[lkml]   [2006]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: 8250 serial console fixes -- issue

    Hi Alan,

    The serial console driver has a host of issues

    - end of line should be CR LF, not LF CR

    - 'r' option for CTS/RTS flow control assumes CTS is
    asserted when DSR is not asserted. This is wrong as
    lots of modems float control lines when off. No
    control signals are defined is DSR is unasserted.

    - [SECURITY] 'r' should require DCD to be asserted
    before outputing characters. Otherwise we talk to
    Hayes modem command mode. This allows a non-root
    user to re-program the modem and is a major security
    issue is people configure calling line identification
    or encryption to restrict use of the serial console.

    - 'r' option has insanely slow CTS timeout. So if a
    terminal server is inactive the kernel can take
    30 minutes to boot as each character write to the
    serial console requires a CTS timeout.

    All of these have been reported to me multiple times
    (I'm maintainer of the Remote-Serial-Console-HOWTO).

    I occassionally clean up and repost a patch I wrote years
    ago which never gets integrated (although it ships in the
    patchset of a number of kernels from supercomputer vendors).
    I'm happy to clean it up again if there's a hope of

    for the most recent attempt.

    Thanks so much,

    Glen Turner Tel: (08) 8303 3936 or +61 8 8303 3936
    Australia's Academic & Research Network
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2006-02-03 03:04    [W:0.035 / U:4.848 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site