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Date:      Tue, 4 Feb 2003 00:21:36 +0000 (GMT)
From:      Andrew Gordon <arg-bsd@arg1.demon.co.uk>
To:        Lucky Green <shamrock@cypherpunks.to>
Cc:        <freebsd-current@FreeBSD.ORG>
Subject:   RE: L440gx+ serial BIOS needs text mode
Message-ID:  <20030204000002.P42367-100000@server.arg.sj.co.uk>
In-Reply-To: <002f01c2cbc0$22a2d010$6601a8c0@VAIO650>

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On Mon, 3 Feb 2003, Lucky Green wrote:
>
> However, the Intel L440gx+ motherboard I have (it came in a VA Linux
> rackmount) seems to have a separate CPU performing all kinds of
> monitoring tasks, watchdog, etc, so I was hoping this separate CPU was
> actually performing the serial console task. As I read it on page 64 of
> the manual (download from Intel), the second serial port is actually
> connected through a multiplexer to the Baseboard Management Controller
> (Dallas 82CH10) in my configuration.
> ftp://download.intel.com/support/motherboards/server/l440gx/254151-003.p
> df

I've used several generations of these intel boards, though not the exact
one which you have, most recently the se7500wv2.

All of them are more conventional than it might appear:

 - The 'screen scraper' for serial access to the BIOS works from
   software on the main (i386) CPU.   The earlier machines didn't
   have on-board video, so mapped in some ordinary RAM to the video
   area if you ran them without a video card fitted; later machines
   have video hardware and the console redirection polls this RAM.
   Either way, it's BIOS software generating ANSI escapes out of
   the ordinary serial port, and this stops when the OS boots.

 - The management CPU sits between the external serial port connector
   and the UART in the main CPU's chipset.  Hence the OS running
   on the main CPU always thinks it's got a standard COM port, it's
   just a question of whether data sent to/from that port makes it
   to the external connector or gets subverted by the management CPU.

 - On the latest machines featuring 'serial over LAN', you can
   persuade the management CPU to subvert the serial port and
   pass the data over one of the ethernet ports.  This seems to use
   a proprietary protocol, but if you have one Windows machine
   somewhere with the Intel management software loaded on it, you
   can use that to proxy the protocol for any number of managed
   machines - ie. telnet to port 623 on the Windows machine, then
   connect back to the target machine and get attached to the
   serial console (and so get a FreeBSD login, if that's what is
   running on COM2).

 - Medium-aged machines seem to have all the hardware to subvert the
   serial and ethernet ports, but won't do serial redirection apart
   from controlling the BIOS.  Upgrading the BMC software didn't
   help on the machine I had in this category.

Disclaimer: the above is just from playing with the machines and reading
the documentaton, so I may be wrong.


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