ubuntu is faster than steam os.
Why do they even bother?
On the contrary Windows 10 is the biggest reason for SteamOS to exist.
Khronos absolutely needs to stop fucking around and get Vulkan out of NDA though. This is getting ridiculous and we need an answer to important questions like whether AMD really intends to only officially support GCN 1.2 hardware.
AMD is going to support all GCN until it moves on to a new arch.
An API that looks like it'll arrive too late to make a difference. DX12 is already here and devs are developing for it.
AMD have so far only talked about Vulkan support via AMDGPU, the new driver for GCN 1.2. Worryingly in their official GPU feature comparison tool GCN 1.0 and 1.1 hardware they also include a "Vulkan API" point which is only marked "Yes" for 1.2 hardware.
Right, maybe they'll change it once AMDGPU is mature retiring the support in Radeon in favor of the new driver but right now its only for GCN 1.2 hardware.
On the Mesa side of things RadeonSI supports all GCN hardware so we're still in good shape there except that AMD still has this fantasy that people want to use their OpenGL stack and they haven't gone all in on backing Mesa financially and with developers.
We'll probably get Vulkan on older cards, but it will only be through the open source drivers and that may take a while since only the closed source driver devs have access to the API.
I'm using amdgpu with a custom patched kernel. 4.4 + "powerplay" reclocking patches. Huge performance boost over plain 4.4
So far every game I've tried, proprietary or not, works flawlessly. I don't know about the speed but it's usually sufficient at 1200p.
R9 380 (GCN 1.2 Tonga)