How to boot directly into linux on an OldWorld Mac

[Mike Kimmick]

I am an owner of an OldWorld mac (7600), and I thought I'd share some info 
with the PPC linux community starting with YDL users.  Since my mac is an 
oldworld mac, I have read nothing but the fact that I have to use BootX to 
boot into linux.  However, a couple of years ago when LinuxPPC 2000 Q4 was 
out, this CD was bootable in my machine, and it booted directly into the 
linux installer.  So after digging through the newsgroups and not finding 
any specific info regarding the boot method/software on the LinuxPPC 2000 Q4 
CD, I remembered I had burned my own copy of this CD.  The answer to the 
boot method was right there in the README in the System Folder on the 
CD...and this method still applies today.  Here's the README:

****************************************************************
LinuxPPC System Folder README

This software was written by Benjamin Herrenschmidt <bh40@calva.net> & Jeff 
Carr <jcarr@linuxppc.org>

This is the LinuxPPC System Folder.

It is composed of miboot (the System file), yaboot (the MacOS ROM image), 
and a empty Finder file (which makes the Mac OS think it's a real System 
Folder). There is also a yaboot.conf file. You can edit this file to set the 
Linux boot preferences.

Documentation for editing the yaboot.conf file is at  
<http://linuxppc.org/documentation/yaboot/>.
****************************************************************

So, to test this, I created a new Mac Standard partition (47MB), named this 
drive "YDL Boot",  and did the following.

1. Created two folders on "YDL Boot": "System Folder" and "Linux Kernels"

2. Copied boot.msg from the "boot" folder of YDL CD 1 to the root of "YDL 
Boot".

3. Copied ramdisk.image.gz from the "images" folder of YDL CD1 to the root 
of "YDL Boot".

4. Copied both kernels, vmlinux-2.4.20.8d and vmlinux-2.4.20-8dBOOT, from 
the "boot" folder of YDL CD1 to the "Linux Kernels" folder on "YDL Boot".

5. Copied "yaboot" and yaboot.conf from the "boot" folder of YDL CD1 to 
the "System Folder" on "YDL Boot".

6. Mounted miboot.img (part of the BootX 1.2.2.sit), and copied Finder and 
System to the "System Folder" on "YDL Boot"

7. Lastly, I had to edit the yaboot.conf file accordingly...see below.

Here is my yaboot.conf file

message=boot.msg
timeout=120
default=install

image = vmlinux-2.4.20-8dBOOT
  label = install
  initrd = ramdisk.image.gz
  initrd-size = 8192

image = vmlinux-2.4.20-8dBOOT
  label = install-safe
  initrd = ramdisk.image.gz
  initrd-size = 8192
  append="text"
  novideo

image = vmlinux-2.4.20-8d
  label = linux

image = vmlinux.2.4.20-8d
  label = linux-safe
  novideo

With this configuration in place, I selected "YDL Boot" as the startup drive 
from MacOS's Startup Disk control panel.  After rebooting, I found that the 
machine was booting directly into linux.

Now, I can't say this works on all OldWorld macs, since I only have one of 
many flavors. And, I've noticed that occasionally, from MacOS 9, the "YDL 
Boot" drive is mysteriously not recognized as having a valid system folder.  
I just move both the Finder and System files out of the System Folder and 
put them back in to fix this problem.  Of course, when I have the "YDL Boot" 
drive selected as the startup drive and I want to boot directly into MacOS, 
I have to hold down Apple-Option-Shift-Delete to boot from my MacOS drive.

One last note.  I have a G3 Upgrade card and as of yet, I don't know how to 
set the G3 Cache settings in linux.  Using BootX this can be done easily, 
but I need a way to either pass kernel arguments (and I don't know what 
those arguments might be) via yaboot, or figure out how to set cache 
settings in linux.


Mike Kimmick

--
Open WebMail Project (http://openwebmail.org)