Kconfig 6.2 KB

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  1. config VT
  2. bool "Virtual terminal" if EXPERT
  3. depends on !S390
  4. select INPUT
  5. default y
  6. ---help---
  7. If you say Y here, you will get support for terminal devices with
  8. display and keyboard devices. These are called "virtual" because you
  9. can run several virtual terminals (also called virtual consoles) on
  10. one physical terminal. This is rather useful, for example one
  11. virtual terminal can collect system messages and warnings, another
  12. one can be used for a text-mode user session, and a third could run
  13. an X session, all in parallel. Switching between virtual terminals
  14. is done with certain key combinations, usually Alt-<function key>.
  15. The setterm command ("man setterm") can be used to change the
  16. properties (such as colors or beeping) of a virtual terminal. The
  17. man page console_codes(4) ("man console_codes") contains the special
  18. character sequences that can be used to change those properties
  19. directly. The fonts used on virtual terminals can be changed with
  20. the setfont ("man setfont") command and the key bindings are defined
  21. with the loadkeys ("man loadkeys") command.
  22. You need at least one virtual terminal device in order to make use
  23. of your keyboard and monitor. Therefore, only people configuring an
  24. embedded system would want to say N here in order to save some
  25. memory; the only way to log into such a system is then via a serial
  26. or network connection.
  27. If unsure, say Y, or else you won't be able to do much with your new
  28. shiny Linux system :-)
  29. config CONSOLE_TRANSLATIONS
  30. depends on VT
  31. default y
  32. bool "Enable character translations in console" if EXPERT
  33. ---help---
  34. This enables support for font mapping and Unicode translation
  35. on virtual consoles.
  36. config VT_CONSOLE
  37. bool "Support for console on virtual terminal" if EXPERT
  38. depends on VT
  39. default y
  40. ---help---
  41. The system console is the device which receives all kernel messages
  42. and warnings and which allows logins in single user mode. If you
  43. answer Y here, a virtual terminal (the device used to interact with
  44. a physical terminal) can be used as system console. This is the most
  45. common mode of operations, so you should say Y here unless you want
  46. the kernel messages be output only to a serial port (in which case
  47. you should say Y to "Console on serial port", below).
  48. If you do say Y here, by default the currently visible virtual
  49. terminal (/dev/tty0) will be used as system console. You can change
  50. that with a kernel command line option such as "console=tty3" which
  51. would use the third virtual terminal as system console. (Try "man
  52. bootparam" or see the documentation of your boot loader (lilo or
  53. loadlin) about how to pass options to the kernel at boot time.)
  54. If unsure, say Y.
  55. config HW_CONSOLE
  56. bool
  57. depends on VT && !S390 && !UML
  58. default y
  59. config VT_HW_CONSOLE_BINDING
  60. bool "Support for binding and unbinding console drivers"
  61. depends on HW_CONSOLE
  62. default n
  63. ---help---
  64. The virtual terminal is the device that interacts with the physical
  65. terminal through console drivers. On these systems, at least one
  66. console driver is loaded. In other configurations, additional console
  67. drivers may be enabled, such as the framebuffer console. If more than
  68. 1 console driver is enabled, setting this to 'y' will allow you to
  69. select the console driver that will serve as the backend for the
  70. virtual terminals.
  71. See <file:Documentation/console/console.txt> for more
  72. information. For framebuffer console users, please refer to
  73. <file:Documentation/fb/fbcon.txt>.
  74. config UNIX98_PTYS
  75. bool "Unix98 PTY support" if EXPERT
  76. default y
  77. ---help---
  78. A pseudo terminal (PTY) is a software device consisting of two
  79. halves: a master and a slave. The slave device behaves identical to
  80. a physical terminal; the master device is used by a process to
  81. read data from and write data to the slave, thereby emulating a
  82. terminal. Typical programs for the master side are telnet servers
  83. and xterms.
  84. Linux has traditionally used the BSD-like names /dev/ptyxx for
  85. masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
  86. has a number of problems. The GNU C library glibc 2.1 and later,
  87. however, supports the Unix98 naming standard: in order to acquire a
  88. pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
  89. terminal is then made available to the process and the pseudo
  90. terminal slave can be accessed as /dev/pts/<number>. What was
  91. traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
  92. All modern Linux systems use the Unix98 ptys. Say Y unless
  93. you're on an embedded system and want to conserve memory.
  94. config DEVPTS_MULTIPLE_INSTANCES
  95. bool "Support multiple instances of devpts"
  96. depends on UNIX98_PTYS
  97. default n
  98. ---help---
  99. Enable support for multiple instances of devpts filesystem.
  100. If you want to have isolated PTY namespaces (eg: in containers),
  101. say Y here. Otherwise, say N. If enabled, each mount of devpts
  102. filesystem with the '-o newinstance' option will create an
  103. independent PTY namespace.
  104. config LEGACY_PTYS
  105. bool "Legacy (BSD) PTY support"
  106. default y
  107. ---help---
  108. A pseudo terminal (PTY) is a software device consisting of two
  109. halves: a master and a slave. The slave device behaves identical to
  110. a physical terminal; the master device is used by a process to
  111. read data from and write data to the slave, thereby emulating a
  112. terminal. Typical programs for the master side are telnet servers
  113. and xterms.
  114. Linux has traditionally used the BSD-like names /dev/ptyxx
  115. for masters and /dev/ttyxx for slaves of pseudo
  116. terminals. This scheme has a number of problems, including
  117. security. This option enables these legacy devices; on most
  118. systems, it is safe to say N.
  119. config LEGACY_PTY_COUNT
  120. int "Maximum number of legacy PTY in use"
  121. depends on LEGACY_PTYS
  122. range 0 256
  123. default "256"
  124. ---help---
  125. The maximum number of legacy PTYs that can be used at any one time.
  126. The default is 256, and should be more than enough. Embedded
  127. systems may want to reduce this to save memory.
  128. When not in use, each legacy PTY occupies 12 bytes on 32-bit
  129. architectures and 24 bytes on 64-bit architectures.