Xeon Skylake Users May Run Into Display Problems With Current Distributions
Yesterday I finished building my Xeon E3 1245 v5 Skylake system. I'll have benchmarks and more details on that SKL Xeon setup shortly on Phoronix, but just wanted to put out a brief message about the display problem in case other people run into this issue and are searching for a solution.
The Xeon E3-1245V5 features HD Graphics P530 and while my other Core i5/i7 Skylake systems did work fine out-of-the-box with graphics/display support on Ubuntu 15.10, that was not the case for this Xeon system with its "WKS GT2" graphics. When I was booting a live Ubuntu USB device, I would keep losing the display as the boot process was finishing. Ubuntu 15.10 uses the Linux 4.2 kernel with various Skylake patches added in.
It was odd this Xeon Skylake issue was having display issues since the i5-6600K, i5-6500, and Pentium G4400 had worked out of the box on Ubuntu 15.10. After a few reboots and the problem persisting, I ended up booting Ubuntu with nomodeset.
Once booting with nomodeset to stop the Intel DRM driver, the system powered up fine and I hit the Unity desktop. (Side note: surprisingly, the VESA DDX driver was mode-setting fine with this P530 connected via HDMI to this Dell 4K display! It went straight to 3840 x 2160, albeit the desktop was painfully slow as the LLVMpipe software fallback had to deal with the 4K desktop.)
After that and installing Ubuntu to the system, I then just switched over to a VT and downloaded a Linux 4.4 Git kernel from the mainline kernel PPA. After booting into the Linux 4.4 kernel, the WKS GT2 graphics of the Xeon E3 1245 v5 worked right away!
OpenGL acceleration was working with the HD Graphics P530 on the stock Mesa 11.0.2, but quickly after that I switched over to Mesa 11.2-devel for best support. So long story short, if you run into display issues on a distribution booting a Xeon Skylake system with Linux 4.2 or older, take the nomodeset route and then upgrade the kernel. I went straight to Linux 4.4 so I don't know offhand if Linux 4.3 stock would fix the situation, but for new hardware I always prefer running the very latest kernel possible.
Stay tuned for Xeon Skylake tests shortly.