Configuring a BEE2 for Linux


  1. Configuring a BEE2 for Linux
    1. Introduction
    2. Overview of Configuration
    3. Setting the Configuration Strings
    4. Boot Command String
    5. Changing Baud Rate


Introduction


The purpose of this page is to describe the steps required to setup a BEE2 board to properly boot linux. This is primarily concerned with setting up the EEPROM on the BEE2 to hold the proper configuration strings. You can also find information on building a BEE2 root filesystem on Compact Flash, building a root filesystem for NFS, and building a kernel.

Overview of Configuration


The BEE2 has a small 512 byte EEPROM which comes as part of the X1226 RTC. The EEPROM and RTC are connected to the IIC bus. We currently use a simple software IIC core which we developed to access the IIC and SMB devices on the board. We use the EEPROM to hold a series of key/value pairs which describe configuration information necessary to boot Linux. This information includes:

Setting the Configuration Strings


Our BEE2 test suite includes software to set and read the configuration strings for the board. We have information on building and running the test suite in the wiki. Once you have the test suite running on the board and are connected over the RS232 link, run the following command:

set_eeprom

This will prompt you to enter the four pieces of information mentioned above. For each item it will also print the old value which you can cut/paste with your terminal emulator if you don't want to change the value. When you are done entering each one, hit enter, and at the end it should pause for a few seconds while it writes the values to the EEPROM. To test that the values were written successfully run the command:

get_eeprom

Which should print out the values you just entered.

Boot Command String


The boot command is probably the most important value you will set. It is the string that is passed to the kernel on boot, and can take any of the acceptable boot parameters. Here is an example (and recommended) command line for the BEE2 Linux reference design:

console=tty0 console=ttyS0,115200 nfsroot=/b2roots/hostname ip=192.168.0.100:192.168.0.1:192.168.0.1:255.255.255.0:hostname:eth0:off mem=512M rw root=/dev/nfs

Changing Baud Rate


The default baud rate for Linux on the BEE2 is 115200. There really isn't a good reason to change this, but if you find a reason to, you must change several things. First, you need to change the command line stored in the EEPROM from console=ttyS0,115200 to console=ttyS0,YOURBAUD. Next, you need to change the baud rate parameter stored in the EEPROM to your baud rate. Finally, on your root file system you need to edit the file /etc/inittab and change the baud rate on the getty that spawns on ttyS0.

Bee2LinuxConfig (last edited 2006-07-13 18:43:23 by alschult)