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diff --git a/sys/doc/options.doc b/sys/doc/options.doc new file mode 100644 index 000000000000..178eaf0b3c59 --- /dev/null +++ b/sys/doc/options.doc @@ -0,0 +1,682 @@ +$Id: options.doc,v 1.10 1994/06/28 14:00:21 jkh Exp $ + + This file documents the configuration options available in the +FreeBSD operating system. + + Copyright (C) 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. + +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. + +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. + +`pseudo-device bpfilter NUMBER' + The `bpfilter' pseudo-device is the Berkeley Packet Filter, + developed by Lawrence Berkeley Labs and based on an earlier packet + filter from Stanford. See the `bpf' manual page for more details. + The NUMBER given is the maximum number of simultaneous users + permitted. (NB: in previous version of BPF, the NUMBER had to be + greater than the number of interfaces; this space is now + dynamically allocated so this requirement is no longer present.) + +`options CCITT' + The `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. + +`options "COMPAT_42"' + 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 + release of FreeBSD. + +`options "COMPAT_43"' + 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. + +`options "COMPAT_102"' + 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 backwards compatiblity. + +`options "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 `132.198.3' and `132.198.4', + and the `132.198.3' side receives a packet addressed to + `132.198.4.255', it will forward the packet as a broadcast on that + subnet. + + This option will likely be replaced by run-time configuration in a + future release of FreeBSD. + +`options "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 an diskimage. + +`pseudo-device ether' + 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 `ed', `ie', and `is'. This code is + due for a redesign. + +`options EON' +`pseudo-device eon' + The `eon' network interface supports the ISO 8473 + Connectionless-Mode Network Protocol, tunnelled through IP version + 4. `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. + +`options FIFO' + This option enables support for System V- and POSIX-style named + pipes or fifos. + +`options GATEWAY' +`options IPFORWARDING=VALUE' +`options IPSENDREDIRECTS=VALUE' + 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 `GATEWAY' option turns + on `IPFORWARDING', and also controls the sizing of certain system + tables. The `IPFORWARDING' option controls the initial value of + the `ipforwarding' kernel variable (default 1 if `GATEWAY' + defined, 0 otherwise), which controls whether packets are acutally + forwarded or not; VALUE should be either `0' or `1'. + `IPSENDREDIRECTS' controls the initial value of the + `ipsendredirects' variable (default is one, but should be changed + to zero); its VALUE should also be either `0' or `1'. + + This option will be replaced by run-time configuration in a future + release of FreeBSD. + +`options INET' + 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. + +`options ISO' +`options TPIP' + 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 + `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). + + This option will likely be removed in a future release of FreeBSD. + +`options ISOFS' + The `ISOFS' option enables kernel support for the ISO 9660 CD-ROM + filesystem, including RockRidge extensions. + +`options "ISO_X25ESIS"' + This option controls whether ISO 9542 ESIS is run over ITU-T X.25 + link layers. This requires the `CCITT' option to be enabled as + well. + + This option will likely be removed in a future release of FreeBSD. + +`options KTRACE' + This option enables the tracing of several classes of internal + kernel events. See the `ktrace' command for more details. + Recommended. + +`pseudo-device log' + The `log' pseudo-device provides kernel support to send kernel + messages to `syslog'. It is mandatory. + +`pseudo-device loop' + The `loop' pseudo-device provides the trivial network interface. + It is required when any networking options are enabled. + +`options MACHVMCOMPAT' + This option enables a Mach-compatible interface to the virtual + memory subsystem, supporting system calls `vm_allocate', + `vm_deallocate', `vm_inherit', and `vm_protect'. (Given the + nature of the VM system, it is impossible to support a Mach-style + `vm_region' call, and in every case the `map' argument is ignored + and replaced with the calling process's own map.) + +`options MFS' + This option enables support for the memory filesystem, an in-core + filesystem which lives in the swap area. Using MFS as a `/tmp' + filesystem can dramatically increase the speed of + temporary-space-intensive operations such as compilations. See the + `mount_mfs' manual page for more details. + +`options MULTICAST' + Enable multicast support for things like vat, nv, etc. + +`options MROUTING' + Enable multicast routing support (generally goes hand-in-hand with + the above). See also mrouted(1). + +`options NFS' + The `NFS' option enables support for Sun's Network File System. + (Also called "Nightmare" or "Not a"....) 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 `mount' manual page + for more details. + +`options NS' +`options NSIP' + `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 `NSIP' + option enables encapsulation of XNS IDP over IP. + + These options will likely be removed in a future release of + FreeBSD. + +`options "PANIC_REBOOT_WAIT_TIME=TIME"' + This option controls how long the system waits after a panic + before it reboots. If a TIME of zero is specified, it reboots + immediately; otherwise, 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. + +`options PCFS' + This option controls support for mounting MS-DOS disks and disk + partitions under FreeBSD. The `pcfs' manual page is presently very + bogus. + +`pseudo-device ppp NUMBER' + The `ppp' pseudo-device provides support for the Internet + Point-to-Point protocol (RFC 1351 et seq), implemented as a line + discipline over standard serial links. NUMBER should be the + number of simultaneous PPP interfaces which will be configured. + +`pseudo-device pty NUMBER' + This pseudo-device provides support for pseudo-ttys, which are + required for `rlogin', `telnet', and `xterm' to operate correctly; + 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. + +`options QUOTA' + The `QUOTA' option enables support for disk quotas. Note that NFS + quota support is not available. + +`pseudo-device sl NUMBER' + 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. NUMBER should be the number of simultaneous SLIP + interfaces which will be configured. See also the `slattach' + manual page. + +`options SYSVSHM' +`options SYSVSEM' +`options SYSVMSG' +`options SHMMAXPGS=VALUE' + The `SYSVSHM' option enables kernel-side emulation of System + V-compatible shared memory. The `SHMMAXPGS' option (default 64 + pages or 256K) determines the maximum amount of shared memory + available under this mechanism. The `SYSVSEM' option provides + emulation of System V-compatible semaphores, and likewise + `SYSVMSG' for message queues. + +`options "TCP_COMPAT_42"' + 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 `COMPAT_42', above. + + This option will likely be replaced by run-time configuration in a + future release of FreeBSD. + +`pseudo-device tun' + The `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. + +`options UCONSOLE' + 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 `xconsole' to operate. + +`options XSERVER' + This obsolescent option enables support in the `pc' console driver + for certain operations required by the XFree86 server. + +Performace and Debugging Options +******************************** + + The following options are provided for system performace +optimization. Note that kernel profiling is supported via the `-p' +option to the `config' command; for more information see the `config' +manual page. + +`psuedo-device ddb' + This option enables the `ddb' debugger, taken from Mach. See the + `ddb' and `dbsym' manual pages for more information on the use of + this debugger. + +`options DIAGNOSTIC' +`options NAMEI_DIAGNOSTIC' +`options PARANOID' + 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. + +`options FASTLINKS' + The `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 `FASTLINKS' kernels will create them, for + compatibility with older kernels lacking such support. + +`options ICMPPRINTFS' + This option is defined to allow debugging of ICMP ("Internet + Control Message Protocol") packets in the kernel. When defined + and the `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 `tcpdump' for + this kind of debugging. + +`options KGDB' + The `KGDB' option enables certain bits of kernel code which will + eventually be able to talk to a remote copy of the `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. + +`options MAXMEM=SIZE' + The `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. + +`options SUBNETSARELOCAL' + 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.) + +`options "SYMTAB_SPACE=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 `dbsym' sticks there. Eventually this will be + dynamically allocated at load time. The default VALUE is 63000 + bytes. + +`options "UPDATE_INTERVAL=VALUE"' + This option controls the wait time between successive `sync' + operations run by the `update' system process (pid 3). This option + will be replaced by run-time configuration in a future release of + FreeBSD. + +`options DUMMY_NOPS' + This option controls the use of real Nops for bus operations. + This might break on older systems so should be used with care. + +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. + +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 (*note ISA::.) is required in order to generate a workable +system. + +`machine "i386"' + This mandatory declaration informs the `config' program that you + are using an i386 or compatible CPU, and enables the selection of + all the other devices listed here. + +`cpu "I386_CPU"' +`cpu "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. + +`options "MATH_EMULATE"' + 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. + +`device npx0 at isa? port "IO_NPX" irq 13 vector npxintr' + The `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. + +`pseudo-device speaker' + The `speaker' pseudo-device provides support for rudimentary access + to the PC's speaker via `/dev/spkr'. It provides a + character-device interface which interprets `PLAY' strings similar + to IBM PC Advanced BASIC, as well as an `ioctl' interface with more + fine-grained control. See the `spkr' manual page for more + information. + +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. + +`controller isa0' + This *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. + +`controller aha0 at isa? port "IO_AHA0" bio irq 11 drq 5 vector ahaintr' +`options "TUNE_1542"' + The `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 `GENERICAH' + distribution kernel. The `scbus' device (*note SCSI::.) is a + prerequisite for this device. + + 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 `TUNE_1542' option to enable + bus-timing detection. + +`controller bt0 at isa? port "IO_BT0" bio irq 12 vector btintr' + This device supports the Bustek 742 SCSI controller. It is + included in the `GENERICBT' distribution kernel; the `scbus' device + (*note SCSI::.) is a prerequisite. + +`options ALLOW_CONFLICT_IOADDR' + 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 your driver. + +`options ALLOW_CONFLICT_IRQ' + 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! + +`options COM_MULTIPORT' + This option enables support in the `sio' serial driver for certain + multi-port serial boards. + +`device ed0 at isa? port 0x280 net irq 5 iomem 0xd8000 vector edintr' +`device ed1 at isa? port 0x300 net irq 5 iomem 0xd8000 vector edintr' + The `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 `ed1' line shown is for the Novell + boards; the `ed0' line is appropriate for all other supported + controllers. (The Novell controllers cannot be configured to use + port 0x280.) + +`controller fdc0 at isa? port "IO_FD1" bio irq 6 drq 2 vector fdintr' +`disk fd0 at fdc0 drive 0' +`disk fd1 at fdc0 drive 1' +`tape ft0 at fdc0 drive 2' + The `fdc' driver provides support for the standard PC floppy-disk + controller. The `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 `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. + +`device ie0 at isa? port 0x360 net irq 7 iomem 0xd0000 vector ieintr' + 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 + `ed'.) + +`device is0 at isa? port 0x280 net irq 10 drq 7 vector isintr' + The `is' network interface driver supports the Isolan 4141-0 and + Isolink 4110 Ethernet controllers. + +`device lpt0 at isa? port "IO_LPT1" tty' +`device lpt0 at isa? port "IO_LPT1" tty irq 7 vector lptintr' +`device lpt0 at isa? port ? tty irq 7 vector lptintr' +`device lpt0 at isa? port ? tty' + The `lpt' driver provides support for the parallel printer driver + accessed as `/dev/lptN' (N=0, 1, ...). The current version of + this driver provides support for either polled or interrupt-driven + ports, a unification of the `lpt' and `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 `lpt', chances are that your controller + supports interrupt-driven operation, and you should switch to that + mode. + +`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. + +`device pc0 at isa? port "IO_KBD" tty irq 1 vector pcrint' +`device sc0 at isa? port "IO_KBD" tty irq 1 vector scintr' +`options NCONS=VALUE' +`options COMCONSOLE' + The `pc' and `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 `sc' device + requires the `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 `pc' or `sc' is presently + required unless `COMCONSOLE' is enabled, in which case a serial + port is made into the console. + +`device psm0 at isa? port "IO_KBD" tty irq 12 vector psmintr' + This driver provides support for the IBM-style PS/2 mouse now + popular on many PCs. This driver shares an address with the + console driver and therefore requires that the option + `ALLOW_CONFLICT_IOADDR' also be set. It is also important that + the console driver (`pc' or `sc') *preceed* this driver in your + kernel configuration file in order to get priority. All in all, + this driver is a hack and should really be integrated into the + console driver itself, evidence of which can be easily seen when + trying to use the mouse and keyboard at the same time in X (try + it). Volunteers willing to clean this up and do it properly are + most welcome! + +`device sio0 at isa? port "IO_COM1" tty irq 4 vector siointr' +`device sio1 at isa? port "IO_COM2" tty irq 3 vector siointr' +`device sio2 at isa? port "IO_COM3" tty irq 5 vector siointr' +`device sio3 at isa? port "IO_COM4" tty irq 9 vector siointr' + The `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 + `/dev/ttyUNIT', and, when enabled with the `comcontrol' program, a + call-out capability as `/dev/cuaUNIT' (UNIT is two digits, + zero-padded in both cases). Certain multi-port systems are also + supported. + +`device uha0 at isa? port "IO_UHA0" bio irq 14 drq 5 vector uhaintr' + This device supports the Ultrastor 14F and related SCSI + controllers. It is included in the `GENERICBT' distribution + kernel, and requires `scbus' (*note SCSI::.) as a prerequisite. + The Ultrastor 24F is not supported. + +`controller wdc0 at isa? port "IO_WD1" bio irq 14 vector wdintr' +`disk wd0 at wdc0 drive 0' +`disk wd1 at wdc0 drive 1' + The `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. + +`device wt0 at isa? port 0x300 bio irq 5 drq 1 vector wtintr' + This driver supports Archive QIC-02 and Wangtek QIC-02 and QIC-36 + cartridge tape controllers. + +`device ze0 at isa? port 0x300 net irq 5 iomem 0xd8000 vector zeintr' + 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. + +EISA-bus Devices and Options +============================ + + There is presently only one EISA-specific device driver. + +`controller ahb0 at isa? bio irq 11 vector ahbintr' + The `ahb' driver provides support for the Adaptec AHA-174x series + of SCSI controllers. This controller is included in the + `GENERICAH' distribution kernel, and requires the `scbus' driver + (*note SCSI::.) as a prerequisite. + +Micro Channel Devices and Options +================================= + + We don't support Micro Channel right now. Anyone interested in +working on Micro Channel support should send mail to +`FreeBSD-Questions@freefall.cdrom.com' for information on how to help. + +PCI Devices and Options +======================= + + We don't support PCI, either. Anyone interested in working on PCI +support should send mail to `FreeBSD-Questions@freefall.cdrom.com' for +information on how to help. + +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. + +`device cd0' + The `cd' device provides support for CD-ROM drives. Only one `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 `ioctl' calls. + Support for retrieval of CD audio over the SCSI bus is not + presently available. + +`device ch0' + The `ch' driver supports SCSI media changers; this may include + tape, removable disk, and CD changers. One `ch' device should be + configured for each changer you expect to support. + +`device scbus0' + 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 *mandatory* for all SCSI systems. + +`device sd0' + The `sd' driver provides access to non-removable SCSI disks. One + `sd' device should be defined for each disk you expect to have + simultaneously connected to the system. + +`device st0' + The `st' driver supports generic SCSI tape drives. One `st' + device should be defined for each tape drive you wish to access. + See the `st' manual page for information about how to manipulate + the parameters of this device. + +`device uk0' + The `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 + `scsi' program (q.v.). + +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. + |