"Spy'ing" characters sent thru serial port ?

From: Paul Rolland (rol_at_as2917.net)
Date: 07/06/05

  • Next message: randy_dunlap: "Re: bios interaction with linux kernel after uncompression."
    To: <linux-kernel@vger.kernel.org>
    Date:	Wed, 6 Jul 2005 17:06:30 +0200
    
    

    Hello,

    We have a machine connected to a modem using the serial port, and from
    time to time, the modem complains the machine sent him a full 2K buffer
    (in fact, 2047 bytes) which were already sent.

    We've been investigating at the application level, using strace to
    monitor what is sent to the serial port, and at no time such a buffer is
    sent.

    This problem is occuring on a random basis, and attempts to reproduce
    it in a test environment failed to date.

    Is it possible to '(log|copy|...)' the chars that are sent on the
    serial port to some other place (without altering too much the performance
    of the machine, we are running the port a 9600bps), at the lowest level ?

    Or is there a known issue of the serial port (or tty) buffer being
    resent on the line in some weird conditions ? Any change done on
    ->head and ->tail handling that could fix that ?

    This problem is with Linux 2.4.27 (I know 2.4.31 is out, but nothing
    related to that is present in the Changelog)

    Regards,
    Paul

    Paul Rolland, rol(at)as2917.net
    ex-AS2917 Network administrator and Peering Coordinator

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  • Next message: randy_dunlap: "Re: bios interaction with linux kernel after uncompression."

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