config VT bool "Virtual terminal" if EXPERT depends on !S390 select INPUT default y ---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-. 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 HW_CONSOLE bool depends on VT && !S390 && !UML default y config VT_HW_CONSOLE_BINDING bool "Support for binding and unbinding console drivers" depends on HW_CONSOLE default n ---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 for more information. For framebuffer console users, please refer to . 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/. 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 DEVPTS_MULTIPLE_INSTANCES bool "Support multiple instances of devpts" depends on UNIX98_PTYS default n ---help--- Enable support for multiple instances of devpts filesystem. If you want to have isolated PTY namespaces (eg: in containers), say Y here. Otherwise, say N. If enabled, each mount of devpts filesystem with the '-o newinstance' option will create an independent PTY namespace. 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.