TTY — The Linux Kernel Documentation

TTY structures¶

There are several major TTY structures. Every TTY device in a system has a corresponding struct tty_port. These devices are maintained by a TTY driver which is struct tty_driver. This structure describes the driver but also contains a reference to operations which could be performed on the TTYs. It is struct tty_operations. Then, upon open, a struct tty_struct is allocated and lives until the final close. During this time, several callbacks from struct tty_operations are invoked by the TTY layer.

Every character received by the kernel (both from devices and users) is passed through a preselected TTY Line Discipline (in short ldisc; in C, struct tty_ldisc_ops). Its task is to transform characters as defined by a particular ldisc or by user too. The default one is n_tty, implementing echoes, signal handling, jobs control, special characters processing, and more. The transformed characters are passed further to user/device, depending on the source.

In-detail description of the named TTY structures is in separate documents:

• TTY Driver and TTY Operations
  • Allocation
  • Registration
  • TTY Driver Reference
  • TTY Operations Reference
• TTY Port
  • TTY Port Functions
  • TTY Port Reference
  • TTY Port Operations Reference
• TTY Struct
  • Initialization
  • Name
  • Reference counting
  • Install
  • Read & Write
  • Start & Stop
  • Wakeup
  • Hangup
  • Misc
  • TTY Struct Flags
  • TTY Struct Reference
• TTY Line Discipline
  • Registration
  • Other Functions
  • Line Discipline Operations Reference
  • Driver Access
  • TTY Flags
  • Locking
  • Internal Functions
• TTY Buffer
  • Flip Buffer Management
  • Other Functions
  • Buffer Locking
  • Internal Functions
• TTY IOCTL Helpers
• TTY Internals
  • Kopen
  • Exported Internal Functions
  • Internal Functions
• Console
  • Struct Console
  • Struct Consw
  • Console functions