Booting a Mac with Yellow Dog Linux

Date: Tue, 8 Apr 2003 14:03:04 +0200
From: Alexander Holst <holst at fh-pforzheim dot de>
Subject: Re: miboot documentation? (really minimal BootX)

Hi everybody,

here's a mini HOWTO for booting/installing via miboot (sorry for the 
long post):

All my YDL boxes here are booted via miboot (exept for my ANS ;), so 
they don't have any Apple Software on them any more. Only step 1] and 
2] usually require some form of MacOS.

In my experience, miboot works very well for OldWorld machines, as well 
as for B/W G3s. It is customizable trough a conf file called 
"boot.conf, which must reside on the root level of the HFS (or HFS+) 
partition. My HFS partitions are usually between 20 and 30 MB, which is 
enough, as long as you are not experimenting with too many different 
kernels. If you only have one, known to work kernel, even as little as 
15 MB could be enough.

IMHO, HFS is recommended as you'll then be able to mount that partition 
under Linux and alter the boot.conf file, to reflect any changes like 
boot args and kernels. I usually use miboot for installation as well. 
All you have to do, is to copy the desired installer ramdisk to the 
root level of the HFS partition and specify it in the boot.conf file. I 
even did a graphical install on a PM8200 this way ;) In case you want 
to have a dual boot system, miboot serves well, as you will be able to 
choose the volume containing miboot as a startup disk - just make it 
the second (or more) partition on the drive, so holding down 
<CMD><ALT><P><R> will enable you to reset the PRAM and enable you to 
boot back into Mac OS, or doing it the good ole way, using two or more 
SCSI disks, holding down <CMD><ALT><SHIFT><Backspace><# of SCSI ID of 
BootDrive> will let you boot off your desired boot drive :)

My usual steps in performing an install through miboot consist of the 
following:

1]
Boot from a bootable CD containing any drive partitioning utilities to 
partition/initialize your disk. A MacOS 8.1 or higher install CD is 
recomended as you will be able to access any other stuff you will need 
through the network. Making 1 partition suffices completely: 1 HFS 
partition, rest empty (that will be used for Linux later). As with all 
the installs I have performed so far, all installers (YDL 2.0, 2.2 & 
2.3) allowed me to partion the remaining space on the drive during 
installation. Make one partition that will become the HFS boot 
partition for the machine. Again, HFS is considered to be used rather 
than HFS+, for reasons explained above. Partition size: 15MB for 
machines with only one usable kernel, more for experimenting (take into 
consideration that each kernel requires between 3 and 5MB).


2]
Copy all needed miboot stuff on the newly created HFS partition. I 
usually use the Systemfolder of an old LinuxPPC2000 Q4 CD, as it has 
proved to work flawlessly (if neccessary, I could provide that). Needed 
are the following components:

a] a "System Folder" on the root level that contains "Finder" and 
"System", the actual miboot software. Be sure to open this "System 
Folder" at least once under MacOS, so it gets blessed, aka the icon of 
the folder in the Finder will contain a "Happy Mac", otherwise you 
won't be able to choose it as a boot drive in the StartupDisk control 
panel later on.

b] a text file called boot.conf on the root level (this file can be in 
SimpleText format or Linux format - I usually create it with SimpleText 
the first time, then edit it with gEdit, pico ... when installation has 
finished). Mine looks as follows:

init-message = "\nWelcome to YDL!\Press <TAB> for boot options.\n\n"
timeout = 50

default = bootYDL

image = vmlinux-2.4.18-0.8a
label = bootYDL
root = /dev/sdb8
append = "video=atyfb:vmode:18,cmode:24"

image = vmlinux-2.4YDLinstall
label = install_YDL
initrd = ramdisk-text.image.gz
initrd-size=16384
root = /dev/ram0
append = "video=atyfb:vmode:18,cmode:24"

It looks much like a quik.conf file. The "default=bootYDL" is ignored! 
I kept that line in all my boot.conf files, as I have no idea whether 
leaving it out messes things up. Default will alwyas be the _first_ set 
of entries in this file. At least that's what I found out. All other 
sets will be displayed as options, when hitting the spacebar at the 
initial "Tux Scenery" screen. Note the second set of entries, labled 
"install_YDL" - these are required for installing YDL through this 
method. All mentioned kernels _must_ reside in a folder called "Linux 
Kernels" on the root level of that partition, hence step c]. The 
ramdisk image, needed for installation must also be on the root level 
of the HFS partition - hence step d]. Take note, althogh currently 
working under MacOS, case sensitivity must be observed, as later while 
booting into Linux, it is required to keep entries in boot.conf 
according to the "real" names of the items on the HFS partition (kernel 
names, ramdisk name). The "timeout = 50" entry specifies, how long the 
initial screen will be displayed before booting into the default 
settings. Time is in 1/10 secs, so 50 means 5 secs, 100 = 10s ... In 
case you have to specify custom kernel parameters, you can have a line 
like:

append = "video=atyfb:vmode:18,cmode:24" (worked on my G3/233 DT ;)

It works much better than specifying the vmode and cmode settings in 
the displayd screen of miboot - somehow, these get scrambled when 
entered at the boot options screen, at least in the version of miboot I 
use. Any custom kernel arguments can be passed to the kernel this way. 
(I am writing this out of my memory, so the append line may be wrong, 
choose proper values for your setup or leave the line awy, miboot will 
then use the video settings set by MacOS. These can be controlled from 
within Linux via nvvideo - see man nvvideo)

c] a folder called "Linux Kernels" (note the space in that name) on the 
root level, containing your kernel/s. I usually have a second Mac that 
serves as a fileserver to get the stuff from the different CDs (YDL 
install CD ...). As of at least MacOS 8.1 and higher, the install CDs 
had a Chooser, so access to AFP servers is possible. It is possible to 
copy everything needed to a ZIP or such, before starting the process as 
well. You can use the supplied YDL kernel from a YDL install CD in most 
cases (exept for NuBus Macs, you definitely will need a custom kernel - 
if needed, I can supply one, as my Performa 5200 is running YDL 2.2 at 
the moment, waiting for 3.0 to be installed :)

d] to be able to install, we need the appropriate ramdisk on the root 
level of this HFS partition too. Copy the desired one (text or X11 or 
both) from your YDL install CD to the partition - do _not_ unpack 
it/them, leave it/them as is. BTW, as of YDL 2.3, text as well as X11 
worked fine for me - X11 needs more RAM, so in case you are short in 
RAM, use the text ramdisk image.


3]
Open the StartupDisk control panel and select the newly generated 
StartupDisk as the default StartupDisk and reboot. Upon the miboot 
screen, press <Space> to get into the otions screen, unload whatever CD 
is in the drive and insert the YDL install CD, choose your "install 
set" and hit boot. Hopefully you will see Tux greeting you at the top 
of the screen followed by the usual console messages.


4]
Everything from this point on should be according to YDL's 
documentation about installing YDL (or whatever distro you are 
installing - LPPC2kQ4 worked fine this way as well). Be sure to choose 
"Custom" as the install method, as the YDL installer will not recognize 
the "out of the ordinary" partitioning scheme, to be able to enter the 
correct mount points for your partitions later during the installation 
process. As for further partitioning your drive, _only_ alter the 
remaining free space of the drive, do _not_ alter any of your driver 
partitions (they are necessary for booting), nor delete or alter the 
HFS Boot partition you created earlier. In case you created two HFS 
partitions in step 1], simply delete the _last_ HFS partition (which 
you intended to use for Linux anyway) and create your swap and root 
partition. My drives look as follows (output from pdisk - I use 
/dev/sda2 for /home):

Partition map (with 512 byte blocks) on '/dev/sda'
  #:                type name      length   base    ( size )
  1: Apple_partition_map Apple         63 @ 1
  2:     Apple_UNIX_SVR2*untitled 2110748 @ 64      (  1.0G)

Device block size=512, Number of Blocks=2110812 (1.0G)
DeviceType=0x0, DeviceId=0x0
Drivers-
1:  23 @ 64, type=0x1
2:  36 @ 118, type=0xffff

partition map (with 512 byte blocks) on '/dev/sdb'
  #:                type name             length   base    ( size )
  1: Apple_partition_map Apple                63 @ 1
  2:      Apple_Driver43*Macintosh            54 @ 64
  3:      Apple_Driver43*Macintosh            74 @ 118
  4:  Apple_Driver_IOKit Macintosh           512 @ 192
  5:       Apple_Patches Patch Partition     512 @ 704
  6:           Apple_HFS "Boot_Linux"      65536 @ 1216    ( 32.0M)
  7:     Apple_UNIX_SVR2 swap             262145 @ 66752   (128.0M)
  8:     Apple_UNIX_SVR2 untitled        3849977 @ 328897  (  1.8G)

Device block size=512, Number of Blocks=4178874 (2.0G)
DeviceType=0x0, DeviceId=0x0
Drivers-
1:  23 @ 64, type=0x1
2:  36 @ 118, type=0xffff

In the mount points section of the installer you can specify something 
like "/mnt/Boot_Linux" as mount point for the HFS BootPartition 
together with type HFS, then you'll be able to access that partition 
from within Linux (that's the reason why we initialized it as HFS and 
not HFS+ in step 1]). You will certainly want to alter the boot.conf 
file on that partition at some stage. Do _not_ mount that partition at 
/boot, it will most likely mess things up. Partitioning schemes with 
more than one partition (besides swap) are possible and up to your 
taste.

Do not install any boot loaders from within the installer - not needed 
with miboot. I usually choose text as preferred login mehtod for the 
beginning untill I have solid XFree config files with proper screen 
resolutions - you may choose graphical in case you are sure your 
settings will work.


5]
After finishing the install you will have to edit the boot.conf file on 
your HFS partition to reflect the root partition of your linux 
installation. It will be mentioned by the installer at the end of the 
installation process. Write it down and put it in the appropriate line 
of boot.conf. There are several ways to accomplish that. One would be 
to boot with a MacOS CD again by holding down <C> and use SimpleText to 
edit the file. Another would be to enter the options screen of miboot 
and enter the root partition in the proper field (a predefined set for 
booting into Linux in boot.conf helps a lot - you safe some 
typing/deleting in that screen, as it is very slow), boot into your 
newly installed Linux installation and use any editor of your 
preference for altering the boot.conf file or completely write a new 
one, to get around the line breaking issue (Macintosh vs. Linux line 
breaks). It seems that the format of line breaks does not affect the 
proper funtionality of miboot, it is just annoying to have everything 
in one line under Linux.


I hope this will get your machine/s booted into Linux, using miboot as 
preferred booting mehtod.


Greetings,
Alex

Alexander Holst
Pforzheim University of Applied Sciences
<holst at fh-pforzheim dot de>