I've used UDP packets on other projects using NetCat (nc -u) http://netcat.sourceforge.net/ to give me an interactive console over UDP. This works really well for command/response type interaction. It works less well on console messages type interactions when the embedded system is spontaneously sending print messages.
Since UDP is connectionless, you need to determine when and to whom to send print messages. As I see it, there are a couple of options:
1) Use an environment variable to set the IP address and the port of the destination. If the env var doesn't exist or is set to 0, suppress the UDP packets. Note that this would allow the destination to be the broadcast IP address which would be good for capturing packets, and especially usefull for using a host to log them, but bad if you have lots of embedded systems all spewing lots of messages. It would also allow the embedded system to target a given host.
2) If the embedded system receives a packet on the console UDP port, send all console packets back to the sender. This would allow the interaction to be triggered by an arbitrary host, but would require that host to knock on the door of the embedded system first (not good for initial power up messages).
My preference would be #1.
gvb
-----Original Message----- From: u-boot-users-admin@lists.sourceforge.net [mailto:u-boot-users-admin@lists.sourceforge.net]On Behalf Of Laurent Mohin Sent: Tuesday, February 24, 2004 11:42 AM To: Wolfgang Denk Cc: u-boot-users@lists.sourceforge.net Subject: Re: [U-Boot-Users] telnet server on u-boot
Wolfgang,
In message above, you wrote :
For some remote instruments, I need to be able to have a
telnet access to
the boot in case of my Linux kernel and file system are
down (after an
upgrade for example). I don't think that u-boot provide telnet support and I
had a look at
another boot project called redboot that provide such a
functionality.
I have a couple of questions : Does anybody see another solution than telnet to control a remote instrument?
There are many solutions. You don't provide much
informatiuon about
your workign environment so it is difficult to make a good
recommen-
dation. Standard solutions include: use a modem to
attach to the
serial console; use a terminal server to attach to
the serial
console; etc.
Use of a modem or a terminal server to attach to the serial console is not a good solution for me, because I hope to deploy at least several hundred of instruments. And the only link I have with them is thru Ethernet. That's why I'm looking for something similar as telnet.
Thanks for your reply,
Laurent
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