[UFO Chicago] debian woody on an imac rev. b -- success!

Peter A. Peterson II pedro@tastytronic.net
Fri, 10 Jan 2003 13:34:13 -0600

So, I inherited a lime-green iMac from someone recently, but had been
having trouble getting it to work.

So here's my little howto, because I finally figured it all out.

First of all, don't use potato. You'll have problems with Potato PPC
Cds. (Specifically, QUIK did not make it bootable from the hard disk.)

iMacs are "New World" Macs, which means that you can avoid a lot of
the voodoo that you had to do in order to make them boot Linux --
these guys can do it natively.

Anyway, I used the LordSutch PPC Net-install .iso, which is available


I used the woody-powerpc-1 iso.

Partitioning the Hard Disk:

If you don't want anything else on that disk, use i to erase the map
and start fresh. If you want MacOS on this box again sometime, you
shouldn't delete the driver partitions unless you know you can restore

Next, create the boot partition using b or use C to create a new
partition and specify the type as Apple_Bootstrap and make it 800K.
This is where yaboot will reside.

Next, create your other partitions.

Swap on PPC is just another partition, so don't try to specify the
type like you do on i386 -- just make the partition, and name it
simply "swap" -- the installer will know what to do with that

Create your other partitions willy nilly and go with the flow.

Network Support:

I was thrown by this initially because I didn't see any NIC module
that looked appropriate... because it's not there. The iMac uses the
Apple BMAC+ NIC which is compiled into the PPC kernel, so you don't
need to mess with it. Just tell it to use DHCP (or set your own info)
and you're set to jet.

Everything else is the way you'd expect it -- and it reboots nicely.

Sound Support:

PPC Hardware support is much better in the 2.4 trees, so make sure you
are using a 2.4 kernel or install a 2.4.x-image-newpmac kernel image
and reboot or else you'll have trouble with sound.

The module for the sound card on an iMac Rev. B is "dmasound" and is
in the /lib/modules/2.4.18/kernel/drivers/sound/dmasound/ directory.

	modprobe dmasound_pmac

to load the sound modules. Modprobe will load the other modules
necessary. You probably want to add 'dmasound_pmac' to /etc/modules so
that it will load at boot time. You may also want to play with
permissions so that normal users can play oggs and whatnot.

USB Support:

This Just Works(tm) with the woody netinstall iso I used, so I'm not
sure what had to be installed to make this work, but it detects the
USB keyboard and mouse the way you expect it to. You even get to see
cool little kernel messages in the console when you unplug and replug
the devices in. I realize this is mundane, but be honest, it's pretty

X Window Support and XF86Config-4:

This was by FAR the hardest thing I had to deal with. There are two
secrets that were extremely hard for me to find (which is really why
I'm writing this message).

1. The pointer is /dev/input/mice and uses the ImPS/2 Protocol.

Ok, that wasn't hard to find... but this was:

2. The iMac's built in monitor uses a FIXED 60Hz refresh rate and a
variable vertical refresh rate of 75-117 Hz.

If you set *anything* other than 60 for the horizontal refresh your
monitor will go out of sync, even though X is set up right, even
though you might set it to 640x480 8bpp... and I dug for a long time
before I found this post:


So I did a dpkg-reconfigure xserver-xfree86. The chipset is ati (the
Rev. A&B iMacs have an ATI Mach64 video card), I said yes to using the
kernel framebuffer, and selected Advanced for the monitor setup and
put in that refresh information and selected 1024x768 (the max
resolution on that screen) in 16bpp. It may be possible to run
1024x768 in 24bpp depending on your VRAM, but I don't really care
about it, so I didn't try. YMMV.

That's it. Good luck, and feel free to ask questions if you have
them. Also, I hope that other Debian hackers find this post, since a
few of these pieces of information were pretty hard to find. There are
some other resources for this stuff on the net, notably
http://www.imaclinux.net/ but the forums appear to be somewhat dead.

The best info I found was by intentionally searching mailing lists by
searching for 'debian powerpc imac xf86config-4' rather than just
searching for 'imac linux xf86config-4' or something like that.

Happy Hacking,


Peter A. Peterson II, technician and musician.
---=[ http://tastytronic.net/~pedro/ ]=---