.\" Hey Emacs! This file is -*- nroff -*- source. .\" .TH YABOOT 8 "21 November 2001" "GNU/Linux PowerPC" "System Manager's Manual" .SH NAME .B yaboot \- PowerMac OpenFirmware boot loader .SH SYNOPSIS .B Yaboot is an OpenFirmware ELF executable that bootstraps the Linux kernel. .SH DESCRIPTION This manual page explains the \fByaboot\fR OpenFirmware boot loader. .B yaboot is \fInot\fR a Linux or MacOS executable file. Attempting to execute \fByaboot\fR from a Linux shell will only result in a Segmentation Fault. \fByaboot\fR is meant to be executed only by OpenFirmware. .B yaboot is executed from OpenFirmware in the following manner: .I boot hd:2,yaboot where \fIhd:\fR is the OpenFirmware path for the hard disk, and the \fI2\fR is the partition number \fByaboot\fR is located on. In this example, the hard disk path is actually an OpenFirmware alias which is present on all NewWorld PowerMacs. It usually points to the internal ATA hard disk. If you have a SCSI disk, then you might execute \fByaboot\fR with this command: .I boot /pci@80000000/pci-bridge@d/ADPT,2930CU@2/@1:2,yaboot This path will vary depending on what kind of SCSI host adapter you have. For a more detailed explanation of OpenFirmware's [disgusting] paths, see man \fBbootstrap\fR(8). On IBM hardware \fByaboot\fR is directly copied to the \fBbootstrap\fR(8) partition raw, without any filesystem. OpenFirmware will boot from a type 0x41 PReP Boot parition marked bootable, this must contain \fByaboot\fR. On IBM hardware the config file is read directly from the root filesystem. On PowerMac hardware it must be present on the \fBbootstrap\fR(8) partition but .BR ybin (8) will take care of that. Fortunately you do not normally have to execute \fByaboot\fR manually. If you have partitioned your disk with a \fBbootstrap\fR(8) partition and used \fBybin\fR(8) to install \fByaboot\fR then you will not have to execute \fByaboot\fR yourself. (If this does not work you can also set the \fIboot-device\fR variable in OpenFirmware to have it boot automatically, see man \fBbootstrap\fR(8).) Once \fByaboot\fR has been executed by OpenFirmware it will display a \fIboot:\fR prompt where you may enter a label for a kernel image defined in \fByaboot.conf\fR(5). If there is no kernel image defined in \fByaboot.conf\fR(5) you can still boot an arbitrary image by specifying its absolute OpenFirmware path, similar to the above commands for executing \fByaboot\fR itself. Simply omit the \fIboot\fR command and enter only the pathname. (See EXAMPLES below) When booting an image (either as a predefined label or absolute path) any arguments are passed to the image. For example: .I boot: linux root=/dev/hda3 which would pass the argument \fIroot=/dev/hda3\fR to the kernel. .B yaboot should preferably be installed on a dedicated \fBbootstrap\fR(8) partition (type Apple_Bootstrap for PowerMacs, type 0x41 PReP Boot for IBM hardware). This allows the partition to be modified in such a way that OpenFirmware will load \fByaboot\fR or a boot menu automatically with a default OF configuration. If \fByaboot\fR cannot be installed on a \fBbootstrap\fR(8) partition it can be installed on the root of a MacOS boot partition instead. \fByaboot\fR however should not be installed in a subdirectory of the MacOS filesystem as this is less reliable and more difficult to execute from OpenFirmware. See the \fBybin\fR(8) man page for more details on installing \fByaboot\fR (\fBybin\fR(8) is a utility for installing \fByaboot\fR with minimal difficulty). The \fByaboot.conf\fR(5) file must be next to the \fByaboot\fR executable on the \fBbootstrap\fR(8) partition. \fBybin\fR(8) will take care of this. OpenFirmware may be accessed by holding down the \fIcommand, option, o, f\fR keys immediately upon power-up. OpenFirmware's settings may be reset to default values by holding down the \fIcommand, option, p, r\fR keys while cold booting. If you have G4 hardware then your OpenFirmware may already have a graphical boot selector built in. This selector can be accessed by holding down the \fIoption\fR key when booting the machine. You should see a screen with buttons for each bootable partition. The current version (included with \fBybin\fR(8) 0.13) of ofboot includes a badge icon, the button with a penguin icon is your \fBbootstrap\fR(8) partition. Thanks to Nicholas Humfrey for creating the Badge icon. The \fBbootstrap\fR(8) partition need not and .B should not be mounted anywhere on your filesystem, especially not on top of /boot. \fBYaboot\fR is able to load the kernels from the ext2fs root partition so that is where they should be kept. .SH EXAMPLES boot \fByaboot\fR from internal ATA disk, partition 2: .I boot hd:2,yaboot boot \fByaboot\fR from partition 2 of a disk with SCSI ID 2 attached to a Adaptec 2930 SCSI Host adapter (this is on a rev1 blue G3, it may vary on other models): .I boot /pci@80000000/pci-bridge@d/ADPT,2930CU@2/@2:2,yaboot boot a kernel image located on partition number 3 of internal ATA disk (from \fByaboot's\fR \fIboot:\fR prompt): .I hd:3,/boot/vmlinux boot a kernel image located on partition 3 of SCSI disk ID 2 on a Adaptec 2930 Host adapter (from \fByaboot's\fR \fIboot:\fR prompt): .I /pci@80000000/pci-bridge@d/ADPT,2930CU@2/@2:3,/vmlinux .SH FILES .nf /etc/yaboot.conf \- boot loader configuration file .fi .SH BUGS OpenFirmware .SH AUTHORS This man page was written by Ethan Benson . .P .B yaboot was written by Benjamin Herrenschmidt . .SH REPORTING BUGS Bugs in \fByaboot\fR should be reported to Ethan Benson .SH SEE ALSO .BR bootstrap (8), .BR yaboot.conf (5), .BR ybin (8).