U-Boot with DHCP
Das U-Boot includes a basic DHCP client that is pretty trivial to utilize. This allows you to get the board connected to the network quickly and dynamically so you can transfer files at high speeds or other such fun things.
Setup
If you don't have a DHCP server set up already, see the guide for setting up a DHCP server.
Once you have that step out of the way, you should connect to the board like normal with a serial terminal. If you need help with that, see the terminal programs guide.
DHCP command
The U-Boot DHCP command is pretty simple. It takes no arguments. Just run the dhcp command!
bfin> dhcp BOOTP broadcast 1 BOOTP broadcast 2 DHCP client bound to address 192.168.0.133
Here you can see the board asking twice for an IP address and finally the server gives it the IP 192.168.0.133. Now you are all set to communicate on the network like normal.
Since the dhcp command is non-interactive, it can of course be run automatically at boot followed by other commands.
Environment Variables
The DHCP command will setup some environment variables automatically for you according to the DHCP information given to the board. At a minimum, the following variables will be set automatically:
| Variable | Meaning |
|---|---|
| ipaddr | The IP address of the Blackfin board |
| netmask | The Network Mask for the Blackfin board |
| serverip | The IP address used when running a command that needs a server (like tftp) |
| gatewayip | The IP address for routing packets outside of the local network (as defined by the netmask) |
To view all the variables, simply use the print command.
bfin> print bootcmd=run dhcp_boot bootdelay=30 baudrate=57600 loads_echo=1 ipaddr=192.168.0.133 serverip=192.168.0.32 gatewayip=192.168.0.1 netmask=255.255.255.0 hostname=BF533 netdev=eth0 tftp_boot=tftp 0x1000000 linux;bootelf 0x1000000;echo dhcp_boot=dhcp;bootelf 0x1000000;echo serial_boot=loadb;bootelf 0x1000000;echo stdin=serial stdout=serial stderr=serial
