It's an ill-fated time to be choosing between the two drivers with each party's work being just months old and the highly political issue of AtomBIOS being far from settled. Earlier this month Mandriva's Adam Williamson had asked such a question on the X.Org mailing list, but it was just greeted by flames. Ultimately, he had decided that Mandriva will utilize the RadeonHD driver as the default R500/600 driver for their forthcoming Mandriva 2008.1 release. In an email sent to Phoronix, Adam's reasoning for using RadeonHD is as follows: "Well, just that our aim is to provide the most useful support for the widest possible range of cards, and that both our own testing and the weight of advice from upstream developers is that radeonhd is the most appropriate driver for achieving that for r500/r600 cards in 2008 Spring. It's easy for us to switch the definitions, so we'll re-evaluate the position of the drivers before our next release, Mandriva Linux 2009." At this time in their Mandriva 2008.1 development cycle, they are using a git snapshot from right after the driver's most recent changes with adding Radeon HD 3400/3600 support. Mandriva 2008.1 also provides the most recent fglrx driver (for those opting to use binary blobs) and the latest Radeon 6.8.0 driver for earlier ATI products.
On the other hand, Ubuntu 8.04 LTS will ship with xf86-video-ati driver. The version shipping in Ubuntu is xf86-video-ati 6.8.0, which shipped last month and contains the R500/600 AtomBIOS support along with initial Render acceleration support for the R300/400 series, all contained drivers now using libpciaccess, and many other changes. While RadeonHD isn't the default, it currently can be found in the Ubuntu Universe repository. For Ubuntu 8.04 "Hardy Heron" they have gone with xf86-video-radeonhd 1.1. While version 1.1 is their latest official release, it is vastly outdated and was released last December. This driver version lacks support for the R500 XAA/EXA acceleration, Radeon HD 3400/3600 series, and a large quantity of other changes done within the git tree over the past three months. Unfortunately, RadeonHD v1.2 isn't expected for release until later this month, but in the future, they intend to be pushing out releases more often. It's unlikely that the xserver-xorg-video-radeonhd package will be updated to version 1.2 for Hardy Heron, so users will want to build the driver from source.
Also using the Radeon driver as the default is Fedora 9. The Fedora Rawhide repository for the upcoming Sulphur release currently has xf86-video-ati 6.8.0. While RadeonHD isn't the default, xorg-x11-drv-radeonhd can be installed from the Fedora repository. With Fedora living on the bleeding-edge of software development, the version of RadeonHD in use right now is a git snapshot from March 1, 2008. It is important to note that David Airlie and his contributions toward the xf86-video-ati driver is part of his work for Red Hat.
For OpenSuSE users, RadeonHD git snapshots from March 13 are available in RPM form for OpenSuSE 10.2, OpenSuSE 10.3, OpenSuSE Factory, and SuSE Linux Enterprise Desktop 10. Sun Microsystems has already adopted the RadeonHD driver for their newest OpenSolaris and Solaris Express editions.
Fortunately, most distributions with refreshes this spring offer both Radeon and RadeonHD packages so that the user can choose which driver they would like to utilize. Hopefully by later this year, however, the debate of Radeon vs. RadeonHD with regards to AtomBIOS will be settled and ideally increased collaboration between the two projects. AMD is pressuring the RadeonHD developers to use AtomBIOS and they have with the Uniphy transmitter and they may use AtomBIOS a second time with the AMD 780G IGP support. When it comes to the 3D support, there will be the first-cut Mesa driver for Radeon X1000 and Radeon HD 2000/3000 support, but to follow will be the much-anticipated AMD Gallium3D driver (Q1'08 Gallium3D Update).
On the NVIDIA side, distribution vendors may soon find themselves in a similar boat choosing between the official xf86-video-nv 2D driver and the reverse-engineered Nouveau driver, which will be capable of both open-source 2D and 3D support.
Which open-source driver are you using? Tell us in the Phoronix Forums.