I upgraded from Ubuntu 14.04 LTS to 16.04.1 LTS AMD-64 desktop, and the computer now boots to a black screen. After the BIOS screen there is no signal to the monitor on neither the VGA nor HDMI ports. I can hear the bongo drums from the login screen, and I can SSH into it from another computer, so Ubuntu is running, just with no display. Occasionally I get the GNU GRUB menu, but the screen goes black after I select something.
Suspecting that something got corrupted (I got four System Problem Detected messages during the update) I tried booting, not installing, from a 16.04.1 installation DVD: same result.
I have the AMD A10-7850K Kaveri APU (on-chip graphics) on a Gigabyte F2A88XM-D3H motherboard.
From conman253's reply to this question, I tried "man amdgpu" and "man radeon", and the Kaveri APU is listed as supported hardware for the radeon driver.
Some more information from the system:
$ lspci | grep -E "VGA|3D"
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Kaveri [Radeon R7 Graphics]
$ sudo lspci -v -s 00:01.0
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Kaveri [Radeon R7 Graphics] (prog-if 00 [VGA controller])
Subsystem: Gigabyte Technology Co., Ltd Kaveri [Radeon R7 Graphics]
Flags: bus master, fast devsel, latency 0, IRQ 39
Memory at c0000000 (64-bit, prefetchable) [size=256M]
Memory at d0000000 (64-bit, prefetchable) [size=8M]
I/O ports at f000 [size=256]
Memory at feb00000 (32-bit, non-prefetchable) [size=256K]
Expansion ROM at feb40000 [disabled] [size=128K]
Capabilities: [48] Vendor Specific Information: Len=08 <?>
Capabilities: [50] Power Management version 3
Capabilities: [58] Express Root Complex Integrated Endpoint, MSI 00
Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
Capabilities: [270] #19
Capabilities: [2b0] Address Translation Service (ATS)
Capabilities: [2c0] #13
Capabilities: [2d0] #1b
Kernel driver in use: radeon
Kernel modules: radeon
Is it possible to make this work in 16.04.1? Reverting back to 14.04.4 is an option I suppose, but doesn't that require a clean install?