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  1. #1

    custom tty driver problems with mgetty


    I'm new to linux, so please point out anything obvious that I'm doing wrong.

    I'm trying to develop a tty driver for an embedded system. The purpose is to allow terminal login through a low speed modem. I'm using mgetty for this. I've deveopled the tty driver following the rcommendations in the O'Reilly Linux Device Drivers book. The tty driver seems to work well, and mgetty initializes the modem, answers rings, and gets a username. From the mgetty source, I can see that it then passes control to login.

    Login never seems to repsond to any input from the tty driver. It will evauntally display a login timeout message and mgetty will respawn. I've redirected the line discipline read functions to duplicate functions in my tty driver so I could add logging statements to find out what was wrong. From what I can tell, it looks as if there is never another read attempt after login is called. I get write data from login, but never a read request.

    Obviously login is functional as I've logged into system with a external modem connected to a serial port, so the problem must be somewhere in my tty driver.

    Any helpful suggestions as to where I should look next would be appreciated.


  2. #2
    Maybe do some manual testing of it, connect to your tty attached device using something like HyperTerminal on windows or Minicom on linux and try sending the information that login would send - essentially, emulating what the login program should be doing - that may make it easier to find the source of the problem?

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