Line-Discipline Module

In the pseudo-TTY subsystem, the line discipline module is pushed on the slave side to present the user with the terminal interface.

ldterm(7M) can turn off the processing of the c_iflag, c_oflag, and c_lflag fields to allow processing to take place elsewhere. The ldterm(7M) module can also turn off all canonical processing when it receives an M_CTL message with the MC_NO_CANON command to support remote mode. Although ldterm(7M) passes through messages without processing them, the appropriate flags are set when a ioctl(2), such as TCGETA or TCGETS, is issued to indicate that canonical processing is being performed.

Figure 14-2 Pseudo-TTY Subsystem Architecture