Boot chooser for PowerPC Macs

Like Yaboot, allows choosing Mac OS 9, Mac OS X and Linux (and probably also other OSes).

Improvements over Yaboot's chooser:

• Every OS can have its own keyboard shortcut.
• If you need time to think, just hit any other key to stop the timeout counter.
• You can have as many installs of any kind as you want. For example, multiple OS X partitions, or multiple Linux distros.
• Uses a simple config file. Yaboot uses one complex file for both first-stage "choosing an OS" and second-stage "choosing a kernel".
• Allows USB boot.
• Can be configured and installed from either OS X or Linux.
• Falls back to other options if the default is not available, eg: if it's on a damaged partition or an external disk.

To use ofchooser, you need to first write a config file, then build and install a boot script, and finally trigger the boot script.

To use ofchooser, you'll need a small configuration file. This is just a text file, using "#" to start comments. Each line is one of:

• A loader: k "My loader" hd:9,yaboot configures a second-stage bootloader named "My loader", with the keyboard shortcut "k".
  • If the name has no spaces, it does not have to be quoted.
  • The path to the file being loaded must be an Open Firmware path.
  • Optionally, a loader line can have at the end a comma-separated list of loader options, eg: probe-usb.
• A default selection: default k makes the loader with the shortcut "k" the default if the timeout passes. If no default is specified, the first loader will be used.
• A timeout duration: timeout 5 sets a five-second timeout, before the default loader is chosen. The default timeout is 10 seconds.

Loader options:

• probe-usb: Before booting this loader, will probe USB ports. This is necessary to boot off USB on some models, but on other models can temporarily disable other USB devices like keyboards and mice.

If only a single loader is specified, ofchooser will skip the chooser interface, and just straight to that loader.

See the example configuration file.

Make sure you have Ruby installed. Any Ruby version since 1.8 should work, so even old OSes like Yellowdog Linux or Mac OS X 10.4 should be fine. You'll also need the ERB Ruby module, which is usually installed by default.

Run: ./ofchooser myconfig.cfg ofchooser.b

This will create a boot script "ofchooser.b", which you can then install.

There are two ways to install the boot script:

1. Just place it in an easy-to-remember place on an HFS or HFS+ partition. Eg on OS X: sudo cp ofchooser.b /.
2. If you have Yaboot installed, use the boot script as your "magicboot" file: sudo ybin -m ofchooser.b -v.
3. If you already have a partition of type "Apple_Bootstrap" for Grub or Yaboot, you can use Linux tools like mount and cp to place the boot script there.

Check which partition number your boot script is installed on.

Then on reboot, hold down Command-Option-O-F to enter Open Firmware. Use the boot command to trigger ofchooser. If it's on partition 9 of your internal hard disk: boot hd:9,ofchooser.b. You should now enter the chooser.

If you're happy with ofchooser, and want your computer to use it by default, set it as the boot device. Some ways to do this:

1. In Open Firmware: setenv boot-device=hd:9,ofchooser.b
2. In OS X: sudo nvram boot-device=hd:9,ofchooser.b
3. In modern Linux: sudo nvram --update-config boot-device=hd:9,ofchooser.b

Open Firmware paths look weird, so here's a tutorial

Each boot file's path looks like [device]:[partition],[path].

The device part can be a full Open Firmware device, which tends to look pretty complicated, eg: /pci@f2000000/usb@18/disk. In Open Firmware, you can list all full devices with dev / ls.

The device part can also be a short Open Firmware alias, such as hd for the internal hard drive. In Open Firmware, you can type devalias to see a list of all existing aliases, or nvalias myalias /full/ofpath to create a new custom alias.

The partition part is just a number indicating the partition on which the boot file lives. Note that Apple partitions often have unexpected numbers due to hidden partitions. Use blkid on Linux, or diskutil list on Mac OS X to see all your partitions and their actual numbers.

The path part is a directory-and-file path to the boot file. The path uses backslashes (\) as directory separators. You can omit the first separator, so a path in the root directory can be just ofchooser.b. Or a longer path could be ppc\grub\grub. There's also a special path \\:tbxi that chooses whatever boot file HFS/HFS+ considers "blessed", and is usually the easiest way to choose the Mac OS 9 or Mac OS X loader.

To make sure you have a path correct, you can use the dir command in Open Firmware. Eg: dir hd:9,\ will list the root directory of the given path.

Finally, as an extension, ofchooser treats the path "OF" as a special value, which exits from ofchooser back into Open Firmware.

• ofchooser is just a first-stage boot-chooser. You still need a second-stage bootloader like Yaboot or Grub to boot Linux.
• Only tested on a single iBook Dual USB.

ⓒ 2025 Dave Vasilevsky

Licensed under the GPL version 2 (or later), see COPYING.

Derived from Yaboot.