How to configure the Linux kernel/drivers/char

Howto configure the Linux kernel / drivers / char


 * Character device configuration
 * Character device configuration

Character devices

 * Option: VT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Virtual terminal if EMBEDDED
 * select INPUT
 * default y if !VIOCONS
 * If you say Y here, you will get support for terminal devices with display and keyboard devices. These are called "virtual" because you can run several virtual terminals (also called virtual consoles) on one physical terminal. This is rather useful, for example one virtual terminal can collect system messages and warnings, another one can be used for a text-mode user session, and a third could run an X session, all in parallel. Switching between virtual terminals is done with certain key combinations, usually Alt-.
 * The setterm command ("man setterm") can be used to change the properties (such as colors or beeping) of a virtual terminal. The man page console_codes(4) ("man console_codes") contains the special character sequences that can be used to change those properties directly. The fonts used on virtual terminals can be changed with the setfont ("man setfont") command and the key bindings are defined with the loadkeys ("man loadkeys") command.
 * You need at least one virtual terminal device in order to make use of your keyboard and monitor. Therefore, only people configuring an embedded system would want to say N here in order to save some memory; the only way to log into such a system is then via a serial or network connection.
 * If unsure, say Y, or else you won't be able to do much with your new shiny Linux system :-)


 * Option: VT_CONSOLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Support for console on virtual terminal if EMBEDDED
 * depends on VT
 * default y
 * The system console is the device which receives all kernel messages and warnings and which allows logins in single user mode. If you answer Y here, a virtual terminal (the device used to interact with a physical terminal) can be used as system console. This is the most common mode of operations, so you should say Y here unless you want the kernel messages be output only to a serial port (in which case you should say Y to "Console on serial port", below).
 * If you do say Y here, by default the currently visible virtual terminal (/dev/tty0) will be used as system console. You can change that with a kernel command line option such as "console=tty3" which would use the third virtual terminal as system console. (Try "man bootparam" or see the documentation of your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.)
 * If unsure, say Y.


 * Option: HW_CONSOLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on VT && !S390 && !UML
 * default y


 * Option: SERIAL_NONSTANDARD
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Non-standard serial port support
 * Say Y here if you have any non-standard serial boards—boards which aren't supported using the standard "dumb" serial driver. This includes intelligent serial boards such as Cyclades, Digiboards, etc. These are usually used for systems that need many serial ports because they serve many terminals or dial-in connections.
 * Note that the answer to this question won't directly affect the kernel: saying N will just cause the configurator to skip all the questions about non-standard serial boards.
 * Most people can say N here.


 * Option: COMPUTONE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Computone IntelliPort Plus serial support
 * depends on SERIAL_NONSTANDARD && BROKEN_ON_SMP
 * This driver supports the entire family of Intelliport II/Plus controllers with the exception of the MicroChannel controllers and products previous to the Intelliport II. These are multiport cards, which give you many serial ports. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server. If you have a card like that, say Y here and read .
 * To compile this driver as modules, choose M here: the modules will be called ip2 and ip2main.


 * Option: ROCKETPORT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Comtrol RocketPort support
 * depends on SERIAL_NONSTANDARD
 * This driver supports Comtrol RocketPort and RocketModem PCI boards.           These boards provide 2, 4, 8, 16, or 32 high-speed serial ports or         modems.  For information about the RocketPort/RocketModem  boards         and this driver read .
 * To compile this driver as a module, choose M here: the module will be called rocket.
 * If you want to compile this driver into the kernel, say Y here. If         you don't have a Comtrol RocketPort/RocketModem card installed, say N.


 * Option: CYCLADES
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Cyclades async mux support
 * depends on SERIAL_NONSTANDARD
 * This driver supports Cyclades Z and Y multiserial boards. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server.
 * For information about the Cyclades-Z card, read .
 * To compile this driver as a module, choose M here: the module will be called cyclades.
 * If you haven't heard about it, it's safe to say N.


 * Option: CYZ_INTR
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Cyclades-Z interrupt mode operation (EXPERIMENTAL)
 * depends on EXPERIMENTAL && CYCLADES
 * The Cyclades-Z family of multiport cards allows 2 (two) driver op modes: polling and interrupt. In polling mode, the driver will check the status of the Cyclades-Z ports every certain amount of time (which is called polling cycle and is configurable). In interrupt mode, it will use an interrupt line (IRQ) in order to check the status of the Cyclades-Z ports. The default op mode is polling. If unsure, say N.


 * Option: DIGIEPCA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Digiboard Intelligent Async Support
 * depends on SERIAL_NONSTANDARD
 * This is a driver for Digi International's Xx, Xeve, and Xem series of cards which provide multiple serial ports. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server. This driver supports the original PC (ISA) boards as well as PCI, and EISA. If you have a card like this, say Y here and read the file .
 * To compile this driver as a module, choose M here: the module will be called epca.


 * Option: ESPSERIAL
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Hayes ESP serial port support
 * depends on SERIAL_NONSTANDARD && ISA && BROKEN_ON_SMP && ISA_DMA_API
 * This is a driver which supports Hayes ESP serial ports. Both single port cards and multiport cards are supported.  Make sure to read .
 * To compile this driver as a module, choose M here: the module will be called esp.
 * If unsure, say N.


 * Option: MOXA_INTELLIO
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Moxa Intellio support
 * depends on SERIAL_NONSTANDARD && BROKEN_ON_SMP
 * Say Y here if you have a Moxa Intellio multiport serial card.
 * To compile this driver as a module, choose M here: the module will be called moxa.


 * Option: MOXA_SMARTIO
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Moxa SmartIO support
 * depends on SERIAL_NONSTANDARD
 * Say Y here if you have a Moxa SmartIO multiport serial card.
 * This driver can also be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called mxser. If you want to do that, say M here.


 * Option: ISI
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Multi-Tech multiport card support (EXPERIMENTAL)
 * depends on SERIAL_NONSTANDARD
 * This is a driver for the Multi-Tech cards which provide several serial ports. The driver is experimental and can currently only be built as a module. The module will be called isicom. If you want to do that, choose M here.


 * Option: SYNCLINK
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Microgate SyncLink card support
 * depends on SERIAL_NONSTANDARD && PCI && ISA_DMA_API
 * Provides support for the SyncLink ISA and PCI multiprotocol serial adapters. These adapters support asynchronous and HDLC bit synchronous communication up to 10Mbit/s (PCI adapter).
 * This driver can only be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called synclink. If you want to do that, say M here.


 * Option: SYNCLINKMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) SyncLink Multiport support
 * depends on SERIAL_NONSTANDARD
 * Enable support for the SyncLink Multiport (2 or 4 ports) serial adapter, running asynchronous and HDLC communications up to 2.048Mbit/s. Each ports is independently selectable for RS-232, V.35, RS-449, RS-530, and X.21
 * This driver may be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called synclinkmp. If you want to do that, say M here.


 * Option: N_HDLC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) HDLC line discipline support
 * depends on SERIAL_NONSTANDARD
 * Allows synchronous HDLC communications with tty device drivers that support synchronous HDLC such as the Microgate SyncLink adapter.
 * This driver can only be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called n_hdlc. If you want to do that, say M here.


 * Option: RISCOM8
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) SDL RISCom/8 card support
 * depends on SERIAL_NONSTANDARD && BROKEN_ON_SMP
 * This is a driver for the SDL Communications RISCom/8 multiport card, which gives you many serial ports. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server. If you have a card like that, say Y here and read the file .
 * Also it's possible to say M here and compile this driver as kernel loadable module; the module will be called riscom8.


 * Option: SPECIALIX
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Specialix IO8+ card support
 * depends on SERIAL_NONSTANDARD
 * This is a driver for the Specialix IO8+ multiport card (both the ISA and the PCI version) which gives you many serial ports. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server.
 * If you have a card like that, say Y here and read the file . Also it's possible to say M here and compile this driver as kernel loadable module which will be called specialix.


 * Option: SPECIALIX_RTSCTS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Specialix DTR/RTS pin is RTS
 * depends on SPECIALIX
 * The Specialix IO8+ card can only support either RTS or DTR. If you say N here, the driver will use the pin as "DTR" when the tty is in software handshake mode. If you say Y here or hardware handshake is on, it will always be RTS.  Read the file  for more information.


 * Option: SX
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Specialix SX (and SI) card support
 * depends on SERIAL_NONSTANDARD
 * This is a driver for the SX and SI multiport serial cards. Please read the file  for details.
 * This driver can only be built as a module ( = code which can be inserted in and removed from the running kernel whenever you want). The module will be called sx. If you want to do that, say M here.


 * Option: RIO
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Specialix RIO system support
 * depends on SERIAL_NONSTANDARD && BROKEN_ON_SMP
 * This is a driver for the Specialix RIO, a smart serial card which drives an outboard box that can support up to 128 ports. Product information is at . There are both ISA and PCI versions.


 * Option: RIO_OLDPCI
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Support really old RIO/PCI cards
 * depends on RIO
 * Older RIO PCI cards need some initialization-time configuration to determine the IRQ and some control addresses. If you have a RIO and this doesn't seem to work, try setting this to Y.


 * Option: STALDRV
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Stallion multiport serial support
 * depends on SERIAL_NONSTANDARD
 * Stallion cards give you many serial ports. You would need something like this to connect more than two modems to your Linux box, for instance in order to become a dial-in server.  If you say Y here, you will be asked for your specific card model in the next questions.  Make sure to read  in this case.  If you have never heard about all this, it's safe to say N.


 * Option: STALLION
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Stallion EasyIO or EC8/32 support
 * depends on STALDRV && BROKEN_ON_SMP
 * If you have an EasyIO or EasyConnection 8/32 multiport Stallion card, then this is for you; say Y. Make sure to read .
 * To compile this driver as a module, choose M here: the module will be called stallion.


 * Option: ISTALLION
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Stallion EC8/64, ONboard, Brumby support
 * depends on STALDRV && BROKEN_ON_SMP
 * If you have an EasyConnection 8/64, ONboard, Brumby or Stallion serial multiport card, say Y here. Make sure to read .
 * To compile this driver as a module, choose M here: the module will be called istallion.


 * Option: AU1000_UART
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Enable Au1000 UART Support
 * depends on SERIAL_NONSTANDARD && MIPS
 * If you have an Alchemy AU1000 processor (MIPS based) and you want to use serial ports, say Y. Otherwise, say N.


 * Option: AU1000_SERIAL_CONSOLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Enable Au1000 serial console
 * depends on AU1000_UART
 * If you have an Alchemy AU1000 processor (MIPS based) and you want to use a console on a serial port, say Y. Otherwise, say N.


 * Option: QTRONIX_KEYBOARD
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Enable Qtronix 990P Keyboard Support
 * depends on IT8712
 * Images of Qtronix keyboards are at .


 * Option: IT8172_CIR
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on QTRONIX_KEYBOARD
 * default y


 * Option: IT8172_SCR0
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Enable Smart Card Reader 0 Support 
 * depends on IT8712
 * Say Y here to support smart-card reader 0 (SCR0) on the Integrated Technology Express, Inc. ITE8172 SBC. Vendor page at ; picture of the board at .


 * Option: IT8172_SCR1
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Enable Smart Card Reader 1 Support 
 * depends on IT8712
 * Say Y here to support smart-card reader 1 (SCR1) on the Integrated Technology Express, Inc. ITE8172 SBC. Vendor page at <http://www.ite.com.tw/ia/brief_it8172bsp.htm>; picture of the board at <http://www.mvista.com/partners/semiconductor/ite.html>.


 * Option: A2232
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Commodore A2232 serial support (EXPERIMENTAL)
 * depends on EXPERIMENTAL && ZORRO && BROKEN_ON_SMP
 * This option supports the 2232 7-port serial card shipped with the Amiga 2000 and other Zorro-bus machines, dating from 1989. At a max of 19,200 bit/s, the ports are served by a 6551 ACIA UART chip each, plus a 8520 CIA, and a master 6502 CPU and buffer as well. The ports were connected with 8 pin DIN connectors on the card bracket, for which 8 pin to DB25 adapters were supplied. The card also had jumpers internally to toggle various pinning configurations.
 * This driver can be built as a module; but then "generic_serial" will also be built as a module. This has to be loaded before ser_a2232. If you want to do this, answer M here.


 * Option: SGI_SNSC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) SGI Altix system controller communication support
 * depends on (IA64_SGI_SN2 || IA64_GENERIC)
 * If you have an SGI Altix and you want to enable system controller communication from user space (you want this!), say Y. Otherwise, say N.


 * Option: SGI_TIOCX
 * Kernel Versions: 2.6.15.6 ...     bool SGI TIO CX driver support      depends on (IA64_SGI_SN2 || IA64_GENERIC)      help        If you have an SGI Altix and you have fpga devices attached        to your TIO, say Y here, otherwise say N.


 * Option: SGI_MBCS
 * Kernel Versions: 2.6.15.6 ...     tristate SGI FPGA Core Services driver support      depends on SGI_TIOCX      help        If you have an SGI Altix with an attached SABrick        say Y or M here, otherwise say N.


 * Option: Howto configure the Linux kernel/drivers/serial


 * Option: UNIX98_PTYS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Unix98 PTY support if EMBEDDED
 * default y
 * A pseudo terminal (PTY) is a software device consisting of two halves: a master and a slave. The slave device behaves identical to a physical terminal; the master device is used by a process to read data from and write data to the slave, thereby emulating a terminal. Typical programs for the master side are telnet servers and xterms.
 * Linux has traditionally used the BSD-like names /dev/ptyxx for masters and /dev/ttyxx for slaves of pseudo terminals. This scheme has a number of problems. The GNU C library glibc 2.1 and later, however, supports the Unix98 naming standard: in order to acquire a pseudo terminal, a process opens /dev/ptmx; the number of the pseudo terminal is then made available to the process and the pseudo terminal slave can be accessed as /dev/pts/ . What was traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
 * All modern Linux systems use the Unix98 ptys. Say Y unless you're on an embedded system and want to conserve memory.


 * Option: LEGACY_PTYS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Legacy (BSD) PTY support
 * default y
 * A pseudo terminal (PTY) is a software device consisting of two halves: a master and a slave. The slave device behaves identical to a physical terminal; the master device is used by a process to read data from and write data to the slave, thereby emulating a terminal. Typical programs for the master side are telnet servers and xterms.
 * Linux has traditionally used the BSD-like names /dev/ptyxx for masters and /dev/ttyxx for slaves of pseudo terminals. This scheme has a number of problems, including security. This option enables these legacy devices; on most systems, it is safe to say N.

"Maximum number of legacy PTY in use" 1 256
 * Option: LEGACY_PTY_COUNT
 * Kernel Versions: 2.6.15.6 ...
 * depends on LEGACY_PTYS
 * default "256"
 * The maximum number of legacy PTYs that can be used at any one time. The default is 256, and should be more than enough. Embedded systems may want to reduce this to save memory.
 * When not in use, each legacy PTY occupies 12 bytes on 32-bit architectures and 24 bytes on 64-bit architectures.


 * Option: PRINTER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Parallel printer support
 * depends on PARPORT
 * If you intend to attach a printer to the parallel port of your Linux box (as opposed to using a serial printer; if the connector at the printer has 9 or 25 holes ["female"], then it's serial), say Y. Also read the Printing-HOWTO, available from <http://www.tldp.org/docs.html#howto>.
 * It is possible to share one parallel port among several devices (e.g. printer and ZIP drive) and it is safe to compile the corresponding drivers into the kernel.
 * To compile this driver as a module, choose M here and read <file:Documentation/parport.txt>. The module will be called lp.
 * If you have several parallel ports, you can specify which ports to use with the "lp" kernel command line option. (Try "man bootparam" or see the documentation of your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.)  The syntax of the lp command line option can be found in <file:drivers/char/lp.c>.
 * If you have more than 8 printers, you need to increase the LP_NO macro in lp.c and the PARPORT_MAX macro in parport.h.


 * Option: LP_CONSOLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Support for console on line printer
 * depends on PRINTER
 * If you want kernel messages to be printed out as they occur, you can have a console on the printer. This option adds support for doing that; to actually get it to happen you need to pass the option "console=lp0" to the kernel at boot time.
 * If the printer is out of paper (or off, or unplugged, or too busy..) the kernel will stall until the printer is ready again. By defining CONSOLE_LP_STRICT to 0 (at your own risk) you can make the kernel continue when this happens, but it'll lose the kernel messages.
 * If unsure, say N.


 * Option: PPDEV
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Support for user-space parallel port device drivers
 * depends on PARPORT
 * Saying Y to this adds support for /dev/parport device nodes. This is needed for programs that want portable access to the parallel port, for instance deviceid (which displays Plug-and-Play device IDs).
 * This is the parallel port equivalent of SCSI generic support (sg). It is safe to say N to this—it is not needed for normal printing or parallel port CD-ROM/disk support.
 * To compile this driver as a module, choose M here: the module will be called ppdev.
 * If unsure, say N.


 * Option: TIPAR
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Texas Instruments parallel link cable support
 * depends on PARPORT
 * If you own a Texas Instruments graphing calculator and use a parallel link cable, then you might be interested in this driver.
 * If you enable this driver, you will be able to communicate with your calculator through a set of device nodes under /dev. The main advantage of this driver is that you don't have to be root to use this precise link cable (depending on the permissions on the device nodes, though).
 * To compile this driver as a module, choose M here: the module will be called tipar.
 * If you don't know what a parallel link cable is or what a Texas Instruments graphing calculator is, then you probably don't need this driver.
 * If unsure, say N.


 * Option: HVC_CONSOLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) pSeries Hypervisor Virtual Console support
 * depends on PPC_PSERIES
 * pSeries machines when partitioned support a hypervisor virtual console. This driver allows each pSeries partition to have a console which is accessed via the HMC.


 * Option: HVCS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) IBM Hypervisor Virtual Console Server support
 * depends on PPC_PSERIES
 * Partitionable IBM Power5 ppc64 machines allow hosting of firmware virtual consoles from one Linux partition by another Linux partition. This driver allows console data from Linux partitions to be accessed through TTY device interfaces in the device tree of a Linux partition running this driver.
 * To compile this driver as a module, choose M here: the module will be called hvcs.ko. Additionally, this module will depend on arch specific APIs exported from hvcserver.ko which will also be compiled when this driver is built as a module.


 * Option: Howto configure the Linux kernel/drivers/char/ipmi


 * Option: Howto configure the Linux kernel/drivers/char/watchdog


 * Option: DS1620
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) NetWinder thermometer support
 * depends on ARCH_NETWINDER
 * Say Y here to include support for the thermal management hardware found in the NetWinder. This driver allows the user to control the temperature set points and to read the current temperature.
 * It is also possible to say M here to build it as a module (ds1620) It is recommended to be used on a NetWinder, but it is not a necessity.


 * Option: NWBUTTON
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) NetWinder Button
 * depends on ARCH_NETWINDER
 * If you say Y here and create a character device node /dev/nwbutton with major and minor numbers 10 and 158 ("man mknod"), then every time the orange button is pressed a number of times, the number of times the button was pressed will be written to that device.
 * This is most useful for applications, as yet unwritten, which perform actions based on how many times the button is pressed in a row.
 * Do not hold the button down for too long, as the driver does not alter the behaviour of the hardware reset circuitry attached to the button; it will still execute a hard reset if the button is held down for longer than approximately five seconds.
 * To compile this driver as a module, choose M here: the module will be called nwbutton.
 * Most people will answer Y to this question and "Reboot Using Button" below to be able to initiate a system shutdown from the button.


 * Option: NWBUTTON_REBOOT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Reboot Using Button
 * depends on NWBUTTON
 * If you say Y here, then you will be able to initiate a system shutdown and reboot by pressing the orange button a number of times. The number of presses to initiate the shutdown is two by default, but this can be altered by modifying the value of NUM_PRESSES_REBOOT in nwbutton.h and recompiling the driver or, if you compile the driver as a module, you can specify the number of presses at load time with "insmod button reboot_count= ".


 * Option: NWFLASH
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) NetWinder flash support
 * depends on ARCH_NETWINDER
 * If you say Y here and create a character device /dev/flash with major 10 and minor 160 you can manipulate the flash ROM containing the NetWinder firmware. Be careful as accidentally overwriting the flash contents can render your computer unbootable. On no account allow random users access to this device. :-)
 * To compile this driver as a module, choose M here: the module will be called nwflash.
 * If you're not sure, say N.


 * Option: HW_RANDOM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Intel/AMD/VIA HW Random Number Generator support
 * depends on (X86 || IA64) && PCI
 * This driver provides kernel-side support for the Random Number Generator hardware found on Intel i8xx-based motherboards, AMD 76x-based motherboards, and Via Nehemiah CPUs.
 * Provides a character driver, used to read entropy data.
 * To compile this driver as a module, choose M here: the module will be called hw_random.
 * If unsure, say N.


 * Option: NVRAM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) /dev/nvram support
 * depends on ATARI || X86 || ARM || GENERIC_NVRAM
 * If you say Y here and create a character special file /dev/nvram with major number 10 and minor number 144 using mknod ("man mknod"), you get read and write access to the extra bytes of non-volatile memory in the real time clock (RTC), which is contained in every PC and most Ataris. The actual number of bytes varies, depending on the nvram in the system, but is usually 114 (128-14 for the RTC).
 * This memory is conventionally called "CMOS RAM" on PCs and "NVRAM" on Ataris. /dev/nvram may be used to view settings there, or to change them (with some utility). It could also be used to frequently save a few bits of very important data that may not be lost over power-off and for which writing to disk is too insecure. Note however that most NVRAM space in a PC belongs to the BIOS and you should NEVER idly tamper with it. See Ralf Brown's interrupt list for a guide to the use of CMOS bytes by your BIOS.
 * On Atari machines, /dev/nvram is always configured and does not need to be selected.
 * To compile this driver as a module, choose M here: the module will be called nvram.


 * Option: RTC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Enhanced Real Time Clock Support
 * depends on !PPC32 && !PARISC && !IA64 && !M68K && (!SPARC || PCI)
 * If you say Y here and create a character special file /dev/rtc with major number 10 and minor number 135 using mknod ("man mknod"), you will get access to the real time clock (or hardware clock) built into your computer.
 * Every PC has such a clock built in. It can be used to generate signals from as low as 1 Hz up to 8192 Hz, and can also be used as a 24 hour alarm. It reports status information via the file /proc/driver/rtc and its behaviour is set by various ioctls on /dev/rtc.
 * If you run Linux on a multiprocessor machine and said Y to Symmetric Multi Processing above, you should say Y here to read and set the RTC in an SMP compatible fashion.
 * If you think you have a use for such a device (such as periodic data sampling), then say Y here, and read <file:Documentation/rtc.txt> for details.
 * To compile this driver as a module, choose M here: the module will be called rtc.


 * Option: SGI_DS1286
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) SGI DS1286 RTC support
 * depends on SGI_IP22
 * If you say Y here and create a character special file /dev/rtc with major number 10 and minor number 135 using mknod ("man mknod"), you will get access to the real time clock built into your computer. Every SGI has such a clock built in. It reports status information via the file /proc/rtc and its behaviour is set by various ioctls on /dev/rtc.


 * Option: SGI_IP27_RTC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) SGI M48T35 RTC support
 * depends on SGI_IP27
 * If you say Y here and create a character special file /dev/rtc with major number 10 and minor number 135 using mknod ("man mknod"), you will get access to the real time clock built into your computer. Every SGI has such a clock built in. It reports status information via the file /proc/rtc and its behaviour is set by various ioctls on /dev/rtc.


 * Option: GEN_RTC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Generic /dev/rtc emulation
 * depends on RTC!=y && !IA64 && !ARM && !M32R && !SPARC
 * If you say Y here and create a character special file /dev/rtc with major number 10 and minor number 135 using mknod ("man mknod"), you will get access to the real time clock (or hardware clock) built into your computer.
 * It reports status information via the file /proc/driver/rtc and its behaviour is set by various ioctls on /dev/rtc. If you enable the extended RTC operation below it will also provide an emulation for RTC_UIE which is required by some programs and may improve precision in some cases.
 * To compile this driver as a module, choose M here: the module will be called genrtc.


 * Option: GEN_RTC_X
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Extended RTC operation
 * depends on GEN_RTC
 * Provides an emulation for RTC_UIE which is required by some programs and may improve precision of the generic RTC support in some cases.


 * Option: EFI_RTC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) EFI Real Time Clock Services
 * depends on IA64


 * Option: DS1302
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) DS1302 RTC support
 * depends on M32R && (PLAT_M32700UT || PLAT_OPSPUT)
 * If you say Y here and create a character special file /dev/rtc with major number 121 and minor number 0 using mknod ("man mknod"), you will get access to the real time clock (or hardware clock) built into your computer.


 * Option: S3C2410_RTC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) S3C2410 RTC Driver
 * depends on ARCH_S3C2410
 * RTC (Realtime Clock) driver for the clock inbuilt into the Samsung S3C2410. This can provide periodic interrupt rates from 1 Hz to 64 Hz for user programs, and wakeup from Alarm.


 * Option: RTC_VR41XX
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) NEC VR4100 series Real Time Clock Support
 * depends on CPU_VR41XX


 * Option: COBALT_LCD
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Support for Cobalt LCD
 * depends on MIPS_COBALT
 * This option enables support for the LCD display and buttons found on Cobalt systems through a misc device.


 * Option: DTLK
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Double Talk PC internal speech card support
 * This driver is for the DoubleTalk PC, a speech synthesizer manufactured by RC Systems (<http://www.rcsys.com/>). It is also called the `internal DoubleTalk'.
 * To compile this driver as a module, choose M here: the module will be called dtlk.


 * Option: R3964
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Siemens R3964 line discipline
 * This driver allows synchronous communication with devices using the Siemens R3964 packet protocol. Unless you are dealing with special hardware like PLCs, you are unlikely to need this.
 * To compile this driver as a module, choose M here: the module will be called n_r3964.
 * If unsure, say N.


 * Option: APPLICOM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Applicom intelligent fieldbus card support
 * depends on PCI
 * This driver provides the kernel-side support for the intelligent fieldbus cards made by Applicom International. More information about these cards can be found on the WWW at the address <http://www.applicom-int.com/>, or by email from David Woodhouse <dwmw2@infradead.org>.
 * To compile this driver as a module, choose M here: the module will be called applicom.
 * If unsure, say N.


 * Option: SONYPI
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Sony Vaio Programmable I/O Control Device support (EXPERIMENTAL)
 * depends on EXPERIMENTAL && X86 && PCI && INPUT && !64BIT
 * This driver enables access to the Sony Programmable I/O Control Device which can be found in many (all ?) Sony Vaio laptops.
 * If you have one of those laptops, read <file:Documentation/sonypi.txt>, and say Y or M here.
 * To compile this driver as a module, choose M here: the module will be called sonypi.


 * Option: TANBAC_TB0219
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) TANBAC TB0219 base board support
 * depends TANBAC_TB022X

Ftape, the floppy tape device driver

 * Option: FTAPE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Ftape (QIC-80/Travan) support
 * depends on BROKEN_ON_SMP && (ALPHA || X86)
 * If you have a tape drive that is connected to your floppy controller, say Y here.
 * Some tape drives (like the Seagate "Tape Store 3200" or the Iomega Ditto 3200 or the Exabyte Eagle TR-3) come with a high speed controller of their own. These drives (and their companion controllers) are also supported if you say Y here.
 * If you have a special controller (such as the CMS FC-10, FC-20, Mountain Mach-II, or any controller that is based on the Intel 82078 FDC like the high speed controllers by Seagate and Exabyte and Iomega's "Ditto Dash") you must configure it by selecting the appropriate entries from the "Floppy tape controllers" sub-menu below and possibly modify the default values for the IRQ and DMA channel and the IO base in ftape's configuration menu.
 * If you want to use your floppy tape drive on a PCI-bus based system, please read the file <file:drivers/char/ftape/README.PCI>.
 * The ftape kernel driver is also available as a runtime loadable module. To compile this driver as a module, choose M here: the module will be called ftape.
 * Note that the Ftape-HOWTO is out of date (sorry) and documents the older version 2.08 of this software but still contains useful information. There is a web page with more recent documentation at <http://www.instmath.rwth-aachen.de/~heine/ftape/>.  This page always contains the latest release of the ftape driver and useful information (backup software, ftape related patches and documentation, FAQ).  Note that the file system interface has changed quite a bit compared to previous versions of ftape.  Please read <file:Documentation/ftape.txt>.


 * Option: Howto configure the Linux kernel/drivers/char/ftape


 * Option: Howto configure the Linux kernel/drivers/char/agp


 * Option: Howto configure the Linux kernel/drivers/char/drm


 * Option: Howto configure the Linux kernel/drivers/char/pcmcia


 * Option: MWAVE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) ACP Modem (Mwave) support
 * depends on X86
 * select SERIAL_8250
 * The ACP modem (Mwave) for Linux is a WinModem. It is composed of a kernel driver and a user level application. Together these components support direct attachment to public switched telephone networks (PSTNs) and support selected world wide countries.
 * This version of the ACP Modem driver supports the IBM Thinkpad 600E, 600, and 770 that include on board ACP modem hardware.
 * The modem also supports the standard communications port interface (ttySx) and is compatible with the Hayes AT Command Set.
 * The user level application needed to use this driver can be found at the IBM Linux Technology Center (LTC) web site: <http://www.ibm.com/linux/ltc/>.
 * If you own one of the above IBM Thinkpads which has the Mwave chipset in it, say Y.
 * To compile this driver as a module, choose M here: the module will be called mwave.


 * Option: SCx200_GPIO
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) NatSemi SCx200 GPIO Support
 * depends on SCx200
 * Give userspace access to the GPIO pins on the National Semiconductor SCx200 processors.
 * If compiled as a module, it will be called scx200_gpio.


 * Option: GPIO_VR41XX
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) NEC VR4100 series General-purpose I/O Unit support
 * depends on CPU_VR41XX


 * Option: RAW_DRIVER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) RAW driver (/dev/raw/rawN) (OBSOLETE)
 * The raw driver permits block devices to be bound to /dev/raw/rawN. Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.  See the raw(8) manpage for more details.
 * The raw driver is deprecated and will be removed soon.        Applications should simply open the device (e.g. /dev/hda1)         with the O_DIRECT flag.

"Maximum number of RAW devices to support (1-8192)"
 * Option: MAX_RAW_DEVS
 * Kernel Versions: 2.6.15.6 ...
 * depends on RAW_DRIVER
 * default "256"
 * The maximum number of RAW devices that are supported. Default is 256. Increase this number in case you need lots of raw devices.


 * Option: HPET
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) HPET - High Precision Event Timer if (X86 || IA64)
 * default n
 * depends on ACPI
 * If you say Y here, you will have a miscdevice named "/dev/hpet/". Each open selects one of the timers supported by the HPET.  The timers are non-periodioc and/or periodic.


 * Option: HPET_RTC_IRQ
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) HPET Control RTC IRQ if !HPET_EMULATE_RTC
 * default n
 * depends on HPET
 * If you say Y here, you will disable RTC_IRQ in drivers/char/rtc.c. It is assumed the platform called hpet_alloc with the RTC IRQ values for the HPET timers.


 * Option: HPET_MMAP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Allow mmap of HPET
 * default y
 * depends on HPET
 * If you say Y here, user applications will be able to mmap the HPET registers.
 * In some hardware implementations, the page containing HPET registers may also contain other things that shouldn't be exposed to the user. If this applies to your hardware, say N here.


 * Option: HANGCHECK_TIMER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Hangcheck timer
 * depends on X86 || IA64 || PPC64 || ARCH_S390
 * The hangcheck-timer module detects when the system has gone out to lunch past a certain margin. It can reboot the system or merely print a warning.


 * Option: MMTIMER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) MMTIMER Memory mapped RTC for SGI Altix
 * depends on IA64_GENERIC || IA64_SGI_SN2
 * default y
 * The mmtimer device allows direct userspace access to the Altix system timer.


 * Option: Howto configure the Linux kernel/drivers/char/tpm


 * Option: TELCLOCK
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Telecom clock driver for MPBL0010 ATCA SBC
 * depends on EXPERIMENTAL
 * default n
 * The telecom clock device is specific to the MPBL0010 ATCA computer and allows direct userspace access to the configuration of the telecom clock configuration settings. This device is used for hardware synchronization across the ATCA backplane fabric.  Upon loading, the driver exports a sysfs directory, /sys/devices/platform/telco_clock, with a number of files for controlling the behavior of this hardware.

Linux Kernel Configuration