Small Systems and Big Iron: Linux on Non-x86 Computers
The PowerPC architecture was jointly developed by IBM and Motorola around 1990 and is used on a very wide range of devices. All three current major game consoles use PowerPC-based processors, as do many routers, onboard computers in cars and aircraft, and high-end servers from IBM. Although PowerPC largely has faded from desktop computers since Apple switched to Intel x86 in 2006, use of the processor for embedded and server purposes remains a multibillion-dollar industry.
During the peak of PowerPC desktop usage, most Linux distributions offered builds for the architecture. Sadly, this is no longer the case. Novell and Red Hat both offer Enterprise Server distributions for Power, but they aren't cheap and really are designed only for current IBM servers. Although their distributions are mature and well supported, most consumer PPC/Power hardware actually consists of older Macs and the EFIKA line of computers from Genesi. For these systems, the Enterprise Server distributions of SUSE and Red Hat Linux aren't really optimal. Thankfully, the Linux community still provides quite a bit of support for this architecture, largely due to the significant amount of inexpensive PPC hardware from before Apple's switch to Intel. The Sony PlayStation 3 also has provided the Linux community with inexpensive, but powerful hardware. Its main limitation is the fact that it has only 256MB of RAM.
Historically, one of the primary Linux distributions for PowerPC was Yellow Dog Linux. YDL is based on Red Hat Linux and uses RPM to manage packages. Its hardware support is generally quite good. The distribution runs on PowerPC Macs, IBM servers and workstations, and the PlayStation 3. YDL has some fairly significant differences from other distributions, such as using Enlightenment 17 as the default desktop environment. E17 offers quite a few advantages over both Enlightenment 16 and conventional desktop environments. It's far lighter on resource consumption than KDE, GNOME or Xfce, while offering a much larger feature set than most low-footprint window managers. Almost every element of the user interface is customizable with graphical tools and plugins. E17 also includes a built-in file manager, unlike previous versions. However, E17 still is under heavy development and may not be as stable as mature versions of GNOME or KDE. For users who prefer them, Yellow Dog also has packages for other desktop environments and window managers.
Fedora also offers up-to-date PowerPC ISOs of every version, including the latest, Fedora 12. Fedora offers a more complete default installation and more application packages, but also is considerably more resource-intensive. It attempts to give a GNOME or KDE environment comparable to the x86 build of the same version. This means if you're used to Linux systems on x86, you'll be more at home with Fedora than with Yellow Dog, but it also means it's noticeably sluggish on older systems. Generally, I'd recommend Fedora for systems with a 1GHz or faster G4 or G5, and at least 512MB of RAM. It is important to note that support for Fedora on the PlayStation 3 is experimental and in a very early development stage, although there have been efforts to finish the port. Fedora 12 will be the last officially supported version for PowerPC, but there are efforts to provide community-supported PowerPC builds of Fedora 13 and later versions.
Ubuntu ended official support for PowerPC in late 2006 with Ubuntu 6.10. Since then, there have been PPC builds of every Ubuntu release developed by the community. These generally are very high quality and have excellent stability. Ubuntu has similar system requirements to Fedora, with most older hardware probably being too slow to handle it smoothly. Ubuntu also offers an ISO for the PlayStation 3, but it's still experimental and somewhat limited in features due to the PS3's insufficient amount of RAM, so using the live CD is likely to be unpleasant.
Itanium, also called IA64, was the last attempt by Intel to replace the aging x86 architecture, following the disappointing iAPX432 and i860 processors in the 1980s and 1990s. At one time, industry analysts considered it to be the future of the high-end servers, and Intel planned to use the architecture in personal computers eventually as well. Itanium uses a unique architecture, neither RISC nor CISC, that can execute several instructions per cycle in parallel. SGI and HP replaced their own high-end processors with Itanium out of the expectation that it would bring a revolution in performance. However, the first-generation Itanium core, code-named Merced, delivered disappointing performance results while consuming massive amounts of power and prevented the market-share breakthrough that Intel had hoped for.
With the release of the Itanium 2 core in late 2002, performance increased significantly, but the platform's reputation had been hurt by the low quality of the first-generation processors, and Itanium remains a high-end product with low market share. Intel still claims to be committed to the architecture. A new quad-core Itanium chip, code-named Tukwila, was released in February 2010, and according to Intel, at least two more generations are under development.
HP is the last major manufacturer of Itanium-based workstations, and it still makes more Itanium servers than all other companies combined. HP's workstations, the ZX2000 and ZX6000, are easily available secondhand and have excellent Linux support.
The only remaining commercial distribution with any focus on Itanium is SUSE Linux Enterprise Server. Red Hat offers a version of Red Hat Enterprise Linux for Itanium, but support for the platform will be ended in version 6. Red Hat Enterprise Linux 5 will be maintained and receive bug fixes until 2014, so if you don't mind missing out on feature updates, you can purchase a license from Red Hat. Red Hat also offers a free trial version, which blocks access to update repositories after 30 days.
If you have a large Itanium system or cluster, SUSE Linux makes a lot of sense due to its active development status and excellent support for virtualization, but for smaller installations and hobbyists, several other systems are available, including Gentoo and Debian. Fedora and Ubuntu both define Itanium as a secondary platform and occasionally provide new releases or updates, but both largely have ignored the architecture in recent releases. The last build of Fedora available for Itanium was Fedora 9, and Ubuntu releases for the platform have been broken or seriously buggy since 8.04. HP-UX, OpenVMS and Microsoft Windows also are available for Itanium.
Debian probably is the most stable and modern IA64 Linux distribution available for free. It still is an officially supported Debian platform, and still is under active development. It offers all the features of x86 Debian, including a full GNOME desktop environment. Debian for Itanium has access to the full Debian package set and generally is fairly stable. In recent months, development has declined somewhat due to declining overall interest in the Itanium platform, but it appears that IA64 will continue to be a supported platform for the foreseeable future. An occasionally active mailing list exists for users and developers of the Itanium port of Debian.
Red Hat and its derivatives occasionally have run on Itanium. Red Hat is preparing to release Red Hat Enterprise Linux 5.5, which will support the platform natively, but it might not be a good idea to run RHEL on a new Itanium system due to the fact that version 5 will be the last release available for IA64. CentOS, an open-source clone of RHEL, no longer supports Itanium, although the developers have suggested that future releases may run on it, as well as other less-common architectures including SPARC and Alpha. Fedora was available for Itanium through version 9, and some RPMs from version 10 are available. Overall, the Fedora experience on Itanium isn't bad with all updates installed, but users who want more up-to-date packages may end up needing to use source RPMs or compiling software themselves.