drivers/tty/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0
   2 config TTY
   3         bool "Enable TTY" if EXPERT
   4         default y
   5         ---help---
   6           Allows you to remove TTY support which can save space, and
   7           blocks features that require TTY from inclusion in the kernel.
   8           TTY is required for any text terminals or serial port
   9           communication. Most users should leave this enabled.
  10
  11 if TTY
  12
  13 config VT
  14         bool "Virtual terminal" if EXPERT
  15         depends on !UML
  16         select INPUT
  17         default y
  18         ---help---
  19           If you say Y here, you will get support for terminal devices with
  20           display and keyboard devices. These are called "virtual" because you
  21           can run several virtual terminals (also called virtual consoles) on
  22           one physical terminal. This is rather useful, for example one
  23           virtual terminal can collect system messages and warnings, another
  24           one can be used for a text-mode user session, and a third could run
  25           an X session, all in parallel. Switching between virtual terminals
  26           is done with certain key combinations, usually Alt-<function key>.
  27
  28           The setterm command ("man setterm") can be used to change the
  29           properties (such as colors or beeping) of a virtual terminal. The
  30           man page console_codes(4) ("man console_codes") contains the special
  31           character sequences that can be used to change those properties
  32           directly. The fonts used on virtual terminals can be changed with
  33           the setfont ("man setfont") command and the key bindings are defined
  34           with the loadkeys ("man loadkeys") command.
  35
  36           You need at least one virtual terminal device in order to make use
  37           of your keyboard and monitor. Therefore, only people configuring an
  38           embedded system would want to say N here in order to save some
  39           memory; the only way to log into such a system is then via a serial
  40           or network connection.
  41
  42           If unsure, say Y, or else you won't be able to do much with your new
  43           shiny Linux system :-)
  44
  45 config CONSOLE_TRANSLATIONS
  46         depends on VT
  47         default y
  48         bool "Enable character translations in console" if EXPERT
  49         ---help---
  50           This enables support for font mapping and Unicode translation
  51           on virtual consoles.
  52
  53 config VT_CONSOLE
  54         bool "Support for console on virtual terminal" if EXPERT
  55         depends on VT
  56         default y
  57         ---help---
  58           The system console is the device which receives all kernel messages
  59           and warnings and which allows logins in single user mode. If you
  60           answer Y here, a virtual terminal (the device used to interact with
  61           a physical terminal) can be used as system console. This is the most
  62           common mode of operations, so you should say Y here unless you want
  63           the kernel messages be output only to a serial port (in which case
  64           you should say Y to "Console on serial port", below).
  65
  66           If you do say Y here, by default the currently visible virtual
  67           terminal (/dev/tty0) will be used as system console. You can change
  68           that with a kernel command line option such as "console=tty3" which
  69           would use the third virtual terminal as system console. (Try "man
  70           bootparam" or see the documentation of your boot loader (lilo or
  71           loadlin) about how to pass options to the kernel at boot time.)
  72
  73           If unsure, say Y.
  74
  75 config VT_CONSOLE_SLEEP
  76         def_bool y
  77         depends on VT_CONSOLE && PM_SLEEP
  78
  79 config HW_CONSOLE
  80         bool
  81         depends on VT && !UML
  82         default y
  83
  84 config VT_HW_CONSOLE_BINDING
  85         bool "Support for binding and unbinding console drivers"
  86         depends on HW_CONSOLE
  87         ---help---
  88           The virtual terminal is the device that interacts with the physical
  89           terminal through console drivers. On these systems, at least one
  90           console driver is loaded. In other configurations, additional console
  91           drivers may be enabled, such as the framebuffer console. If more than
  92           1 console driver is enabled, setting this to 'y' will allow you to
  93           select the console driver that will serve as the backend for the
  94           virtual terminals.
  95
  96           See <file:Documentation/driver-api/console.rst> for more
  97           information. For framebuffer console users, please refer to
  98           <file:Documentation/fb/fbcon.rst>.
  99
 100 config UNIX98_PTYS
 101         bool "Unix98 PTY support" if EXPERT
 102         default y
 103         ---help---
 104           A pseudo terminal (PTY) is a software device consisting of two
 105           halves: a master and a slave. The slave device behaves identical to
 106           a physical terminal; the master device is used by a process to
 107           read data from and write data to the slave, thereby emulating a
 108           terminal. Typical programs for the master side are telnet servers
 109           and xterms.
 110
 111           Linux has traditionally used the BSD-like names /dev/ptyxx for
 112           masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
 113           has a number of problems. The GNU C library glibc 2.1 and later,
 114           however, supports the Unix98 naming standard: in order to acquire a
 115           pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
 116           terminal is then made available to the process and the pseudo
 117           terminal slave can be accessed as /dev/pts/<number>. What was
 118           traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
 119
 120           All modern Linux systems use the Unix98 ptys.  Say Y unless
 121           you're on an embedded system and want to conserve memory.
 122
 123 config LEGACY_PTYS
 124         bool "Legacy (BSD) PTY support"
 125         default y
 126         ---help---
 127           A pseudo terminal (PTY) is a software device consisting of two
 128           halves: a master and a slave. The slave device behaves identical to
 129           a physical terminal; the master device is used by a process to
 130           read data from and write data to the slave, thereby emulating a
 131           terminal. Typical programs for the master side are telnet servers
 132           and xterms.
 133
 134           Linux has traditionally used the BSD-like names /dev/ptyxx
 135           for masters and /dev/ttyxx for slaves of pseudo
 136           terminals. This scheme has a number of problems, including
 137           security.  This option enables these legacy devices; on most
 138           systems, it is safe to say N.
 139
 140
 141 config LEGACY_PTY_COUNT
 142         int "Maximum number of legacy PTY in use"
 143         depends on LEGACY_PTYS
 144         range 0 256
 145         default "256"
 146         ---help---
 147           The maximum number of legacy PTYs that can be used at any one time.
 148           The default is 256, and should be more than enough.  Embedded
 149           systems may want to reduce this to save memory.
 150
 151           When not in use, each legacy PTY occupies 12 bytes on 32-bit
 152           architectures and 24 bytes on 64-bit architectures.
 153
 154 config SERIAL_NONSTANDARD
 155         bool "Non-standard serial port support"
 156         depends on HAS_IOMEM
 157         ---help---
 158           Say Y here if you have any non-standard serial boards -- boards
 159           which aren't supported using the standard "dumb" serial driver.
 160           This includes intelligent serial boards such as Cyclades,
 161           Digiboards, etc. These are usually used for systems that need many
 162           serial ports because they serve many terminals or dial-in
 163           connections.
 164
 165           Note that the answer to this question won't directly affect the
 166           kernel: saying N will just cause the configurator to skip all
 167           the questions about non-standard serial boards.
 168
 169           Most people can say N here.
 170
 171 config ROCKETPORT
 172         tristate "Comtrol RocketPort support"
 173         depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
 174         help
 175           This driver supports Comtrol RocketPort and RocketModem PCI boards.
 176           These boards provide 2, 4, 8, 16, or 32 high-speed serial ports or
 177           modems.  For information about the RocketPort/RocketModem  boards
 178           and this driver read <file:Documentation/driver-api/serial/rocket.rst>.
 179
 180           To compile this driver as a module, choose M here: the
 181           module will be called rocket.
 182
 183           If you want to compile this driver into the kernel, say Y here.  If
 184           you don't have a Comtrol RocketPort/RocketModem card installed, say N.
 185
 186 config CYCLADES
 187         tristate "Cyclades async mux support"
 188         depends on SERIAL_NONSTANDARD && (PCI || ISA)
 189         select FW_LOADER
 190         ---help---
 191           This driver supports Cyclades Z and Y multiserial boards.
 192           You would need something like this to connect more than two modems to
 193           your Linux box, for instance in order to become a dial-in server.
 194
 195           For information about the Cyclades-Z card, read
 196           <file:Documentation/driver-api/serial/cyclades_z.rst>.
 197
 198           To compile this driver as a module, choose M here: the
 199           module will be called cyclades.
 200
 201           If you haven't heard about it, it's safe to say N.
 202
 203 config CYZ_INTR
 204         bool "Cyclades-Z interrupt mode operation"
 205         depends on CYCLADES && PCI
 206         help
 207           The Cyclades-Z family of multiport cards allows 2 (two) driver op
 208           modes: polling and interrupt. In polling mode, the driver will check
 209           the status of the Cyclades-Z ports every certain amount of time
 210           (which is called polling cycle and is configurable). In interrupt
 211           mode, it will use an interrupt line (IRQ) in order to check the
 212           status of the Cyclades-Z ports. The default op mode is polling. If
 213           unsure, say N.
 214
 215 config MOXA_INTELLIO
 216         tristate "Moxa Intellio support"
 217         depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
 218         select FW_LOADER
 219         help
 220           Say Y here if you have a Moxa Intellio multiport serial card.
 221
 222           To compile this driver as a module, choose M here: the
 223           module will be called moxa.
 224
 225 config MOXA_SMARTIO
 226         tristate "Moxa SmartIO support v. 2.0"
 227         depends on SERIAL_NONSTANDARD && (PCI || EISA || ISA)
 228         help
 229           Say Y here if you have a Moxa SmartIO multiport serial card and/or
 230           want to help develop a new version of this driver.
 231
 232           This is upgraded (1.9.1) driver from original Moxa drivers with
 233           changes finally resulting in PCI probing.
 234
 235           This driver can also be built as a module. The module will be called
 236           mxser. If you want to do that, say M here.
 237
 238 config SYNCLINK
 239         tristate "Microgate SyncLink card support"
 240         depends on SERIAL_NONSTANDARD && PCI && ISA_DMA_API
 241         help
 242           Provides support for the SyncLink ISA and PCI multiprotocol serial
 243           adapters. These adapters support asynchronous and HDLC bit
 244           synchronous communication up to 10Mbps (PCI adapter).
 245
 246           This driver can only be built as a module ( = code which can be
 247           inserted in and removed from the running kernel whenever you want).
 248           The module will be called synclink.  If you want to do that, say M
 249           here.
 250
 251 config SYNCLINKMP
 252         tristate "SyncLink Multiport support"
 253         depends on SERIAL_NONSTANDARD && PCI
 254         help
 255           Enable support for the SyncLink Multiport (2 or 4 ports)
 256           serial adapter, running asynchronous and HDLC communications up
 257           to 2.048Mbps. Each ports is independently selectable for
 258           RS-232, V.35, RS-449, RS-530, and X.21
 259
 260           This driver may be built as a module ( = code which can be
 261           inserted in and removed from the running kernel whenever you want).
 262           The module will be called synclinkmp.  If you want to do that, say M
 263           here.
 264
 265 config SYNCLINK_GT
 266         tristate "SyncLink GT/AC support"
 267         depends on SERIAL_NONSTANDARD && PCI
 268         help
 269           Support for SyncLink GT and SyncLink AC families of
 270           synchronous and asynchronous serial adapters
 271           manufactured by Microgate Systems, Ltd. (www.microgate.com)
 272
 273 config NOZOMI
 274         tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
 275         depends on PCI
 276         help
 277           If you have a HSDPA driver Broadband Wireless Data Card -
 278           Globe Trotter PCMCIA card, say Y here.
 279
 280           To compile this driver as a module, choose M here, the module
 281           will be called nozomi.
 282
 283 config ISI
 284         tristate "Multi-Tech multiport card support"
 285         depends on SERIAL_NONSTANDARD && PCI
 286         select FW_LOADER
 287         help
 288           This is a driver for the Multi-Tech cards which provide several
 289           serial ports.  The driver is experimental and can currently only be
 290           built as a module. The module will be called isicom.
 291           If you want to do that, choose M here.
 292
 293 config N_HDLC
 294         tristate "HDLC line discipline support"
 295         depends on SERIAL_NONSTANDARD
 296         help
 297           Allows synchronous HDLC communications with tty device drivers that
 298           support synchronous HDLC such as the Microgate SyncLink adapter.
 299
 300           This driver can be built as a module ( = code which can be
 301           inserted in and removed from the running kernel whenever you want).
 302           The module will be called n_hdlc. If you want to do that, say M
 303           here.
 304
 305 config N_GSM
 306         tristate "GSM MUX line discipline support (EXPERIMENTAL)"
 307         depends on NET
 308         help
 309           This line discipline provides support for the GSM MUX protocol and
 310           presents the mux as a set of 61 individual tty devices.
 311
 312 config TRACE_ROUTER
 313         tristate "Trace data router for MIPI P1149.7 cJTAG standard"
 314         depends on TRACE_SINK
 315         help
 316           The trace router uses the Linux tty line discipline framework to
 317           route trace data coming from a tty port (say UART for example) to
 318           the trace sink line discipline driver and to another tty port (say
 319           USB). This is part of a solution for the MIPI P1149.7, compact JTAG,
 320           standard, which is for debugging mobile devices. The PTI driver in
 321           drivers/misc/pti.c defines the majority of this MIPI solution.
 322
 323           You should select this driver if the target kernel is meant for
 324           a mobile device containing a modem.  Then you will need to select
 325           "Trace data sink for MIPI P1149.7 cJTAG standard" line discipline
 326           driver.
 327
 328 config TRACE_SINK
 329         tristate "Trace data sink for MIPI P1149.7 cJTAG standard"
 330         help
 331           The trace sink uses the Linux line discipline framework to receive
 332           trace data coming from the trace router line discipline driver
 333           to a user-defined tty port target, like USB.
 334           This is to provide a way to extract modem trace data on
 335           devices that do not have a PTI HW module, or just need modem
 336           trace data to come out of a different HW output port.
 337           This is part of a solution for the P1149.7, compact JTAG, standard.
 338
 339           If you select this option, you need to select
 340           "Trace data router for MIPI P1149.7 cJTAG standard".
 341
 342 config PPC_EPAPR_HV_BYTECHAN
 343         bool "ePAPR hypervisor byte channel driver"
 344         depends on PPC
 345         select EPAPR_PARAVIRT
 346         help
 347           This driver creates /dev entries for each ePAPR hypervisor byte
 348           channel, thereby allowing applications to communicate with byte
 349           channels as if they were serial ports.
 350
 351 config PPC_EARLY_DEBUG_EHV_BC
 352         bool "Early console (udbg) support for ePAPR hypervisors"
 353         depends on PPC_EPAPR_HV_BYTECHAN=y
 354         help
 355           Select this option to enable early console (a.k.a. "udbg") support
 356           via an ePAPR byte channel.  You also need to choose the byte channel
 357           handle below.
 358
 359 config PPC_EARLY_DEBUG_EHV_BC_HANDLE
 360         int "Byte channel handle for early console (udbg)"
 361         depends on PPC_EARLY_DEBUG_EHV_BC
 362         default 0
 363         help
 364           If you want early console (udbg) output through a byte channel,
 365           specify the handle of the byte channel to use.
 366
 367           For this to work, the byte channel driver must be compiled
 368           in-kernel, not as a module.
 369
 370           Note that only one early console driver can be enabled, so don't
 371           enable any others if you enable this one.
 372
 373           If the number you specify is not a valid byte channel handle, then
 374           there simply will be no early console output.  This is true also
 375           if you don't boot under a hypervisor at all.
 376
 377 config NULL_TTY
 378         tristate "NULL TTY driver"
 379         help
 380           Say Y here if you want a NULL TTY which simply discards messages.
 381
 382           This is useful to allow userspace applications which expect a console
 383           device to work without modifications even when no console is
 384           available or desired.
 385
 386           In order to use this driver, you should redirect the console to this
 387           TTY, or boot the kernel with console=ttynull.
 388
 389           If unsure, say N.
 390
 391 config GOLDFISH_TTY
 392         tristate "Goldfish TTY Driver"
 393         depends on GOLDFISH
 394         select SERIAL_CORE
 395         select SERIAL_CORE_CONSOLE
 396         help
 397           Console and system TTY driver for the Goldfish virtual platform.
 398
 399 config GOLDFISH_TTY_EARLY_CONSOLE
 400         bool
 401         default y if GOLDFISH_TTY=y
 402         select SERIAL_EARLYCON
 403
 404 config MIPS_EJTAG_FDC_TTY
 405         bool "MIPS EJTAG Fast Debug Channel TTY"
 406         depends on MIPS_CDMM
 407         help
 408           This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
 409           if they are present. This can be useful when working with an EJTAG
 410           probe which supports it, to get console output and a login prompt via
 411           EJTAG without needing to connect a serial cable.
 412
 413           TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
 414           CPU3).
 415
 416           The console can be enabled with console=fdc1 (for FDC channel 1 on all
 417           CPUs). Do not use the console unless there is a debug probe attached
 418           to drain the FDC TX FIFO.
 419
 420           If unsure, say N.
 421
 422 config MIPS_EJTAG_FDC_EARLYCON
 423         bool "Early FDC console"
 424         depends on MIPS_EJTAG_FDC_TTY
 425         help
 426           This registers a console on FDC channel 1 very early during boot (from
 427           MIPS arch code). This is useful for bring-up and debugging early boot
 428           issues.
 429
 430           Do not enable unless there is a debug probe attached to drain the FDC
 431           TX FIFO.
 432
 433           If unsure, say N.
 434
 435 config MIPS_EJTAG_FDC_KGDB
 436         bool "Use KGDB over an FDC channel"
 437         depends on MIPS_EJTAG_FDC_TTY && KGDB
 438         default y
 439         help
 440           This enables the use of KGDB over an FDC channel, allowing KGDB to be
 441           used remotely or when a serial port isn't available.
 442
 443 config MIPS_EJTAG_FDC_KGDB_CHAN
 444         int "KGDB FDC channel"
 445         depends on MIPS_EJTAG_FDC_KGDB
 446         range 2 15
 447         default 3
 448         help
 449           FDC channel number to use for KGDB.
 450
 451 config VCC
 452         tristate "Sun Virtual Console Concentrator"
 453         depends on SUN_LDOMS
 454         help
 455           Support for Sun logical domain consoles.
 456
 457 config LDISC_AUTOLOAD
 458         bool "Automatically load TTY Line Disciplines"
 459         default y
 460         help
 461           Historically the kernel has always automatically loaded any
 462           line discipline that is in a kernel module when a user asks
 463           for it to be loaded with the TIOCSETD ioctl, or through other
 464           means.  This is not always the best thing to do on systems
 465           where you know you will not be using some of the more
 466           "ancient" line disciplines, so prevent the kernel from doing
 467           this unless the request is coming from a process with the
 468           CAP_SYS_MODULE permissions.
 469
 470           Say 'Y' here if you trust your userspace users to do the right
 471           thing, or if you have only provided the line disciplines that
 472           you know you will be using, or if you wish to continue to use
 473           the traditional method of on-demand loading of these modules
 474           by any user.
 475
 476           This functionality can be changed at runtime with the
 477           dev.tty.ldisc_autoload sysctl, this configuration option will
 478           only set the default value of this functionality.
 479
 480 endif # TTY