I'm experiencing this issue on my mom's computer, a Gateway system with an AMD A6-5400K APU (Radeon HD 7540D graphics). The behavior Jaap Woldringh describes is exactly what I'm seeing. I boot an Ubuntu 16.04 liveDVD and I get the black screen. If I reboot from the liveDVD and specify "nomodeset", the system boots but in low resolution. When I look at the Xorg.0.log file, I see the "No UMS support in radeon module" message.
What's interesting is I booted the same liveDVD on another system, an HP with an AMD A8-5500k APU (Radeon HD 7560D graphics) and it booted just fine, no issues at all. My mom's Gateway system is currently running Ubuntu 14.04.2 without any issues and at full resolution. Of course, I would like to get this resolved before I attempt to upgrade her system to 16.04.1. :) Thanks! -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1568211 Title: Unable to boot Status in linux package in Ubuntu: Incomplete Bug description: I upgraded overnight from Wily to Xenial. The system will not boot. Only a blank screen after grub loads the kernel. The recovery kernel loads fine and I was able to find the following messages: [drm] VGACON disable radeon kernel modesetting [drm:radeon_init [radeon]] *ERROR* no UMS support in radeon module! The recovery kernel command line had a nomodeset parameter that was not in the main kernel command line. Note: For what it's worth I reported a similar issue against several Utopic kernels (bug #1407505). There was a back and forth with jsalisbury until a kernel finally worked. I have had no problems until today. WORKAROUND: Adding the nomodeset parameter the main kernel command line finally booted the system. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1568211/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp