO
@findex TPIP
@cindex ISO 8473 CLNP
@cindex ISO TP4
@cindex ISO TP0
@cindex ISO 9542 ESIS
@cindex IEEE 802.2 LLC
@cindex Networking domains
These options control the inclusion of ISO OSI networking protocols.
The TPIP option includes just enough support to run ISO Transport
Protocol class 4 over IP, supporing the @samp{SOCK_SEQPACKET}
abstraction.  The ISO option includes support for CLNP, TP class 0,
ISO 9542 ESIS, and IEEE 802.2 logical link control class 0 (for CLNP only).

@item options ISOFS
@findex ISOFS
@cindex ISO 9660 filesystem
@cindex CD-ROM
@cindex Rock Ridge filesystem
@cindex Filesystems
The @samp{ISOFS} option enables kernel support for the ISO 9660 CD-ROM
filesystem, including RockRidge extensions.

@item options "ISO_X25ESIS"
@findex ISO_X25ESIS
@cindex ISO 9542 ESIS
@cindex X.25
This option controls whether ISO 9542 ESIS is run over ITU-T X.25 link
layers.  This requires the @samp{CCITT} option to be enabled as well.

@item options KTRACE
@findex KTRACE
@cindex Kernel tracing
This option enables the tracing of several classes of internal kernel
events.  See the @samp{ktrace} command for more details.

@item pseudo-device log
@findex log
@cindex Kernel message logging
The @samp{log} pseudo-device provides kernel support to send kernel
messages to @samp{syslog}.  It is mandatory.

@item pseudo-device loop
@findex loop
@cindex Network interfaces
The @samp{loop} pseudo-device provides the trivial network interface.
It is required when any networking options are enabled.

@item options MACHVMCOMPAT
@findex MACHVMCOMPAT
@cindex Mach virtual memory
This option enables a Mach-compatible interface to the virtual memory
subsystem, supporting system calls @samp{vm_allocate},
@samp{vm_deallocate}, @samp{vm_inherit}, and @samp{vm_protect}.
(Given the nature of the VM system, it is impossible to support a
Mach-style @samp{vm_region} call, and in every case the `map' argument
is ignored and replaced with the calling process's own map.)

@item options MFS
@findex MFS
@cindex Memory filesystem
@cindex Filesystems
This option enables support for the memory filesystem, an in-core
filesystem which lives in the swap area.  Using MFS as a @file{/tmp}
filesystem can dramatically increase the speed of
temporary-space-intensive operations such as compilations.  See the
@samp{mount_mfs} manual page for more details.

@item options NFS
@findex NFS
@cindex Network File System
@cindex Filesystems
The @samp{NFS} option enables support for Sun's Network File System.
(Also called ``Nightmare'' or ``Not a''@dots{}.)  This presently includes
both client-- and server-side kernelized NFS support; it may in the
future be broken into separate options.  This NFS implmentation comes to
BSD courtesy of Rick Macklem of the University of Guelph, and is not
derived from Sun licensed source code.  As a result, there are sometimes
interoperability problems where the published specification is vague,
and this option supports several new and useful features compared to
Sun's.  See the @samp{mount} manual page for more details.

@item options NS
@itemx options NSIP
@findex NS
@findex NSIP
@cindex Xerox Network System
@cindex XNS IDP
@cindex XNS SPP
@cindex Network interfaces
@samp{NS} controls the inclusion of support for the Xerox Network
Service protocol family.  At the present time, it is not known whether
this code even works; testers are welcome.  The @samp{NSIP} option
enables encapsulation of XNS IDP over IP.

@item options PANICDELAY
@itemx options PANICWAIT
@findex PANICDELAY
@findex PANICWAIT
@cindex Kernel panics
These options control whether the system waits after a panic.  This is
necessary on some systems which do not support crash dumps, so that the
actual panic message can be read.  The @samp{PANICDELAY} option inserts
a delay of twenty seconds before self-destructing; the @samp{PANICWAIT}
option instead waits for a key to be pressed on the console.

@item options PCFS
@findex PCFS
@cindex MS-DOS filesystem
@cindex Filesystems
This option controls support for mounting MS-DOS disks and disk
partitions under FreeBSD.  The @samp{pcfs} manual page is presently very
bogus.

@item pseudo-device ppp @var{number}
@findex ppp
@cindex Point-To-Point Protocol
@cindex Network interfaces
The @samp{ppp} pseudo-device provides support for the Internet
Point-to-Point protocol (RFC 1351 @i{et seq}), implemented as a line
discipline over standard serial links.  @var{number} should be the
number of simultaneous PPP interfaces which will be configured.

@item pseudo-device pty @var{number}
@findex pty
@cindex Pseudo-terminals
This pseudo-device provides support for pseudo-ttys, which are required
for @samp{rlogin}, @samp{telnet}, and @samp{xterm} to operate correctly;
@var{number} should be set to the total number of these programs you
expect to have running at any given time.  Because pty's are not as yet
dynamically allocated, and the underlying structures are large, it is
best to keep this value as small as feasible, until this deficiency is
remedied.

@item options QUOTA
@findex QUOTA
@cindex Disk quotas
@cindex Filesystems
The @samp{QUOTA} option enables support for disk quotas.  Note that NFS
quota support is not available.

@item pseudo-device sl @var{number}
@findex sl
@cindex Serial Line Internet Protocol
@cindex SLIP
@cindex CSLIP
@cindex IP
@cindex Network interfaces
This pseudo-device provides support for the Serial Line Internet
Protocol (RFC 1055), implemented as a line discipline over standard
serial links.  It includes support for Van Jacobson header compression.
@var{number} should be the number of simultaneous SLIP interfaces which
will be configured.  See also the @samp{slattach} manual page.

@item options SYSVSHM
@item options SYSVSEM
@item options SYSVMSG
@itemx options SHMMAXPGS=@var{value}
@findex SYSVSHM
@findex SYSVSEM
@findex SYSVMSG
@findex SHMMAXPGS
@cindex System V shared memory
@cindex System V semaphores
@cindex System V message queues
@cindex System V IPC
@cindex Shared memory, System V
@cindex Semaphores, System V
@cindex Message queues, System V
@cindex IPC, System V
The @samp{SYSVSHM} option enables kernel-side emulation of System
V-compatible shared memory.  The @samp{SHMMAXPGS} option (default 64
pages or 256K) determines the maximum amount of shared memory available
under this mechanism.  The @samp{SYSVSEM} option provides emulation of
System V-compatible semaphores, and likewise @samp{SYSVMSG} for message
queues.

@item options RMP
@findex RMP
@cindex Remote maintenance protocol
@cindex Networking domains
This option should control the inclusion of support for HP's remote
maintenance protocol, but the source code is not included in FreeBSD at
present, so enabling it will not result in any good.

@item pseudo-device tb
@findex tb
@cindex Tablet line discipline
The @samp{tb} pseudo-device provides support for the `tablet' line
discipline.  Nobody on the FreeBSD team actually has one of the tablets
in question, so we have no idea if this actually works or not.  It may
not even compile.

@item options "TCP_COMPAT_42"
@findex TCP_COMPAT_42
@cindex 4.2 Compatibility
@cindex Compatibility options
@cindex TCP
This option controls the perpetuation of several bugs inherited from the
4.2BSD implementation of TCP.  It should only be defined in the
circumstances outlined for @samp{COMPAT_42}, above.

@item pseudo-device tun
@findex tun
@cindex Network interfaces
The @samp{tun} driver provides a network interface which is attached to
a character device.  In this way, a user-mode program can grab packets
out of the networking system, fiddle with them or move them around, and
pass stuff packets back up into the kernel.  It is not known if this
device either compiles or operates correctly, although it was believed
to do both at some time in the past.

@item options UCONSOLE
@findex UCONSOLE
@cindex Console redirection
This option allows any old user to grab kernel output away from the
console and send it to the tty of their choice.  It presents an
incredile security hole for some systems, but is necessary in order to
allow programs like @samp{xconsole} to operate.  (The alternative,
making @samp{xconsole} set-uid root, opens the exact same security
hole.)

@item options XE
@findex XE
@cindex X.25
@cindex IEEE 802.2 LLC
@cindex Network interfaces
@cindex Ethernet
This option should control the inclusion of support for running X.25
over IEEE 802.2 LLC class 2, but that code was not included in the
Networking/2 release, so enabling it will disable kernel compilation.
Requires @samp{CCITT}.

@item options XSERVER
@findex XSERVER
@cindex X Window System
This obsolescent option enables support in the @samp{pc} console
driver for certain operations required by the XFree86 server.
@end table

@node Performance, Devices, Subsystems, Top
@c node,next,prev,up

@chapter Performace and Debugging Options

The following options are provided for system performace optimization.
Note that kernel profiling is supported via the @samp{-p} option to the
@samp{config} command; for more information see the @samp{config} manual
page.

@table @code
@item psuedo-device ddb
@findex ddb
@cindex Kernel debugger
@cindex Debugger, kernel
This option enables the @samp{ddb} debugger, taken from Mach.  See the
@samp{ddb} and @samp{dbsym} manual pages for more information on the use
of this debugger.

@item options DIAGNOSTIC
@itemx options NAMEI_DIAGNOSTIC
@itemx options PARANOID
@findex DIAGNOSTIC
@findex NAMEI_DIAGNOSTIC
@findex PARANOID
@cindex Debugging options
These debugging options reduce performace.  They are intended to enable
certain internal consistency checks which are not supposed to fail
during correct operation, and so are normally disabled for performace
reasons.

@item options FASTLINKS
@findex FASTLINKS
@cindex Symbolic links
@cindex Filesystems
The @samp{FASTLINKS} option enables the creation of symbolic links whose
target names reside entirely within the i-node of the link, when
possible.  This results in faster access for those links which are short
enough (in practice, most of them).  All kernels can read such links,
but only @samp{FASTLINKS} kernels will create them, for compatibility
with older kernels lacking such support.

@item options ICMPPRINTFS
@findex ICMPPRINTFS
@cindex Debugging options
@cindex ICMP
This option is defined to allow debugging of ICMP (@dfn{Internet Control
Message Protocol}) packets in the kernel.  When defined and the
@samp{icmpprintfs} kernel variable (default false) is set to true, ICMP
packets will be printed out to the console when received.  Note that it
is probably better to use @samp{tcpdump} for this kind of debugging.

@item options KGDB
@findex KGDB
@cindex Kernel debugger
@cindex Debugger, kernel
@cindex Remote debugging
The @samp{KGDB} option enables certain bits of kernel code which will
eventually be able to talk to a remote copy of the @samp{gdb} debugger
over a serial connection.  The present code does not work, but users are
invited to hack on it and contribute the changes back to the FreeBSD
team.

@item options MCLSHIFT=@var{value}
@findex MCLSHIFT
@cindex Network parameters
This option controls the number of bytes in an mbuf cluster, which is
one of the basic units through which network data is managed.  It is
equal to the log base two of @samp{MCLBYTES}, the size of an mbuf
cluster, and defaults to eleven (for an @samp{MCLBYTES} of 2048).  It
will likely eventually be bumped up to twelve (4096), so that the
network code can take advantage of page flipping to reduce the numer of
copies necessary.

@item options SUBNETSARELOCAL
@findex SUBNETSARELOCAL
@cindex TCP
@cindex Network parameters
This option controls whether the TCP system believes that machines on
other subnets of your network are considered to be ``local'' to your
host.  For most systems, this option should be on (the default); if you
are directly connected to a class A network, however, then it may need
to be turned off.  (This is true of networks like the MILNET.)

@item options "SYMTAB_SPACE=@var{value}"
@findex SYMTAB_SPACE
@cindex Debugger, kernel
@cindex Kernel debugger
This obsolescent option controls the amount of space that will be
statically allocated in the debugger source code to hold the kernel
symbol table that @samp{dbsym} sticks there.  Eventually this will be
dynamically allocated at load time.  The default @var{value} is 63000
bytes.
@end table

@node Devices, Internals, Performance, Top

@chapter Device Options

There are different device selections available depending on the type of
bus present in your computer.  We will cover generic FreeBSD devices,
ISA-bus devices, and EISA-bus devices.  A separate section describes the
devices available in the SCSI subsystem.

@menu
* Generic::             Devices available in all FreeBSD systems.
* ISA::                 Devices specific to the ISA bus.
* EISA::                Devices specific to the EISA bus.
* MCA::                 No support for Micro Channel, yet.
* PCI::                 No support for PCI, yet.
* SCSI::                The SCSI subsystem.
@end menu

@node Generic, ISA,, Devices
@section Generic Devices and Options

The following devices and options are available in all FreeBSD
configurations.  In addition to these devices, a selection of ISA
devices (@pxref{ISA}) is required in order to generate a workable
system.

@table @code
@item machine "i386"
@findex i386
This mandatory declaration informs the @samp{config} program that you
are using an i386 or compatible CPU, and enables the selection of all
the other devices listed here.

@item cpu "I386_CPU"
@itemx cpu "I486_CPU"
@findex I386_CPU
@findex I486_CPU
These two options control which specific CPUs will be supported by the
generated kernel.  If the kernel detects that it is not running on a CPU
for which support was enabled, it will panic quickly upon startup.  If
you do not expect to need to run your kernel on an i386 or similar CPU,
leaving out that support can increase virtual memory system performance.

@item options "MATH_EMULATE"
@findex MATH_EMULATE
@cindex Floating-point emulator
@cindex i387
When this option is defined, the math coprocessor emulator is compiled
into the kernel.  When it is not defined and the coprocessor is absent,
programs which use floating-point operations are automatically killed.

@item device npx0 at isa? port "IO_NPX" irq 13 vector npxintr
@findex npx
@cindex i386
The @samp{npx} device provides support for the i387 numeric coprocessor
and the floating-point portions of the i486 CPU.  This will eventually
be fixed to not require ISA to be configured.

@item pseudo-device speaker
@findex speaker
The @samp{speaker} pseudo-device provides support for rudimentary access
to the PC's speaker via @file{/dev/spkr}.  It provides a
character-device interface which interprets @samp{PLAY} strings similar
to IBM PC Advanced BASIC, as well as an @samp{ioctl} interface with more
fine-grained control.  See the @samp{spkr} manual page for more
information.
@end table

@node ISA, EISA, Generic, Devices
@section ISA-bus Devices and Options

The following options are specific to ISA-bus devices and systems.
Since the EISA bus is backwards-compatible with the ISA bus, all these
options also apply to EISA systems.  The same goes for VESA Local Bus
(VL-Bus) systems.

@table @code
@item controller isa0
@findex isa
This @strong{mandatory} declaration must precede any other devices
listed in this section.  It provides the basic support for the ISA-bus
glue logic, including DMA and autoconfiguration.

@item controller aha0 at isa? port "IO_AHA0" bio irq 11 drq 5 vector ahaintr
@findex aha
@cindex Adaptec 154x
@cindex SCSI host adaptors
The @samp{aha} device supports the Adaptec 154x series of SCSI
controllers, and attempts to support other vendors' controllers which
claim compatibility with the Adaptec 1542, such as the BusLogic 545.
This device is included in the @samp{GENERICAH} distribution kernel.
The @samp{scbus} device (@pxref{SCSI}) is a prerequisite for this
device.

@item controller bt0 at isa? port "IO_BT0" bio irq 12 vector btintr
@findex bt
@cindex Bustek 742
@cindex SCSI host adaptors
This device supports the Bustek 742 SCSI controller.  It is included in
the @samp{GENERICBT} distribution kernel; the @samp{scbus} device
(@pxref{SCSI}) is a prerequisite.

@item options COM_BIDIR
@findex COM_BIDIR
@cindex Bi-directional serial ports
@cindex Serial ports
This option enables bi-directional support in the @samp{sio} serial
driver.  This option is slated for removal, at which time bi-directional
support will always be enabled.  See the @samp{comcontrol} manual page
for more information.

@item options COM_MULTIPORT
@findex COM_MULTIPORT
@cindex Multi-port serial boards
@cindex Serial ports
This option enables support in the @samp{sio} serial driver for certain
multi-port serial boards.

@item device ed0 at isa? port 0x280 net irq 5 iomem 0xd8000 vector edintr
@itemx device ed1 at isa? port 0x300 net irq 5 iomem 0xd8000 vector edintr
@findex ed
@cindex Western Digital 80x3
@cindex 3Com 3C503
@cindex Novel NE1000/NE2000
@cindex Network interfaces
@cindex Ethernet
The @samp{ed} network interface driver provides support for the Western
Digital/SMC 80x3 series, the 3Com 3c503, and Novell NE1000 and NE2000
series of Ethernet controllers.  It automatically detects differences
among the various versions of these controllers and adapts
appropriately.  The @samp{ed1} line shown is for the Novell boards; the
@samp{ed0} line is appropriate for all other supported controllers.
(The Novell controllers cannot be configured to use port 0x280.)

@item controller fdc0 at isa? port "IO_FD1" bio irq 6 drq 2 vector fdintr
@itemx disk fd0 at fdc0 drive 0
@itemx disk fd1 at fdc0 drive 1
@itemx tape ft0 at fdc0 drive 2
@findex fd
@findex ft
@cindex Floppy disk
@cindex Floppy tape
@cindex QIC-80
@cindex Tape drives
@cindex Cartridge tape drives
@cindex Quarter-Inch-Cartridge (QIC) tape drives
@cindex Disk drives
The @samp{fdc} driver provides support for the standard PC floppy-disk
controller.  The @samp{fd} sub-driver supports 3.5-- and 5.25-inch
floppy disks in the standard 360KB, 720KB, 1200KB, 1440KB, and 2880KB
formats, as well as a number of other formats not supported by DOS.  The
@samp{ft} driver is available for QIC-80 ``floppy tape'' support.
The drivers support formatting of both tapes and disks.  This driver is
substantially improved from that shipped in previous releases of
FreeBSD.

@item device ie0 at isa? port 0x360 net irq 7 iomem 0xd0000 vector ieintr
@findex ie
@cindex AT&T EN100
@cindex AT&T StarLAN 10
@cindex Network interfaces
@cindex Ethernet
@cindex StarLAN
This network interface driver provides support for the AT&T StarLAN 10
and EN100 family of controllers.  Note that the configuration specified
here is not the default configuration, but one which attempts to deal
with the conflicts that arise in more modern systems.  (It is expected
that this driver will be expanded in the future to support other similar
cards in the manner of @samp{ed}.)

@item device is0 at isa? port 0x280 net irq 10 drq 7 vector isintr
@findex is
@cindex Isolan 4141-0
@cindex Isolink 4110
@cindex Ethernet
@cindex Network interfaces
The @samp{is} network interface driver supports the Isolan 4141-0 and
Isolink 4110 Ethernet controllers.

@c @item device ix0 at isa? port 0x320 net irq 10 iomem 0xd0000 iosiz 32768 \
@c @itemx vector ixintr
@c @findex ix
@c @cindex Intel EtherEXPRESS
@c @cindex Ethernet
@c @cindex Network interfaces
@c This device is known to exist, but is not presently in the FreeBSD
@c source tree.  When it is made available, this information will be
@c updated.

@item device lpa0 at isa? port "IO_LPT1" tty
@itemx device lpt0 at isa? port "IO_LPT1" tty irq 7 vector lptintr
@findex lpa
@findex lpt
@cindex Parallel printers
The @samp{lpa} device provides support for the parallel printer driver
accessed as @file{/dev/lp}.  The @samp{lpt} driver provides the same
functionality, but only works with those printer controllers which
support interrupt-driven operations.  If you receive @samp{ISA strayintr
7} messages correlated with the use of the @samp{lpa} driver, chances
are that your controller supports interrupt-driven operation, and you
should switch to the @samp{lpt} driver.

The @samp{lpa} driver is obsolete, and will be removed in release 1.2,
to be replaced by special flags to the @samp{lpt} driver.

@item device mcd0 at isa? port 0x300 bio irq 10 vector mcdintr
@findex mcd
@cindex Mitsumi CD-ROM
@cindex CD-ROM
This device provides support for the Mitsumi non-SCSI CD-ROM drive.
Performance is known to be quite slow.

@c mse, anyone?

@item device pc0 at isa? port "IO_KBD" tty irq 1 vector pcrint
@itemx device sc0 at isa? port "IO_KBD" tty irq 1 vector scintr
@itemx options NCONS=@var{value}
@itemx options COMCONSOLE
@findex pc
@findex sc
@findex NCONS
@findex COMCONSOLE
@cindex Console devices
@cindex pccons
@cindex Syscons
@cindex Virtual consoles
@cindex X Window System
The @samp{pc} and @samp{sc} devices provide support for the system
display and keyboard, which is the default console.  There might
actually be documentation somewhere for both of these.  The @samp{sc}
device requires the @samp{NCONS} option to be defined to some value; it
represents the number of virtual consoles to be provided by the driver;
a reasonable value is 8.  One of @samp{pc} or @samp{sc} is presently
required unless @samp{COMSONSOLE} is enabled, in which case a serial
port is made into the console.

@c sb, anyone?

@item device sio0 at isa? port "IO_COM1" tty irq 4 vector siointr
@itemx device sio1 at isa? port "IO_COM2" tty irq 3 vector siointr
@itemx device sio2 at isa? port "IO_COM3" tty irq 5 vector siointr
@itemx device sio3 at isa? port "IO_COM4" tty irq 9 vector siointr
@findex sio
@cindex Serial ports
@cindex National 8250/16450/16550
@cindex Bi-directional serial ports
@cindex Multi-port serial boards
The @samp{sio} driver provides support for high-speed serial
communications using the standard 8250, 16450, and 16550 UART chips.  It
provides a standard tty interface for these devices as
@file{/dev/tty@var{unit}}, and, when enabled with the @samp{comcontrol}
program, a call-out capability as @file{/dev/cua@var{unit}} (@var{unit}
is two digits, zero-padded in both cases).  Certain multi-port systems
are also supported.

@item device uha0 at isa? port "IO_UHA0" bio irq 14 drq 5 vector uhaintr
@findex uha
@cindex Ultrastor 14F
@cindex Ultrastor 34F
@cindex SCSI host adaptors
This device supports the Ultrastor 14F and related SCSI controllers.  It
is included in the @samp{GENERICBT} distribution kernel, and requires
@samp{scbus} (@pxref{SCSI}) as a prerequisite.  The Ultrastor 24F is not
supported.

@item controller wdc0 at isa? port "IO_WD1" bio irq 14 vector wdintr
@itemx disk wd0 at wdc0 drive 0
@itemx disk wd1 at wdc0 drive 1
@findex wd
@cindex Western Digital WD100x
@cindex ST-506 hard disks
@cindex RLL hard disks
@cindex ESDI hard disks
@cindex IDE hard disks
@cindex Disk drives
The @samp{wd} device supports standard ST-506, RLL, ESDI, and IDE hard
disks, as controlled by the Western Digital WD100x series of controllers
(and compatible hardware).  This version is substantially improved from
that provided in FreeBSD 1.0.

@item device wt0 at isa? port 0x300 bio irq 5 drq 1 vector wtintr
@findex wt
@cindex Archive QIC-02
@cindex Wangtek QIC-02
@cindex Cartridge tape drives
@cindex QIC-02
@cindex QIC-36
@cindex Tape drives
@cindex Quarter-Inch-Cartridge (QIC) tape drives
This driver supports Archive QIC-02 and Wangtek QIC-02 and QIC-36
cartridge tape controllers.
@end table

@node EISA, MCA, ISA, Devices
@section EISA-bus Devices and Options

There is presently only one EISA-specific device driver.

@table @code
@item controller ahb0 at isa? bio irq 11 vector ahbintr
@findex ahb
@cindex Adaptec 174x
@cindex SCSI host adaptors
The @samp{ahb} driver provides support for the Adaptec AHA-174x series
of SCSI controllers.  This controller is included in the
@samp{GENERICAH} distribution kernel, and requires the @samp{scbus}
driver (@pxref{SCSI}) as a prerequisite.
@end table

@node MCA, PCI, EISA, Devices
@section Micro Channel Devices and Options

@cindex Micro Channel Architecture
We don't support Micro Channel right now.  Anyone interested in working
on Micro Channel support should send mail to
@samp{FreeBSD-Questions@@freefall.cdrom.com} for information on how to
help.

@node PCI, SCSI, MCA, Devices
@section PCI Devices and Options

@cindex PCI
We don't support PCI, either.  Anyone interested in working on PCI
support should send mail to @samp{FreeBSD-Questions@@freefall.cdrom.com}
for information on how to help.

@node SCSI,, PCI, Devices
@section The SCSI Subsystem

The SCSI subsystem consists of a set of adaptor-specific driver
routines, which were described in the previous sections, and the generic
SCSI device drivers, which handle the standardized interactions with
devices on the SCSI bus.

@c devices: cd, ch, scbus, sd, sg, st

@table @code
@item device cd0 
@findex cd
@cindex CD-ROM
@cindex SCSI devices
The @samp{cd} device provides support for CD-ROM drives.  Only one
@samp{cd} device need be configured, as the driver automatically
allocates units for each CD-ROM drive found.  Playing of audio CDs is
also supported, on drives which support it, through @code{ioctl} calls.
Support for retrieval of CD audio over the SCSI bus is not presently
available.

@item device ch0
@findex ch
@cindex Media changers
@cindex SCSI devices
The @samp{ch} driver supports SCSI media changers; this may include
tape, removable disk, and CD changers.  One @samp{ch} device should be
configured for each changer you expect to support.

@item device scbus0
@findex scbus
@cindex SCSI bus management
This driver forms the core of the SCSI subsystem.  It provides the
device-independent routines that manage SCSI transactions, keep track of
attached devices, and act as glue between SCSI-device-specific drivers
and system-specific host adaptors.  This device is @emph{mandatory} for
all SCSI systems.

@item device sd0
@findex sd
@cindex SCSI devices
@cindex Disk drives
The @samp{sd} driver provides access to non-removable SCSI disks.  One
@samp{sd} device should be defined for each disk you expect to have
simultaneously connected to the system.

@c @item device sg0
@c @findex sg
@c @cindex SCSI devices
@c @cindex Generic SCSI
@c @cindex Unsupported SCSI devices
@c This driver provides support for development of user-mode drivers and
@c other programs which access the SCSI bus directly.  One @samp{sg} device
@c should be defined for each @emph{host adaptor} you have installed in
@c your system.

@item device st0
@findex st
@cindex SCSI devices
@cindex Tape drives
@cindex Quarter-Inch-Cartridge (QIC) tape drives
The @samp{st} driver supports generic SCSI tape drives.  One @samp{st}
device should be defined for each tape drive you wish to access.  See
the @samp{st} manual page for information about how to manipulate the
parameters of this device.

@item device uk0
@findex uk
@cindex SCSI devices
@cindex Unknown SCSI devices
The @samp{uk} driver provides an attachment point for all otherwise
unrecognized SCSI devices.  You can't actually do anything with such a
device, except perhaps send it an inquiry command using the @samp{scsi}
program (q.v.).
@end table

@node Internals, Index, Devices, Top

@chapter Internal Use Only

Eventually, this chapter will document some of the kernel manifest
constants which are not defines, but which can be tweaked in various
header files.

@node Index,, Internals, Top
@appendix General Index

Items in @code{typewriter} font are option or device names.

@printindex cp

@bye