1# SPDX-License-Identifier: GPL-2.0 2config 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 11if TTY 12 13config 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 45config 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 53config 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 75config VT_CONSOLE_SLEEP 76 def_bool y 77 depends on VT_CONSOLE && PM_SLEEP 78 79config HW_CONSOLE 80 bool 81 depends on VT && !UML 82 default y 83 84config 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 100config 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 123config 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 140config 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 153config 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 176source "drivers/tty/serial/Kconfig" 177 178config 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 195config 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 205config 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 218config 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 226config 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 238config 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 247config 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 255config 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 273config 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 281config GOLDFISH_TTY_EARLY_CONSOLE 282 bool 283 default y if GOLDFISH_TTY=y 284 select SERIAL_EARLYCON 285 286config 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 293config 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 303config 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 321config 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 334config 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 342config 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 350config 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 364config VCC 365 tristate "Sun Virtual Console Concentrator" 366 depends on SUN_LDOMS 367 help 368 Support for Sun logical domain consoles. 369 370source "drivers/tty/hvc/Kconfig" 371 372endif # TTY 373 374source "drivers/tty/serdev/Kconfig" 375