 | Level: Introductory Peter Seebach (crankyuser@seebs.plethora.net), Author, Freelance
05 Apr 2005 NetBSD and Yellow Dog Linux have both begun to support the Mac Mini. Peter Seebach looks at open source operating system options on this new contender in the embedded PowerPC platform space.
Apple's native operating system software offers you the best hardware
support on Apple hardware, and the Mac Mini is no exception. Some of the
hardware works just fine under open source systems; some isn't supported
at all, or works only partially.
This article looks at the current state of Linux™
and NetBSD support on the Mini. If you need all the hardware and options
fully supported, these open source options won't do it for you ... yet.
But, if all you need is a stable kernel, a C compiler, and network
support, the code is high-quality and the price is unbeatable.
Before you even think about installing a new operating system, make
backups. Conveniently, the Mini's hard drive will be 80GB or smaller, so
it's easy to back up everything on the disk. An external FireWire bay and
a large enough disk to make backups is a very good investment here. Make
backups. Really! Even if you're not going to install another operating
system, please make the tech support workers of the world happy and make
an extra set of backups right now, just in case.
Backups and system
partitions
One of the nuisances of Mac OS X is that the partitioning program takes a
very all-or-nothing approach to partitioning. If you alter any aspect of
the partition table using Disk Utility, all of the partitions on the disk
will be wiped. There are a few third-party programs that can move, copy, or even resize partitions (see Resources). If you want to use native utilities, your options are Disk Utility and pdisk.
As a result, repartitioning your disk to make room for a new operating
system will require a reinstall. The only way around this is to make space
on a second disk, or move your Mac OS X operating system to the second
disk. There's a program called Carbon Copy Cloner which can make a proper and bootable copy
of your Mac OS X system disk on an external disk (see Resources). Once you've done that,
you can boot from that disk, and repartition the internal disk.
The Mac OS X install disc that comes with the Mini won't let you install
directly to an external disk. It says this is because the computer can't
boot from an external disk, but in fact, it can. Simply copying files
over from your boot disk generally won't give you a bootable disk. This is
where a utility like Carbon Copy Cloner can be useful. The Mac is
friendly about letting you specify which of several partitions to boot
from, once you have installed the OS on them.
The partitioning scheme that will work for you depends a little on what
operating systems you want to load, and how much you'll be using each of
them. If you're going to run the machine as a dedicated BSD or Linux
system, it's a little simpler than if you're planning to dual-boot: you
can just dedicate the disk to your operating system of choice. For
dual-boot, you'll want multiple partitions, and you may end up reloading a
couple of times figuring out how much space to allocate to each system.
Formatting disks on the command
line
Partitioning and formatting can also be done from the command line.
(DOS/Windows® users will be comfortable thinking of partitioning as what
FDISK does, and formatting as what FORMAT does.) Partitioning can be done
using the pdisk utility program. Many other things can be done using the
diskutil program. The Disk Utility application performs the same kinds of
tasks as diskutil; diskutil is less restricted, but Disk Utility is
easier, and often safer. No matter what, you will need to boot from
another disk (the install CD will work) to repartition the hard disk in
your Mac, and you will lose all data on the disk when you do so. Did I
mention that you should make backups?
Yellow Dog Linux on
Power
Yellow Dog Linux (YDL) is based closely on RedHat's Fedora Core 2 operating
system; the installer will be immediately familiar to users who have
loaded Fedora recently (and easy to follow even if you haven't). YDL comes
on eight CDs: four install CDs, and four source CDs. That's a lot of CDs!
There isn't a DVD distribution available, and anyone who is used to the
modern Apple single-DVD distributions will find this a little frustrating.
Still, the install is easy, simple, and quick. Assuming, that is, you've
prepped the disk with some free space for the installer, or plan to
overwrite the whole disk. You can install YDL to an external drive, but
it requires more configuration and setup. It may be easier to install it
on the internal drive, and let Mac OS deal with booting from the external
drive. Either way, you're going to be doing some shuffling if you want to
keep your Mac OS X install.
If you find yourself thinking that your Mini isn't cute enough, and you
want extra cute, YDL provides instructions for repartitioning an iPod and
using it as the boot disk (see Resources). This
is awfully cool. It's worth noting that Yellow Dog Linux supports HFS+
file systems. This makes it easier to move files around, access your Mac OS
X backups, and so on. So, if you don't mind losing a chunk of your iPod's
disk to a Linux install, you can use it to test drive Linux. But before
you do this, again -- make backups. On the iPod, that means make sure
you've backed up all your songs, the firmware, and so on. The
instructions on the Yellow Dog site give more information about this (see
Resources).
YDL has a bit of experience improving Linux support for
PowerPC®, and some Mac-specific fixes as well. These will presumably make
it back into the main Linux tree, but they often show up in YDL first. The
company has been producing PowerPC Linux for quite a while, and also has
versions for the G5 and a number of non-Mac PowerPC boards. As is often
the case with non-x86 Linux distros, the source tree is not always
completely current, and there's a little bit of drift. But for anyone who
is concerned about PowerPC Linux keeping up with other branches, rest assured
that the situation has improved a great deal since the first PowerPC
patches were made available.
Hardware support
For a machine built from unusual parts, some of them laptop parts, the
Mini
was surprisingly functional before developers even had time to write any code
for it. For instance, the Yellow Dog 4.0 release, which didn't officially
support the Mini, installed and booted successfully, although it had some
video quirks. On February 9th, Terra Soft announced a new release with
support for the Mini. Even without this new release, the Mini was mostly
functional. The things lacking were Airport Extreme and audio. The video
worked, although it was stuck at 640x480. The hardware support is suspiciously
similar to what you get on some laptops.
Support is rapidly evolving. Announcements of test boots and driver patches
came out within days of the release of the Mini; the limiting factor seems to
have been limited hardware availability, not developer interest. Current
releases of Yellow Dog, as well as of Debian and Gentoo (both of which run
on the Mini), are stable enough for use.
Of interest to potential desktop users, the 4.0.1 release of Yellow Dog Linux,
while it doesn't add support for the Mini's onboard audio, does add support
for a USB audio adapter, the Griffin Technologies iMic. Given that the Mini
doesn't have an audio-in plug to begin with, this is a reasonable investment.
4.0.1 does fix the video stuff.
The point is, Linux support isn't perfect yet, but it's actively being
worked on. It can be fun being a part of an evolving platform; it can also
get in the way of work. You will want to base your decision on whether to
go with Linux now or wait for later, based on your needs.
The quick summary at the time this article was going to press was that
Bluetooth may work (but is not much tested), Airport Extreme isn't
supported, audio isn't supported (some people report limited success with
audio support, details in Resources).
Unfortunately, Airport Extreme support is probably not coming any time
soon, to Linux or any other open source system. Broadcom has not chosen
to make the necessary documentation available to open source driver
developers, and this leaves developers with no way of providing drivers
for the underlying chipset used in the Airport Extreme card.
It's quite possible that a future patch will add audio support. As I found
when messing with NetBSD, partial support might be fairly easy. I'd have
attempted it on the YDL install as well, but I'm not as experienced with
hacking on the Linux kernel.
Once audio support happens, YDL will be a pretty reasonable Linux
workstation. It's already a perfectly reasonable development platform, or
host for compiling PowerPC Linux executables.
Development tools
YDL, assuming you install the developer tools, comes with a fairly
large
collection of programming tools: Python, Perl, Tcl, and of course GCC
(version 3.3.3). No big flashy IDE, but the basic UNIX® development tools
are all there; Linux users coming from an x86 background will find it
familiar. Mac users will find the underlying tools familiar, but may miss
Xcode. Windows developers will want to look at online resources about
Linux development. The additional control over the machine is wonderful
once you've gotten over the shock, but it takes some getting used to.
See Resources for links on getting started
with Linux.
This suggests a possible niche for a Mini, as a PowerPC compilation server
(or even as a member of a compilation farm -- Resources has more). The Mini is not a dual processor
G5, but it's plenty fast to build PowerPC binaries of Linux applications. For
instance, a build of the entire gdb+dejagnu package took 11 minutes, 32
seconds, of wall-clock time. That's not incredibly fast, but it's
certainly fast enough for building the sorts of applications people
normally build. (These numbers were done on a 1.42Ghz Mini. It goes
without saying that this is far enough from a meaningful benchmark that
any light it sheds won't reach a meaningful benchmark within the next few
years.)
NetBSD on Power
NetBSD is, as the name suggests, one of the BSD family of UNIX-like
systems, based on the code released by the University of California,
Berkeley. It has been active on multiple platforms for a fairly long time.
NetBSD is an interesting choice to run on a Mac, simply because there's a
lot of NetBSD code (as well as the more widely acknowledged FreeBSD code)
in Mac OS X. NetBSD comes both in stable releases (NetBSD 2.0 being the
current release) and in the less-stable, but generally usable,
NetBSD-current.
From the point of view of a developer, NetBSD's big strength is simply
that all NetBSD ports are part of the same source tree. The macppc port
of NetBSD isn't tracking the "main" tree -- it's just another part of the
main tree. This isn't a branch or a development effort copying in
patches.
The NetBSD install doesn't give you much help with partitioning. Open
Firmware doesn't know about, and can't boot from, NetBSD's native version
of the Berkeley FFS (fast file system). The good news is, NetBSD-current
(but not the 2.0 release) supports Apple's UFS, which Disk Utility calls
"Unix File System," but which is really just a slightly different version
of FFS. You can use such a partition as your NetBSD root file system, and
share files with Mac OS X. Or, you can use the native FFS for your root
file system. Either way, you will need an HFS+ partition to hold the boot
loader. Users coming from x86 platforms will be familiar with the concept
of a boot partition used only to work within boot firmware limitations, as
will some users of older Macs which could only boot from the first 8GB of
a larger disk.
On the downside, NetBSD will require some hackery to get its partition map
configured. NetBSD uses a thing called a "BSD disklabel," which is an
entirely different way of describing disk partitions than the standard
Apple partition map -- but it's the same from one system running NetBSD to
another, even on different hardware platforms. NetBSD needs to have its
root file system as partition a, and swap partition (if any) on partition
b. That means going into the partition editor. By default, it'll have a
copy of the Apple partition map. What you need to do is find the
partition you chose for your root file system, and change partition a to
use the same start and end addresses as that one. Also, mark partition b
as unused, unless you're actually making swap space. (You can always
create a swap file later, if you didn't allocate a partition.) The
installer builds a partition table from the Apple partition map, by
default. This behavior is probably the best compromise, although it
guarantees that you'll have to do some work.
If you aren't running NetBSD-current, you have to make a new file system in
unused space on the disk. If you're running -current, you can use Apple
UFS for your NetBSD space. You still need an HFS+ boot partition to hold
the actual boot program, ofwboot.xcf, but that
program can find the kernel even if it's on a different partition.
This is a nuisance. It's not nearly as bad if you don't have to dual-boot,
because then you just need an HFS+ boot partition and your choice of
layouts of FFS partitions for your operating system and files.
Hardware support
NetBSD-current runs on the Mini without modifications. The first
reports
of this said to add the ehci driver, but it was
added to the default GENERIC kernel in January,
so it works beautifully now. All this does is allow USB 2.0 devices to
work at high speed instead of in compatibility mode, so if you don't have
that support right away, you can still use the system.
As with Linux, NetBSD has no support for the Airport Extreme card or
built-in modem. The video card shows up; the audio does too, if you build
a kernel with support for the snapper driver.
In a convenient coincidence, the driver doesn't support audio input, but
the Mini doesn't have an input plug. NetBSD doesn't automatically
configure and start X -- it boots to a console prompt. You can configure
XFree86 yourself (run X -configure, which will
create a new configuration file, which you can then edit and copy into
place) and start it when you log in.
The snapper should work fine. But in case it
won't attach to your hardware, go to the the /sys/arch/macppc/dev/snapper.c file, and look for
snapper_match(). The last check in that
routine is a comparison between the Open Firmware property compatible of the device, and the string "snapper."
Remove the check, and the device will start working. If you get error
messages trying to use /dev/sound0, try the
nearly equivalent /dev/audio0.
Development tools
NetBSD ships with the GNU C compiler. Unlike Linux and Mac OS, it
doesn't
ship with Perl, Python, and other third-party languages installed.
Instead, you build the ones you want from the packages collection. This
makes the core system install much, much, smaller, and is one of the
reasons that there's not a special "embedded NetBSD" project. On the
other hand, you can reasonably expect to spend a while installing
"fundamental" utilities after you get the system installed. Of course,
which utilities you find fundamental may vary from one person to another,
which is why this scheme remains popular.
The package system used on NetBSD is very similar in style and scope to
the Fink system popular on Mac OS X (if you are not familiar with Fink, it
will be discussed in greater detail in a future installment of this
series).
Summary
As of this writing, the hardware support in Linux and BSD isn't
complete.
Some of it (for instance, Broadcom drivers for Airport Extreme) may never
happen. Some of it is coming along swimmingly. In fact, I had to revise
substantial chunks of this article after I worked on another project for
just three days. The support work involved is often not difficult, and
the Mini has attracted a lot of attention.
If you want a friendly graphical install and no hassles with drivers, run
the proprietary Mac OS X. If you can live without drivers for some of the
hardware in the Mini and want to have complete source for everything
you're using -- or insist on an Open Source system -- Linux and BSD are
offering real and viable alternatives for getting the most out of your
Mini. And, for those following along with the Zork test, it works out of
the box on both Linux and BSD.
Resources -
Check out the other articles in this series.
- The first installment of this series was
An embedded view of the Mac Mini, Part 1: Apple's new PowerPC BSP.
- Among the third-party disk partitioning utilities are iPartition,
VolumeWorks,
Drive
Genius, and StorDirector.
-
Carbon Copy Cloner
might help you shuffle files around to make space for a second OS.
-
Excellent links about
partitioning Mac OS X can be found in this forum thread.
-
Alack, the YDL instructions are no longer online, but setting
up the iPod as a boot drive goes something like this. Note that Apple
advises against this use of the iPod's delicate drive; using the pod to
boot often would be a grave mistake. But for emergency recovery and
impressing guests it is more than viable.
-
Yellow Dog Linux 4.01, which
supports the Mac mini and iMac G5, is purported to have more than 70
updates over v4.0.
-
One of those updates is support for the Griffin iMic USB audio
adapter.
-
Terra Soft's Yellow
Dog Linux is based on Fedora
Core 2.
-
Terra Soft also sells 64-bit
high-performance Linux solutions.
-
Yellow Dog Linux is not the only Linux distribution that runs on the Mini.
Read about Debian Linux
on
the Mac Mini and about Gentoo
Linux
on the Mac Mini.
-
Linux attracts a great deal of attention, but it is not the only mature
open source operating system out there. BSD
systems differ from Linux in many ways, but two of the most obvious are
the license (a BSD license
instead of the GNU GPL)
and that BSDs are based on the old Berkeley Softare Distribution code (hence the name).
-
Answers.com has an overview of
differences between BSD and GPL licenses.
-
BSD comes in many flavors. The three most popular (in random order) are OpenBSD (supporting everything from
Alpha to Vax -- and including PPC), FreeBSD (x86 and SPARC only), and NetBSD home page (used by Peter in this
article, and supporting many platforms including ARM, MIPS, PPC and more).
-
The first successful boot of NetBSD on a Mac Mini was posted to a mailing
list two days before the machine shipped.
-
NetBSD's package
collection is actually supported on other OSs now, including Mac OS X.
-
Mac OS X has something similar to the NetBSD package system. Fink provides easy access to open
source software.
-
This message board thread discusses why there are
no open source drivers for Airport Extreme.
-
Audio still isn't fully supported on Linux yet, but some people have
reported at least limited success
with audio support on Linux on the Mac Mini so far.
-
Interested in the Mini's insides? Peruse the Mac Mini specs at
Apple's site, then view
its insides at mini-itx.com.
-
Set up your own compilation farm on the cheap with distcc: a fast, free distributed C/C++
compiler. distcc does not require all machines to share a file system, have
synchronized clocks, have the same libraries or header files installed --
or even to have the same processor. Some time ago, the developerWorks
Linux zone featured an article on how to Reduce
compile time with distcc (developerWorks, June 2004).
-
New to Linux? Here are some good starting points:
- Have experience you'd be willing to share with Power Architecture zone
readers? Article submissions on all aspects of Power Architecture technology from authors inside and outside
IBM are welcomed. Check out the Power Architecture author
FAQ to learn more.
- Have a question or comment on this story, or
on Power Architecture technology in general?
Post it in the Power Architecture technical forum
or send in a letter to the editors.
- The Power Architecture Community Newsletter includes full-length articles as well as recent news about members of the Power Architecture community and upcoming events of interest.
Learn more
about the Power Architecture Community Newsletter and how to contribute to it. Subscription is free.
- All things Power are chronicled in the developerWorks Power
Architecture editors' blog, which is just one of many developerWorks
blogs.
- Find more articles and resources on Power Architecture
technology and all things
related in the developerWorks Power
Architecture technology content area.
- Download a IBM PowerPC 405 Evaluation Kit to demo a SoC in a simulated
environment, or just to explore the fully licensed version of
Power Architecture technology. This and other fine Power Architecture-related downloads are listed in
the developerWorks Power Architecture technology content area's downloads section.
About the author | 
| | Peter Seebach has been using Macs since the Macintosh SE, and thinks this is the cutest one ever. He denies that his Mac Mini was ever lost in the couch. You can reach him at developerworks@seebs.plethora.net. |
Rate this page
| |
