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 config LEGACY_PTY_COUNT
 141         int "Maximum number of legacy PTY in use"
 142         depends on LEGACY_PTYS
 143         range 0 256
 144         default "256"
 145         help
 146           The maximum number of legacy PTYs that can be used at any one time.
 147           The default is 256, and should be more than enough.  Embedded
 148           systems may want to reduce this to save memory.
 149
 150           When not in use, each legacy PTY occupies 12 bytes on 32-bit
 151           architectures and 24 bytes on 64-bit architectures.
 152
 153 config LDISC_AUTOLOAD
 154         bool "Automatically load TTY Line Disciplines"
 155         default y
 156         help
 157           Historically the kernel has always automatically loaded any
 158           line discipline that is in a kernel module when a user asks
 159           for it to be loaded with the TIOCSETD ioctl, or through other
 160           means.  This is not always the best thing to do on systems
 161           where you know you will not be using some of the more
 162           "ancient" line disciplines, so prevent the kernel from doing
 163           this unless the request is coming from a process with the
 164           CAP_SYS_MODULE permissions.
 165
 166           Say 'Y' here if you trust your userspace users to do the right
 167           thing, or if you have only provided the line disciplines that
 168           you know you will be using, or if you wish to continue to use
 169           the traditional method of on-demand loading of these modules
 170           by any user.
 171
 172           This functionality can be changed at runtime with the
 173           dev.tty.ldisc_autoload sysctl, this configuration option will
 174           only set the default value of this functionality.
 175
 176 source "drivers/tty/serial/Kconfig"
 177
 178 config SERIAL_NONSTANDARD
 179         bool "Non-standard serial port support"
 180         depends on HAS_IOMEM
 181         help
 182           Say Y here if you have any non-standard serial boards -- boards
 183           which aren't supported using the standard "dumb" serial driver.
 184           This includes intelligent serial boards such as
 185           Digiboards, etc. These are usually used for systems that need many
 186           serial ports because they serve many terminals or dial-in
 187           connections.
 188
 189           Note that the answer to this question won't directly affect the
 190           kernel: saying N will just cause the configurator to skip all
 191           the questions about non-standard serial boards.
 192
 193           Most people can say N here.
 194
 195 config MOXA_INTELLIO
 196         tristate "Moxa Intellio support"
 197         depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI)
 198         select FW_LOADER
 199         help
 200           Say Y here if you have a Moxa Intellio multiport serial card.
 201
 202           To compile this driver as a module, choose M here: the
 203           module will be called moxa.
 204
 205 config MOXA_SMARTIO
 206         tristate "Moxa SmartIO support v. 2.0"
 207         depends on SERIAL_NONSTANDARD && (PCI || EISA || ISA)
 208         help
 209           Say Y here if you have a Moxa SmartIO multiport serial card and/or
 210           want to help develop a new version of this driver.
 211
 212           This is upgraded (1.9.1) driver from original Moxa drivers with
 213           changes finally resulting in PCI probing.
 214
 215           This driver can also be built as a module. The module will be called
 216           mxser. If you want to do that, say M here.
 217
 218 config SYNCLINK_GT
 219         tristate "SyncLink GT/AC support"
 220         depends on SERIAL_NONSTANDARD && PCI
 221         help
 222           Support for SyncLink GT and SyncLink AC families of
 223           synchronous and asynchronous serial adapters
 224           manufactured by Microgate Systems, Ltd. (www.microgate.com)
 225
 226 config N_HDLC
 227         tristate "HDLC line discipline support"
 228         depends on SERIAL_NONSTANDARD
 229         help
 230           Allows synchronous HDLC communications with tty device drivers that
 231           support synchronous HDLC such as the Microgate SyncLink adapter.
 232
 233           This driver can be built as a module ( = code which can be
 234           inserted in and removed from the running kernel whenever you want).
 235           The module will be called n_hdlc. If you want to do that, say M
 236           here.
 237
 238 config PPC_EPAPR_HV_BYTECHAN
 239         bool "ePAPR hypervisor byte channel driver"
 240         depends on PPC
 241         select EPAPR_PARAVIRT
 242         help
 243           This driver creates /dev entries for each ePAPR hypervisor byte
 244           channel, thereby allowing applications to communicate with byte
 245           channels as if they were serial ports.
 246
 247 config PPC_EARLY_DEBUG_EHV_BC
 248         bool "Early console (udbg) support for ePAPR hypervisors"
 249         depends on PPC_EPAPR_HV_BYTECHAN=y
 250         help
 251           Select this option to enable early console (a.k.a. "udbg") support
 252           via an ePAPR byte channel.  You also need to choose the byte channel
 253           handle below.
 254
 255 config PPC_EARLY_DEBUG_EHV_BC_HANDLE
 256         int "Byte channel handle for early console (udbg)"
 257         depends on PPC_EARLY_DEBUG_EHV_BC
 258         default 0
 259         help
 260           If you want early console (udbg) output through a byte channel,
 261           specify the handle of the byte channel to use.
 262
 263           For this to work, the byte channel driver must be compiled
 264           in-kernel, not as a module.
 265
 266           Note that only one early console driver can be enabled, so don't
 267           enable any others if you enable this one.
 268
 269           If the number you specify is not a valid byte channel handle, then
 270           there simply will be no early console output.  This is true also
 271           if you don't boot under a hypervisor at all.
 272
 273 config GOLDFISH_TTY
 274         tristate "Goldfish TTY Driver"
 275         depends on GOLDFISH
 276         select SERIAL_CORE
 277         select SERIAL_CORE_CONSOLE
 278         help
 279           Console and system TTY driver for the Goldfish virtual platform.
 280
 281 config GOLDFISH_TTY_EARLY_CONSOLE
 282         bool
 283         default y if GOLDFISH_TTY=y
 284         select SERIAL_EARLYCON
 285
 286 config N_GSM
 287         tristate "GSM MUX line discipline support (EXPERIMENTAL)"
 288         depends on NET
 289         help
 290           This line discipline provides support for the GSM MUX protocol and
 291           presents the mux as a set of 61 individual tty devices.
 292
 293 config NOZOMI
 294         tristate "HSDPA Broadband Wireless Data Card - Globe Trotter"
 295         depends on PCI
 296         help
 297           If you have a HSDPA driver Broadband Wireless Data Card -
 298           Globe Trotter PCMCIA card, say Y here.
 299
 300           To compile this driver as a module, choose M here, the module
 301           will be called nozomi.
 302
 303 config MIPS_EJTAG_FDC_TTY
 304         bool "MIPS EJTAG Fast Debug Channel TTY"
 305         depends on MIPS_CDMM
 306         help
 307           This enables a TTY and console on the MIPS EJTAG Fast Debug Channels,
 308           if they are present. This can be useful when working with an EJTAG
 309           probe which supports it, to get console output and a login prompt via
 310           EJTAG without needing to connect a serial cable.
 311
 312           TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on
 313           CPU3).
 314
 315           The console can be enabled with console=fdc1 (for FDC channel 1 on all
 316           CPUs). Do not use the console unless there is a debug probe attached
 317           to drain the FDC TX FIFO.
 318
 319           If unsure, say N.
 320
 321 config MIPS_EJTAG_FDC_EARLYCON
 322         bool "Early FDC console"
 323         depends on MIPS_EJTAG_FDC_TTY
 324         help
 325           This registers a console on FDC channel 1 very early during boot (from
 326           MIPS arch code). This is useful for bring-up and debugging early boot
 327           issues.
 328
 329           Do not enable unless there is a debug probe attached to drain the FDC
 330           TX FIFO.
 331
 332           If unsure, say N.
 333
 334 config MIPS_EJTAG_FDC_KGDB
 335         bool "Use KGDB over an FDC channel"
 336         depends on MIPS_EJTAG_FDC_TTY && KGDB
 337         default y
 338         help
 339           This enables the use of KGDB over an FDC channel, allowing KGDB to be
 340           used remotely or when a serial port isn't available.
 341
 342 config MIPS_EJTAG_FDC_KGDB_CHAN
 343         int "KGDB FDC channel"
 344         depends on MIPS_EJTAG_FDC_KGDB
 345         range 2 15
 346         default 3
 347         help
 348           FDC channel number to use for KGDB.
 349
 350 config NULL_TTY
 351         tristate "NULL TTY driver"
 352         help
 353           Say Y here if you want a NULL TTY which simply discards messages.
 354
 355           This is useful to allow userspace applications which expect a console
 356           device to work without modifications even when no console is
 357           available or desired.
 358
 359           In order to use this driver, you should redirect the console to this
 360           TTY, or boot the kernel with console=ttynull.
 361
 362           If unsure, say N.
 363
 364 config VCC
 365         tristate "Sun Virtual Console Concentrator"
 366         depends on SUN_LDOMS
 367         help
 368           Support for Sun logical domain consoles.
 369
 370 source "drivers/tty/hvc/Kconfig"
 371
 372 endif # TTY
 373
 374 source "drivers/tty/serdev/Kconfig"