\input texinfo @c -*- texinfo -*-
@c -----------------------------------------------------------------------
@c Thus spoke the elders in days long gone by:
@c How to edit: use an existing entry as template, keep the file sorted
@c using the most keyword-ish thing. When done, make sure /usr/gnu/bin
@c is in your path, run "make" and THEN "cvs commit".
@c -----------------------------------------------------------------------
@setfilename options.info
@settitle Configuration Options for FreeBSD
@c @setchapternewpage odd
@c function index is option/pseudo/device names; concept is everything
$Id: options.texi,v 1.9 1994/06/08 23:42:06 phk Exp $
This file documents the configuration options available in the FreeBSD
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
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
Trademarks are property of their respective owners.
@title Configuration Options in FreeBSD
@subtitle for FreeBSD 1.1.5
@author Garrett A. Wollman
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
Redistributions of source code must retain the above copyright
notice and this list of conditions.
Redistributions in printed form must reproduce the above copyright
notice, this list of conditions and the preceding notice of
@node Top, Subsystems, (dir), (dir)
@top FreeBSD Configuration Options
This document describes kernel configuration options relevant to the
FreeBSD operating system between versions 1.1 and 1.2. 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.
* Subsystems:: Controlling subsystems.
* Performance:: Performance enhancement.
* Devices:: Device-control options.
* Internals:: Non-user-serviceable parts.
@node Subsystems, Performance, Top, Top
@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.
@item pseudo-device bpfilter @var{number}
@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.)
@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.
This option will likely be removed in a future release of FreeBSD.
@item options "COMPAT_42"
@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.
This option will be replaced by run-time configuration in a future
@item options "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 "COMPAT_102"
@cindex FreeBSD 1.0.2 compatibility
@cindex 1.0.2 Compatibility
@cindex Compatibility options
This option, which is not yet implemented, will control whether certain
entry points which were system calls in FreeBSD 1.0.2 but have been
replaced with library routines, are supported in the kernel for
@item options "DIRECTED_BROADCAST"
@findex DIRECTED_BROADCAST
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
This option will likely be replaced by run-time configuration in a
future release of FreeBSD.
@item options "DISKLABEL_UNPROTECTED"
@findex DISKLABEL_UNPROTECTED
This options disables the checks which normally protects the disklabel from
being overwritten. This allows dd of=/dev/rwd0d if=file bs=8k to restore
@item pseudo-device ether
@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.
@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.
This option will likely be removed in a future release of FreeBSD.
This option enables support for System V-- and POSIX-style named pipes
@itemx options IPFORWARDING=@var{value}
@itemx options IPSENDREDIRECTS=@var{value}
@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}.
This option will be replaced by run-time configuration in a future
@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.
@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
This option will likely be removed in a future release of FreeBSD.
@cindex ISO 9660 filesystem
@cindex Rock Ridge filesystem
The @samp{ISOFS} option enables kernel support for the ISO 9660 CD-ROM
filesystem, including RockRidge extensions.
@item options "ISO_X25ESIS"
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.
This option will likely be removed in a future release of FreeBSD.
This option enables the tracing of several classes of internal kernel
events. See the @samp{ktrace} command for more details. Recommended.
@cindex Kernel message logging
The @samp{log} pseudo-device provides kernel support to send kernel
messages to @samp{syslog}. It is mandatory.
@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
@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.)
@cindex Memory filesystem
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.
Enable multicast support for things like vat, nv, etc.
@cindex Multicast Routing
Enable multicast routing support (generally goes hand-in-hand with the
above). See also mrouted(1).
@cindex Network File System
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.
@cindex Xerox Network System
@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.
These options will likely be removed in a future release of FreeBSD.
@item options "PANIC_REBOOT_WAIT_TIME=@var{time}"
@findex PANIC_REBOOT_WAIT_TIME
This option controls how long the system waits after a panic before it
reboots. If a @var{time} of zero is specified, it reboots immediately;
otherwise, @var{time} is the number of seconds to wait before rebooting.
If, during the waiting period, a key is hit on the console, the
countdown stops and the system will wait for the user to copy down the
panic message and hit another key before rebooting.
@cindex MS-DOS filesystem
This option controls support for mounting MS-DOS disks and disk
partitions under FreeBSD. The @samp{pcfs} manual page is presently very
@item pseudo-device ppp @var{number}
@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}
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
The @samp{QUOTA} option enables support for disk quotas. Note that NFS
quota support is not available.
@item pseudo-device sl @var{number}
@cindex Serial Line Internet Protocol
@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.
@itemx options SHMMAXPGS=@var{value}
@cindex System V shared memory
@cindex System V semaphores
@cindex System V message queues
@cindex Shared memory, System V
@cindex Semaphores, System V
@cindex Message queues, 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
@item options "TCP_COMPAT_42"
@cindex 4.2 Compatibility
@cindex Compatibility options
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.
This option will likely be replaced by run-time configuration in a
future release of FreeBSD.
@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.
@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.
This obsolescent option enables support in the @samp{pc} console
driver for certain operations required by the XFree86 server.
@node Performance, Devices, Subsystems, Top
@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
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
@itemx options NAMEI_DIAGNOSTIC
@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
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
@cindex Debugging options
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.
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
@item options MAXMEM=@var{size}
The @samp{MAXMEM} option controls how much memory the kernel will
recognize on bootup, specified in kilobytes. This may be useful for
dealing with certain broken attachment busses (or the adapters thereon)
which are unable to deal with memory beyond a certain address.
@item options SUBNETSARELOCAL
@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}"
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
@item options "UPDATE_INTERVAL=@var{value}"
This option controls the wait time between successive @samp{sync}
operations run by the @samp{update} system process (pid 3). This option
will be replaced by run-time configuration in a future release of
@cindex Fast i/o bus operations
This option controls the use of real Nops for bus operations.
This might break on older systems so should be used with care.
@node Devices, Internals, Performance, Top
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.
* 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.
@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
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.
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"
@cindex Floating-point emulator
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
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
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
@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
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
@item options "TUNE_1542"
@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
Some older versions of this code would attempt to set the controller's
bus access speed to the fastest possible without losing data; we have
found that this makes the driver unusable for some users. If you wish
to enable this optimization, or if you suspect that your SCSI transfers
are running slower than they should, then you can use the @samp{TUNE_1542}
option to enable bus-timing detection.
@item controller bt0 at isa? port "IO_BT0" bio irq 12 vector btintr
@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 ALLOW_CONFLICT_IOADDR
@findex ALLOW_CONFLICT_IOADDR
@cindex Allow IO Address Conflict
@cindex ISA device management
Allow devices on the ISA bus to share conflicting IO address spaces.
This is generally an error, though things like PS/2 mouse drivers which
are implemented seperately from the keyboard driver will require this
option to be set. Note that this is almost always sub-optimal, and the
current PS/2 mouse driver will, in fact, frequently fight with the
keyboard if you try to use them concurrently. Needing this option
enabled is a sure sign that you need to consider a different design for
@item options ALLOW_CONFLICT_IRQ
@findex ALLOW_CONFLICT_IRQ
@cindex Allow IRQ Conflict
@cindex ISA device management
Allow devices on the ISA bus to share conflicting IRQ's. This is often
necessary for multiport serial cards which have several devices at the
same IRQ. Enable this only with caution!
@item options COM_MULTIPORT
@cindex Multi-port serial boards
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
@cindex Western Digital 80x3
@cindex Novel NE1000/NE2000
@cindex Network interfaces
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
@cindex Cartridge tape drives
@cindex Quarter-Inch-Cartridge (QIC) tape 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
@item device ie0 at isa? port 0x360 net irq 7 iomem 0xd0000 vector ieintr
@cindex Network interfaces
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
@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 @cindex Intel EtherEXPRESS
@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
@item device lpt0 at isa? port "IO_LPT1" tty
@itemx device lpt0 at isa? port "IO_LPT1" tty irq 7 vector lptintr
@itemx device lpt0 at isa? port ? tty irq 7 vector lptintr
@itemx device lpt0 at isa? port ? tty
@cindex Parallel printers
The @samp{lpt} driver provides support for the parallel printer driver
accessed as @file{/dev/lpt@var{N}} (@var{N}=0, 1, @dots{}). The current
version of this driver provides support for either polled or
interrupt-driven ports, a unification of the @samp{lpt} and @samp{lpa}
drivers from FreeBSD 1.1.
The first and second examples show explicit selection of a port address.
If the port is not specified, as in the third and fourth examples, the
driver defaults to whatever address the BIOS printer driver would have
used. The second and third examples select interrupt-driven I/O; if
polled mode is specified, as in the first and fourth examples, it is
impossible to enable interrupt-driven access at run time.
If you receive ``ISA strayintr 7'' messages correlated with the use of
the polled mode of @samp{lpt}, chances are that your controller supports
interrupt-driven operation, and you should switch to that mode.
@item device mcd0 at isa? port 0x300 bio irq 10 vector mcdintr
This device provides support for the Mitsumi non-SCSI CD-ROM drive.
Performance is known to be quite slow.
@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
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{COMCONSOLE} is enabled, in which case a serial
port is made into the console.
@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
@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
@item device uha0 at isa? port "IO_UHA0" bio irq 14 drq 5 vector uhaintr
@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
@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
@cindex Western Digital WD100x
@cindex ST-506 hard disks
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
@cindex Cartridge 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.
@item device ze0 at isa? port 0x300 net irq 5 iomem 0xd8000 vector zeintr
@cindex Network Interfaces
@cindex PCMCIA Ethernet Cards
This driver supports certain PCMCIA ethernet cards. It was originally
written for the IBM Credit Card Adapter and has also been tested
with the National Semi `InfoMover' PCMCIA card.
@node EISA, MCA, ISA, Devices
@section EISA-bus Devices and Options
There is presently only one EISA-specific device driver.
@item controller ahb0 at isa? bio irq 11 vector ahbintr
@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.
@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
@node PCI, SCSI, MCA, Devices
@section PCI Devices and Options
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
@c devices: cd, ch, scbus, sd, sg, st
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
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.
@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
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 @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
@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.
@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}
@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
@node Index,, Internals, Top
Items in @code{typewriter} font are option or device names.
projects / unix-history / blob