[syslinux] netconsole for pxelinux

[Luciano Miguel Ferreira Rocha]

On Fri, Mar 27, 2009 at 11:27:41AM +0100, Ferenc Wagner wrote:
> "H. Peter Anvin" <hpa at zytor.com> writes:
> 
> > Ferenc Wagner wrote:
> >
> >> I'm in the position that a network console would occasionally be very
> >> useful for me to control pxelinux.  Has the possibility of adding it
> >> (next to VGA and serial) been ever discussed?  I understand that it
> >> may sound somewhat contorted, but it could also serve instead of a
> >> TFTP PUT for extracting hardware info, for example...
> >>
> >> How hard would it be to add (considering gPXE as well)?
> >
> > If done over a UDP-based protocol, not very hard.
> 
> But what could provide the flow control?  xon/xoff?  Or could it be
> ignored, as it would mostly be needed in input direction only, and
> there's no point in pasting large amounts into the pxelinux console?
> 
> And would it need buffering, or just transfer one packet per character?

Depends on your requirements. On a local LAN, sending keystrokes and
receiving simple, small text, UDP should suffice, IMO.

> 
> > Keep in mind that Linux' netconsole protocol doesn't work -- it's
> > unidirectional only.
> 
> I didn't even know there was a "protocol" there, I always used simple
> (unidirectional) socat or netcat.  What do you mean?  Of course
> ideally it wouldn't need a specialised client either, if possible.

Linux netconsole is a kernel option for sending console messages (those
ending up in /dev/console and /var/log/messages, usually) to the
network.

Those messages are sent via UDP. See
Documentation/networking/netconsole.txt on the kernel sources.

About socat/netcat, those use the TCP/IP protocol, or, with -u, the
UDP/IP protocol.

-- 
lfr
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