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Re: Using serial port

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  • pizzulicchio1981
    ... of the ... with the ... terminal.. for ... boot? ... (redboot). ... display the ... Unslung ... point, an ... firmware ... to the ... The Linux ... the log
    Message 1 of 3 , Jan 10, 2008
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      --- In nslu2-linux@yahoogroups.com, "Mike \(mwester\)" <mwester@...>
      wrote:
      >
      > "pizzulicchio1981" <pizzulicchio@...> writes:
      >
      > > I'm interesting to know if it's possible to view the boot strap
      of the
      > > NSLU using the serial port.
      >
      > Yes, that is it's primary purpose. It is also possible to interact
      with the
      > bootloader on the NSLU2.
      >
      > > Simply....
      > >
      > > The serial port gives a continuos output ( as a classic
      terminal.. for
      > > example a cisco router - modem - switch ) or it startups during
      boot?
      >
      > At initial power-up, the serial port is used by the bootloader
      (redboot).
      > As soon as the kernel begins to boot, the serial port is used to
      display the
      > boot log. What happens after that depends on the firmware -- With
      Unslung
      > (and the native Linksys firmware), once boot-up reaches a certain
      point, an
      > interactive shell is started on that port; with standard Linux
      firmware
      > (SlugOS) a login prompt appears and one must login to gain access
      to the
      > shell.
      >
      > > What are the beneficts of a serial port?
      >
      > Diagnostics, particularly early-boot-time failures and debugging.
      The Linux
      > kernel attempts to do its best to log all events and messages to
      the log
      > files, as specified by the user. However, messages and events that
      occur
      > before such logging can be set up are lost without a serial
      console. Also,
      > in the event of the failure of the storage device to which the logs
      are
      > routed, again the serial port is the only place one can see the
      actual
      > event.
      >
      > [I should note that Unslung 6.10 includes an implementation
      of "netconsole",
      > which attempts to address some (but not all) of these issues. Of
      course,
      > netconsole has been available for SlugOS for some time now. In a
      nutshell,
      > what netconsole does is take console messages and transmit them on
      the
      > ethernet port. Even so, netconsole requires that your NSLU2 boot
      up to the
      > point where it can function on the network, so it is still very
      beneficial
      > to have a serial port for diagnosing early-boot issues. In other
      words:
      > netconsole is better than nothing, but a serial console on the
      NSLU2 is
      > still ideal.]
      >
      > Mike (mwester)
      >


      I'm Using Debian! What appens during boot strap ? ( this NSLU is
      fantastic !!! )
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