booting rtems over the network?

Ian Caddy ianc at
Wed Jun 12 01:46:48 UTC 2002

Hi Jack,

This sounds like your Linux server is fragmenting the packets it is 
sending to your target.

Use the following command to check that your MTU for the Ethernet port 
is set to 1500.


If the MTU is set to less than 1500, the stack on the linux box may be 
fragmenting the bootp response.


Ian Caddy

Jack Cawkwell wrote:

>Please can someone help with booting RTEMS (i386) across a network.
>I have setup bootp and tftp on a Linux server, and the debugging
>messages suggest that the bootp server part is working (appears to
>be doing something sensible). tftp is working from the same server.
>The ROM image is read from a floppy on the client, and was obtained
>from, choosing the correct version for
>the network card, and selecting the boot from floppy option.
>The client boots, tries various network modes, and when it finds a
>working one, broadcasts, and then the server responds,
>at the client:
>Searching for server (DHCP)...
>ALERT: got a fragmented packet reconfigure your server
>at the server:
>bootpd[30134]: bootptab mtime: Sun Jun  9 11:56:48 2002
>bootpd[30134]: request from Ethernet address 00:D0:09:F1:E3:C1
>bootpd[30134]: found (pablo)
>bootpd[30134]: bootfile="/tftpboot/picodemo8.nbi"
>bootpd[30134]: vendor magic field is
>bootpd[30134]: request message length=548
>bootpd[30134]: request has DHCP msglen=1500
>bootpd[30134]: extended reply, length=1500, options=1264
>bootpd[30134]: Received: DHCPDISCOVER
>bootpd[30134]: Sent: DHCPOFFER
>bootpd[30134]: sending reply (with RFC1048 options)
>bootpd[30134]: setarp - 00:D0:09:F1:E3:C1
>I conclude that the boot image is wrong. I have tried many
>combinations of arguments to mknbi both with an RTEMS boot
>image and with a linux image. I must have missed something
>as none of the images work. They all produce the same message,
>ALERT: got a fragmented packet reconfigure your server
>Any suggestions would be welcome.
>Thanks, Jack


ianc at
Microsol (Aust) Pty Ltd

Phone: (+61) 08 9473 6600
Fax:   (+61) 08 9473 6699 

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