AMD A10-7850K Kaveri: The Linux Introduction
AMD's PR department sent over the A10-7850K along with an ASUS A88X-Pro motherboard, 2 x 8GB of DDR3-2133MHz AMD Radeon Gamer Series Memory, and a chassis with flame decal and Xion 700 Watt power supply. Windows reviewers also received a Samsung SSD with Windows 8 while obviously that was not included for our Linux testing purposes.
Now onto the Linux support... The latest daily development ISO of Ubuntu 14.04 (2014-01-11) was used at the time of testing to best represent the very latest Linux experience on AMD's Kaveri. Ubuntu 14.04 in its current development form is running on a near-final version of the Linux 3.13 kernel, Mesa 10.0.1, and GCC 4.8.2 compiler. With the A10-7850K and ASUS A88X-Pro, the Ubuntu 14.04 image on a USB drive booted successfully. The only problem experienced right away was the lack of any graphics acceleration.
AMD Kaveri On Open-Source Linux
The Radeon R7 Graphics on the AMD Kaveri APU are not supported "out of the box" on Ubuntu 14.04 at this time, let alone the current stable Ubuntu 13.10 release. While the initial open-source support for Kaveri was published this past summer, when booting to the desktop, there's only poor software acceleration provided by the LLVMpipe Gallium3D driver. The Linux 3.13 kernel used by Ubuntu 14.04 did successfully load the Radeon DRM driver on Kaveri with kernel mode-setting support. Upon loading the X.Org Server, the xf86-video-modesetting driver was loaded automatically after xf86-video-ati started. The Radeon DDX driver currently packaged in Ubuntu is too old and missing the Kaveri PCI IDs, etc. When falling back to the xf86-video-modesetting driver, the Gallium3D LLVMpipe driver is automatically used for software acceleration. The xf86-video-modesetting driver has no hardware acceleration or other useful functionality and in our hardware configuration led to a skewed cursor and other rendering issues.
For trying to get Kaveri working with the open-source driver, I then updated the xf86-video-ati code from Git. When using the latest xf86-video-ati open-source driver code, Kaveri was properly detected as indicated by the Xorg.0.log. However, when the X.Org Server started, the screen remained black and nothing appeared ever on the display nor was anything outputted to the X.Org Server log after reporting it was using RadeonSI and initializing GLAMOR. This was with the Mesa 10.0.1 driver packages in Ubuntu 14.04. Lastly, I tried adding in Mesa from Git master (Mesa 10.1-devel) but here when launching the X.Org Server and going with GLAMOR for 2D acceleration, there was a segmentation fault.
Long story short, there is open-source driver code available for the Radeon R7 graphics on the AMD A10-7850K "Kaveri" APU, but it doesn't appear quite ready yet and isn't found "out of the box" in the current development version of Ubuntu. The code should hopefully be in good shape though prior to Ubuntu 14.04 LTS in April and other Linux distribution releases in the months ahead. When time allows in the coming days I'll play more with the latest Git code to try to get the open-source RadeonSI Gallium3D driver with Linux 3.13 DRM working on Kaveri.