| # SPDX-License-Identifier: GPL-2.0 |
| config TTY |
| bool "Enable TTY" if EXPERT |
| default y |
| help |
| Allows you to remove TTY support which can save space, and |
| blocks features that require TTY from inclusion in the kernel. |
| TTY is required for any text terminals or serial port |
| communication. Most users should leave this enabled. |
| |
| if TTY |
| |
| config VT |
| bool "Virtual terminal" if EXPERT |
| select INPUT |
| default y if !UML |
| help |
| 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-<function key>. |
| |
| 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 :-) |
| |
| config CONSOLE_TRANSLATIONS |
| depends on VT |
| default y |
| bool "Enable character translations in console" if EXPERT |
| help |
| This enables support for font mapping and Unicode translation |
| on virtual consoles. |
| |
| config VT_CONSOLE |
| bool "Support for console on virtual terminal" if EXPERT |
| depends on VT |
| default y |
| help |
| 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. |
| |
| config VT_CONSOLE_SLEEP |
| def_bool y |
| depends on VT_CONSOLE && PM_SLEEP |
| |
| config HW_CONSOLE |
| bool |
| depends on VT |
| default y |
| |
| config VT_HW_CONSOLE_BINDING |
| bool "Support for binding and unbinding console drivers" |
| depends on HW_CONSOLE |
| help |
| The virtual terminal is the device that interacts with the physical |
| terminal through console drivers. On these systems, at least one |
| console driver is loaded. In other configurations, additional console |
| drivers may be enabled, such as the framebuffer console. If more than |
| 1 console driver is enabled, setting this to 'y' will allow you to |
| select the console driver that will serve as the backend for the |
| virtual terminals. |
| |
| See <file:Documentation/driver-api/console.rst> for more |
| information. For framebuffer console users, please refer to |
| <file:Documentation/fb/fbcon.rst>. |
| |
| config UNIX98_PTYS |
| bool "Unix98 PTY support" if EXPERT |
| default y |
| help |
| 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/<number>. 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. |
| |
| config LEGACY_PTYS |
| bool "Legacy (BSD) PTY support" |
| default y |
| help |
| 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. |
| |
| config LEGACY_PTY_COUNT |
| int "Maximum number of legacy PTY in use" |
| depends on LEGACY_PTYS |
| range 0 256 |
| default "256" |
| help |
| 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. |
| |
| config LEGACY_TIOCSTI |
| bool "Allow legacy TIOCSTI usage" |
| default y |
| help |
| Historically the kernel has allowed TIOCSTI, which will push |
| characters into a controlling TTY. This continues to be used |
| as a malicious privilege escalation mechanism, and provides no |
| meaningful real-world utility any more. Its use is considered |
| a dangerous legacy operation, and can be disabled on most |
| systems. |
| |
| Say 'Y here only if you have confirmed that your system's |
| userspace depends on this functionality to continue operating |
| normally. |
| |
| This functionality can be changed at runtime with the |
| dev.tty.legacy_tiocsti sysctl. This configuration option sets |
| the default value of the sysctl. |
| |
| config LDISC_AUTOLOAD |
| bool "Automatically load TTY Line Disciplines" |
| default y |
| help |
| Historically the kernel has always automatically loaded any |
| line discipline that is in a kernel module when a user asks |
| for it to be loaded with the TIOCSETD ioctl, or through other |
| means. This is not always the best thing to do on systems |
| where you know you will not be using some of the more |
| "ancient" line disciplines, so prevent the kernel from doing |
| this unless the request is coming from a process with the |
| CAP_SYS_MODULE permissions. |
| |
| Say 'Y' here if you trust your userspace users to do the right |
| thing, or if you have only provided the line disciplines that |
| you know you will be using, or if you wish to continue to use |
| the traditional method of on-demand loading of these modules |
| by any user. |
| |
| This functionality can be changed at runtime with the |
| dev.tty.ldisc_autoload sysctl, this configuration option will |
| only set the default value of this functionality. |
| |
| source "drivers/tty/serial/Kconfig" |
| |
| config SERIAL_NONSTANDARD |
| bool "Non-standard serial port support" |
| depends on HAS_IOMEM |
| help |
| 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 |
| 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. |
| |
| config MOXA_INTELLIO |
| tristate "Moxa Intellio support" |
| depends on SERIAL_NONSTANDARD && (ISA || EISA || PCI) |
| select FW_LOADER |
| help |
| 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. |
| |
| config MOXA_SMARTIO |
| tristate "Moxa SmartIO support v. 2.0" |
| depends on SERIAL_NONSTANDARD && PCI |
| help |
| Say Y here if you have a Moxa SmartIO multiport serial card and/or |
| want to help develop a new version of this driver. |
| |
| This is upgraded (1.9.1) driver from original Moxa drivers with |
| changes finally resulting in PCI probing. |
| |
| This driver can also be built as a module. The module will be called |
| mxser. If you want to do that, say M here. |
| |
| config SYNCLINK_GT |
| tristate "SyncLink GT/AC support" |
| depends on SERIAL_NONSTANDARD && PCI |
| help |
| Support for SyncLink GT and SyncLink AC families of |
| synchronous and asynchronous serial adapters |
| manufactured by Microgate Systems, Ltd. (www.microgate.com) |
| |
| config N_HDLC |
| tristate "HDLC line discipline support" |
| depends on SERIAL_NONSTANDARD |
| help |
| Allows synchronous HDLC communications with tty device drivers that |
| support synchronous HDLC such as the Microgate SyncLink adapter. |
| |
| This driver can 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. |
| |
| config PPC_EPAPR_HV_BYTECHAN |
| bool "ePAPR hypervisor byte channel driver" |
| depends on PPC |
| select EPAPR_PARAVIRT |
| help |
| This driver creates /dev entries for each ePAPR hypervisor byte |
| channel, thereby allowing applications to communicate with byte |
| channels as if they were serial ports. |
| |
| config PPC_EARLY_DEBUG_EHV_BC |
| bool "Early console (udbg) support for ePAPR hypervisors" |
| depends on PPC_EPAPR_HV_BYTECHAN=y |
| help |
| Select this option to enable early console (a.k.a. "udbg") support |
| via an ePAPR byte channel. You also need to choose the byte channel |
| handle below. |
| |
| config PPC_EARLY_DEBUG_EHV_BC_HANDLE |
| int "Byte channel handle for early console (udbg)" |
| depends on PPC_EARLY_DEBUG_EHV_BC |
| default 0 |
| help |
| If you want early console (udbg) output through a byte channel, |
| specify the handle of the byte channel to use. |
| |
| For this to work, the byte channel driver must be compiled |
| in-kernel, not as a module. |
| |
| Note that only one early console driver can be enabled, so don't |
| enable any others if you enable this one. |
| |
| If the number you specify is not a valid byte channel handle, then |
| there simply will be no early console output. This is true also |
| if you don't boot under a hypervisor at all. |
| |
| config GOLDFISH_TTY |
| tristate "Goldfish TTY Driver" |
| depends on GOLDFISH |
| select SERIAL_CORE |
| select SERIAL_CORE_CONSOLE |
| help |
| Console and system TTY driver for the Goldfish virtual platform. |
| |
| config GOLDFISH_TTY_EARLY_CONSOLE |
| bool |
| default y if GOLDFISH_TTY=y |
| select SERIAL_EARLYCON |
| |
| config N_GSM |
| tristate "GSM MUX line discipline support (EXPERIMENTAL)" |
| depends on NET |
| help |
| This line discipline provides support for the GSM MUX protocol and |
| presents the mux as a set of 61 individual tty devices. |
| |
| config NOZOMI |
| tristate "HSDPA Broadband Wireless Data Card - Globe Trotter" |
| depends on PCI |
| help |
| If you have a HSDPA driver Broadband Wireless Data Card - |
| Globe Trotter PCMCIA card, say Y here. |
| |
| To compile this driver as a module, choose M here, the module |
| will be called nozomi. |
| |
| config MIPS_EJTAG_FDC_TTY |
| bool "MIPS EJTAG Fast Debug Channel TTY" |
| depends on MIPS_CDMM |
| help |
| This enables a TTY and console on the MIPS EJTAG Fast Debug Channels, |
| if they are present. This can be useful when working with an EJTAG |
| probe which supports it, to get console output and a login prompt via |
| EJTAG without needing to connect a serial cable. |
| |
| TTY devices are named e.g. ttyFDC3c2 (for FDC channel 2 of the FDC on |
| CPU3). |
| |
| The console can be enabled with console=fdc1 (for FDC channel 1 on all |
| CPUs). Do not use the console unless there is a debug probe attached |
| to drain the FDC TX FIFO. |
| |
| If unsure, say N. |
| |
| config MIPS_EJTAG_FDC_EARLYCON |
| bool "Early FDC console" |
| depends on MIPS_EJTAG_FDC_TTY |
| help |
| This registers a console on FDC channel 1 very early during boot (from |
| MIPS arch code). This is useful for bring-up and debugging early boot |
| issues. |
| |
| Do not enable unless there is a debug probe attached to drain the FDC |
| TX FIFO. |
| |
| If unsure, say N. |
| |
| config MIPS_EJTAG_FDC_KGDB |
| bool "Use KGDB over an FDC channel" |
| depends on MIPS_EJTAG_FDC_TTY && KGDB |
| default y |
| help |
| This enables the use of KGDB over an FDC channel, allowing KGDB to be |
| used remotely or when a serial port isn't available. |
| |
| config MIPS_EJTAG_FDC_KGDB_CHAN |
| int "KGDB FDC channel" |
| depends on MIPS_EJTAG_FDC_KGDB |
| range 2 15 |
| default 3 |
| help |
| FDC channel number to use for KGDB. |
| |
| config NULL_TTY |
| tristate "NULL TTY driver" |
| help |
| Say Y here if you want a NULL TTY which simply discards messages. |
| |
| This is useful to allow userspace applications which expect a console |
| device to work without modifications even when no console is |
| available or desired. |
| |
| In order to use this driver, you should redirect the console to this |
| TTY, or boot the kernel with console=ttynull. |
| |
| If unsure, say N. |
| |
| config VCC |
| tristate "Sun Virtual Console Concentrator" |
| depends on SUN_LDOMS |
| help |
| Support for Sun logical domain consoles. |
| |
| source "drivers/tty/hvc/Kconfig" |
| |
| config RPMSG_TTY |
| tristate "RPMSG tty driver" |
| depends on RPMSG |
| help |
| Say y here to export rpmsg endpoints as tty devices, usually found |
| in /dev/ttyRPMSGx. |
| This makes it possible for user-space programs to send and receive |
| rpmsg messages as a standard tty protocol. |
| |
| To compile this driver as a module, choose M here: the module will be |
| called rpmsg_tty. |
| |
| endif # TTY |
| |
| source "drivers/tty/serdev/Kconfig" |
