Testing Open Firmware on OLPC

An OLPC Open Firmware image is available for internal testing. It boots from a USB storage device, so you don't have to reprogram the OLPC FLASH to try it out. Once OFW is running, it can then boot Linux from the same or another USB storage device.

It works on both A and B OPLC boards.

Supported Features

The following features and capabilities are fairly well tested.

Booting Linux from USB storage
PS/2 keyboard and mouse
USB keyboard
GX video output
Serial console
All standard Open Firmware interactive commands
Loading custom pre-boot mod scripts from USB storage

Partially Supported ...

These features are present in the build but need some work.

USB network devices (only AX8817x-based devices for now)
TCP/IPv4 - NFS, HTTP, HTTPD (core code is mature but needs a NIC)
Graphical boot menu (needs icon and colormap cleanup)

Coming Soon ...

The code for these features is written, but not included in this build because it needs more testing and polish.

NAND FLASH/JFFS2 (Mostly working, needs polish)
DCON (Mostly working, needs polish)
SPI FLASH programming (Needs support for the new parts)
CaFe NAND (Waiting for the FPGA to be fixed)
CaFe SD (Needs polish)
SPI FLASH programming (Needs support for the new parts)
Marvell wireless (Written but completely untested)
Non-volatile storage of configuration variables (I don't want to touch the FLASH or CMOS RAM in this version)

Completely Missing

Not yet written...

IPv6

Installing Open Firmware

Get ofw-061011-1916.tgz and extract it with


tar xfz ofw-061011-1916.tgz

The tarball contains a binary file ofw-<VERSION>.bzi and a text file ofwmods.fth .

Copy both to a USB FLASH key that contains an ext3 file system (i.e. an OLPB boot disk). E.g.:


$ mount /dev/sda1 /key
$ cp ofw-061011-1916.bzi /key/boot/ofw.bzi
$ cp ofwmods.fth /key/boot

Modify /key/boot/olpc-boot.sh to add the following lines before the /sbin/kbl-kexec line:


if [ -f /key/boot/ofw.bzi ] ; then
    /sbin/kbl-kexec /key/boot/ofw.bzi ""
fi

Running Open Firmware

Open Firmware can use either the GX video and a keyboard (USB or PS/2) or a serial console (115200,8,n,1). A serial console gives you much more flexibility for debugging (scroll, cut and paste, capture output), but keyboard/screen is fine for routine use. USB keyboard takes priority over PS/2, and if neither is present, serial is used.

Insert the USB key and turn on the power. LinuxBIOS should boot Open Firmware, which then gives you 6 seconds to type a key before auto-booting Linux.

If you interrupt the auto-boot by typing a key, you will get an 'ok' prompt.

Some Things You Can Do

Boot Linux with boot
List the device tree with show-devs
Go into a device node with, for example, dev /pci/isa/i8042/keyboard
List the node's properties .properties
List the node's methods (driver procedures) with words
Decompile a method with, for example, see open
Look at config variables with printenv
Change a config variable with, for example, setenv input-device com1
Modify the kernel arguments with editenv boot-file
Switch to the serial port with com1 io
Switch to the keyboard with keyboard input
Switch to the screen with screen output
Switch to both keyboard and screen with ks-io
Look at the USB disk contents with dir disk:\boot\
Look at a file with more disk:\boot\olpc-boot.sh
Try the graphical menu with menu (it needs work...)
Write, compile, and debug Forth programs
Serial-download Forth programs with dl (^D to end)
Run Forth programs from disk with, for example fload disk:\myfile.fth

The command line editor has full intra-line editing and history (arrow keys), and command completion (TAB). Emacs control keys also work.

You can make persistent changes by editing the file /boot/ofwmods.fth (on another system). That file is loaded just before auto-booting. You can use it to override the configuration variables that control Linux booting, fixup hardware settings, or whatever.

http://firmworks.com/QuickRef.html shows a lot more things you can do. It includes a Forth language reference.

Last edited: 2006-10-11