The Radeon HD 7900 series were announced at the end of 2011 and since then the Linux support status for this hardware has remained a big question. For the Radeon HD 7000 series "Southern Islands" GPU launch, they did not send over any hardware samples so Linux consumers have left to be confused over the state of the non-Windows support for AMD's hardware based on the "Graphics Core Next" architecture. Fortunately, here is finally an extensive look at the Radeon HD 7000 series on Linux with testing of a Radeon HD 7950.
Even while AMD has rounded out most of the Radeon HD 7000 series family since the HD 7950/7970 cards with the launches of the Radeon HD 7700 and Radeon HD 7800 series, the Linux support state has remained un-clear. The only thing that has been known for sure is that there is still not any Radeon HD 7000 series open-source support. In the nearly four months since the Radeon HD 7900 series were announced, no open-source code has yet to arrive for either the Linux kernel DRM driver, the X.Org DDX driver, or the new Gallium3D driver. AMD is working on this support as they have been saying within our forums for months, but there is no word on when it may arrive or with what limitations. The latest guess/hope is that they will hopefully have at least the kernel bits ready for Linux 3.4.
What has made the Radeon HD 7000 series situation so murky has been the Catalyst for Linux driver state. That is not black and white. AMD hasn't been shipping same-day Catalyst Linux drivers on the new hardware at launch like is the case for Windows, where that month's Catalyst driver already supports the hardware or they issue a hot-fix driver that day. For some of the GCN hardware, AMD has released hot-fix Linux drivers to provide GPU enablement support, but it has been weeks after the hardware first ships (two weeks after the fact in the case of the Radeon HD 7700). Then even months later for existing hardware, the Catalyst driver still displays a watermark on the screen saying the hardware is "unsupported" by the driver. Even when using the very latest Catalyst press driver with the Radeon HD 7950 on Linux, there is still an unsupported hardware watermark, albeit there's working functionality of the Tahiti card.
To try to clear up the situation for Linux users, while AMD has yet to send out any hardware for Linux tests, I ended up buying a Radeon HD 7950. At a cost of $470 USD, the card I ended up going with was an XFX Radeon HD 7950 Black 3GB (XFX FX-795A-TNBC). This Radeon HD 7950 graphics card is the focus of testing in this article as we look at how well the Tahiti Pro GPU from the Southern Islands family works with the Catalyst for Linux binary driver.
The Radeon HD 7950 GPU packs over four billion transistors (roughly 4.3 billion) on a 352 mm2 die, has 3GB of GDDR5 video memory on a 384-bit bus, a reference core clock speed of 800MHz, a reference memory clock speed of 1250MHz, and is capable of up to 2867 GFLOPS. Like the other "Southern Islands" graphics cards, the Radeon HD 7950 is manufactured on a 28nm TSMC process, OpenGL 4.2, Microsoft DirectX 11, Eyefinity support, HD3D technology, PowerTune, PowerPlay, CrossFireX, and supports PCI Express 3.0 x16. As much time has passed since the launch of the Radeon HD 7900 series, most of you have already likely read at length about Graphics Core Next and these new GPUs, so the GPU overview will be left at that and we'll focus on the Linux aspect.