The ppc970 based machines, market-named G5, have been out and selling for a while now. A speed-bumped revision is expected for the next days. Is Linux already running on these new toys?
People get confused when it comes to answer this question. And they have their good reasons to look that confused. Anyway things are getting clearer and better, so let's look at what we have right now.



A look at the past

The PowerPC architecture always supported both 32 and 64 bit addressing. IBM for first started producing boxes with 64-bit cpus, so to have a complete 64 bit environment. At the moment 64-bit cpus are used in IBM machines, like iSeries and pSeries servers and on Apple machines, G5 and Xserve G5 at the moment.
First implementation of PowerPC 64-bit architecture was around 1995, so about 10 years ago.

And now?

Coming to these days let's see what we have.
The real problem simply seems to be that ppc970 machines are young. So people need time to work on the kernel to put support for new hardware. G5 machines were launched in August and the first ones shipped in mid-september. Before that date it was not possible for most (probably totally) linux-ppc developer to put their hands on the new Apple hardware.
A the moment the ppc64 port of the Linux kernel is not known to boot on G5, not for the main ppc64 tree at least. But work is in progress and considering that G5 is selling well bot h Linux developers and IBM are realy interested at getting a working kernel soon.

In the meanwhile one ppc Linux distribution, YellowDog, announced preliminary support for G5 machines.
Linux Distributions are allowed by the terms of the GPL License to distribute a custom kernel. This means that they can modify part of the code (for example to put new hardware support, as in this case) and redistribut it always in the limit of the GPL License.
People at YellowDog ath the moment are offering support for some parts of the new hardware: sound, for example, is not yet supported and video cards, both nvidia and ati ones shipped with the G5s, have only 2d acceleration, but the distribution is there and working . TerraSoft Solutions even sells G5s with Linux pre-installed.

You can look here at the YellowDog announcement about the preliminary support for 64-bit architecture. This a sort of second release for G5, as the first one was running with a 32-bit kernel.

Debian is known to have a full working ppc64 port, isos are downloadable from their site. The limit of usability is always in the kernel, that at the moment does not support all the features one would like to get from the G5 (one of the more popular problems is the fan control, as an example). Debian is always a good choice for its apt-get system and for the great work debian developers do.

Gentoo is in these days distributing on its site a live-cd for the ppc64 arch. Yes, that means that you can try Linux without having to install anything. All you need is on a CD, you follow the instructions, you boot it, you run it. Gentoo shares with Debian and YellowDog the same problems with hardware support.

Consider that the choice of all of the distributions for ppc64, Debian, YellowDog and Gentoo, at the moment, is always the same: 64-bit kernel with 32-bit user-space. Just some of the libraries are included both in 32 and 64-bit flavour. And mainly for scientific computation programs there is really the need to have a 64-bit compiled binary.