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on the G4 Mac Mini Index
This document will provide you everything you need to setup PowerLinux on a Mac mini. PowerLinux is a Debian-based configuration of Linux made to work on PowerPC processors such as are in the Mac mini. The hardware specification of the mini's is less than cutting edge by 2005 standards, but is still adequate for casual desktop or webserver use. One can choose between a 1.25GHz or 1.42GHz PowerPC G4, both running with 512K on-chip L2 cache and a 166MHz "MaxBus" front side bus. This is markedly less powerful than contemporary Intel or AMD x86 systems, but for the overwhelming majority of tasks this is more than enough processing ability. The advantage of the G4 used in the Mac Mini is that it produces very little heat relative to an x86 processor with comparable computational power, making it ideal for the small space inside the Mac Mini. The G4 used dissipates around 21W at 1.42GHz, and 18.3W at 1.25GHz. The other hardware in the box is also mature and reliable. The Mac Mini has an RV280 GPU ("Radeon 9200") with 32MB of dedicated DDR SDRAM. The RV280 has four rendering pipelines, hardware geometry transform and lighting acceleration, and both programmable pixel and vertex shaders. On the low end Mac Mini, the GPU is clocked at 250MHz and the graphics memory is clocked at 190MHz DDR. The system has a single DIMM socket which takes standard PC2700 modules, although it is slightly tricky to gain access to it. The largest available upgrade at present is a 1GB module, but I believe that the Mac Mini will also be certified for use with 2GB modules when they enter production. For the average Linux user, 1GB will be more than adequate. The 256MB Apple supply is far too little for Mac OS X. For heat and noise reasons, Apple have chosen to use a 2.5" (laptop-size) hard drive in the Mac Mini, making end-user upgrades fiddly and expensive. The 40GB or 80GB hard drive supplied is unlikely to be large enough for everyone. Apple appears to be shipping a mix of 4200rpm and 5400rpm units in the 40GB size, but currently all 80GB units are 4200rpm. The 5400rpm drives are apparently faster, presumably due to their shorter head seek times. My unit has an 80GB Toshiba MK8025GAS. The Mac Mini uses Apple's "Intrepid" north bridge. It appears to be a very compact derivative of the eMac's motherboard design. This diagram illustrates the hardware in the Mac Mini as exactly as I can. Note that the MaxBus and SDRAM are clocked at 166MHz, and the internal optical drive is configured as a slave device on the same ATA-100 bus used by the hard drive. This is a cost-saving measure on Apple's part, as the Intrepid chipset has a second ATA channel that could be used for the optical drive. The Airport card and Bluetooth modules are mounted on an optional mezzanine card. If your system did not come with either of these options, the mezzanine card will not be present. I am told that the modem is not present on models sold into the educational market. Apple's Developer Note on the Mac Mini is now online. |
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Upgrading the RAM requires opening the case. See this page, where you can download a nice PDF and a video showing how to disassemble the system. In fact, the PDF is a complete maintenance guide, presumably written for Apple service technicians. You'll need a putty/spreading knife, be sure to buy the very thinnest possible. The tool I used is extremely thin and springy and still it left little gouge marks on the base of the chassis. Please don't attempt to open your Mac unless you're familiar with opening consumer electronics devices. If you break your Mac, you get to keep both halves.
We hope soon that the 802.11g wireless ("Airport Extreme") will be working. A driver was announced in early December of 2005 at: bcm43xx.berlios.de/. Not sure about the modem or the optional Bluetooth module, have not tested either yet. Ben Herrenschmidt has fixed the audio driver. Apparently his patch is in kernel 2.6.12-rc4 or later, and you need alsa-lib 1.0.9rc3 or later. One odd problem :
Tools you will require:
The following process will erase your Mac's internal hard disk. Any data on it will be lost. Copy anything you value to another computer or onto writable optical media before proceeding. When you receive your Mac mini from Apple, it will have a single partition for Mac OS X which occupies the entire disk. In order to install Debian, you'll need to set aside part of the disk for Debian's filesystem. This process is called "partitioning". When we repartition the disk, any filesystems on it must be reformatted (or "re-initialised" in Apple-speak). If you have any valuable data on your Mac, copy it somewhere safe (preferably another computer) before proceeding. If you want your Mac to run only Debian, you can skip ahead to burning the installation CD. If you want to dual-boot Mac OS X and Debian, read on. With Mac OS X running, insert the gray "Mac OS X Install Disc 1" that you received with your Mac. Run the installer from the disc and, when prompted, click the "Restart" button. Your Mac Mini will reboot (bong!) and load the Mac OS X installer from the optical disc. If you've nadgered your OS X installation already, just reboot with the disc in the drive and hold down the "C" key on your keyboard -- this will force the Mac's firmware to try to boot from the internal optical drive. With the installer running, open on the "Installer" menu in the top left of the screen. Choose "Open Disk Utility". You'll now need to tell Disk Utility how to partition the hard disk. It is best to proceed withfive partitions. This is fine, we will re-assign their purpose in the Debian installer. Disk Utility is a little fiddly to use, but persevere and you'll figure it out in the end. A few tips: If you use the mouse to resize a partition below one gigabyte, it starts counting in megabytes instead. This allows you to type in the exact size you want for small partitions. To select a partition which is too small to be visible, click on another partition and use the tab key on the keyboard. This table shows how to partition an 80GB internal disk. In this instance,
there is an 8GB partition formatted as FAT32. This allows you
to easily and reliably share files between OS X and Linux, both of
which have good FAT32 support but, at the time of writing, poor or
incomplete support for each other's native filesystems.
A word of caution: Disk Utility can sometimes "lose" some space, presumably this is a bug in the software. Check that the partition sizes add up to the right amount when you're done resizing them. And remember than an 80 "marketing-gigabyte" disk contains only 74.5 "real-gigabytes". Once you're done, click the Partition button, quit Disk Utility, and install Mac OS X onto your new partition. Eventually the Mac will reboot into Mac OS X so you give all your personal details to Apple and then get on with life in OS X. Your computer now has some empty partitions for Debian to install itself onto. Next up you'll need a Debian Installation CD. Debian has several "branches", several of which are in continuous development. New versions of software are uploaded into the unstable branch. After a few weeks without serious bugs being found in unstable, the testing branch accepts these packages. Periodically Debian "freezes" testing and releases it as a new stable branch. A new branch is then created to become the new testing. I'm going to show you how to install "Sarge", which is the name for the current testing branch. It's not quite the white-knuckle-ride that the unstable branch is, and unlike the stable branch it contains pretty up-to-date software. It's the smart choice. Here's an outline of the process:
Run Safari and go to the Debian Installer page. Here you can download an ISO file, which is a filesystem image ready to be burnt onto a blank CD-R. Download the Release Candidate 2 ("rc2") version of the installer. If a more recent version is available, you may wish to try that instead. There are many different CD images available. You want one of the "powerpc" images. There are several different sizes available. If you connect to the Internet through your Mac's ethernet port, I'd recommend the businesscard CD image, which is about 110MB. This contains enough to install the base system without any further downloads. If you don't mind downloading a lot, or if you connect to the Internet through the Mac's internal modem, it might be a better idea to download the full CD set instead, as these include a snapshot of the most popular packages. Don't worry that there are 14(!) CDs, they are organised with the most popular software on the low numbered CDs. You can get a working system with just CD 1, I believe. Each full CD is about 650MB. Once you've got a lovely ISO, you'll want to burn it to CD. You can't just burn it as a file on a CD, the file is itself an image of a CD ("iso9660") filesystem. Open your "Applications" folder, then the "Utilities" folder, and run "Disk Utility" again. Sometimes it feels like this is the only OS X application I ever run. Anyway, from the "Images" menu select "Open". Find your ISO file and open it. Click on the ISO image and then click the "Burn" button on the toolbar. Feed your Mac Mini a blank CD-R. Before you reboot, you might want to flick through the Sarge installation manual for PowerPC. We're about to start Chapter 5. Reboot or power on your machine. Before the "bong!", hold down the "C" key. The bootstrap on the PowerLinux CD should load. If you just end up in OS X, try again. At the "boot:" prompt, just hit enter. The kernel will boot. After a few seconds, the installer will start and you'll be asked a few simple questions. Ideally you would be connected to the Internet through the Mac Mini's ethernet port, in which case you can tell the installer to use "eth0" as the primary network interface. After downloading the package lists, the installer will launch the partitioning tool. We've already partitioned our disk, but we need to use the tool to set the correct partition types. When prompted, choose to "Manually edit the partition table". If you followed a five partition plan earlier, this is what you want to end up with: |
When you're done, select "Finish partitioning and write changes to disk". For me, the installer complained that the FAT32 partition "had errors". I think this means that it couldn't format it, presumably because it's missing mkfs.vfat. Don't panic, just continue with the installation -- it's a simple problem to fix later. Debian will now install a base system. This is a system with enough tools to get started, connect up to the Internet and download any additional software you need. This step takes a few minutes. Eventually your Mac will spit out the Debian installation CD and reboot. Instead of rebooting directly into Mac OS X as before, it will now load a bootstrap from which you can hit the letter "L" to boot Linux, or "X" to boot Mac OS X. Tap "L" and, at the "boot: prompt, the Enter key. Debian will boot up and you can now complete your installation. The Sarge installation manual will guide you through the rest of the installation process, which is painless. If you're following along, start at Chapter 7.2.
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More Links
RedHat's FedoraCore on a MacMini HOWTO |