The Khronos Group wants the world to know that Vulkan, its next-generation graphics API, will not restrict multi-GPU support to Windows 10.
Vulkan debuted in March 2015 with the goal of taking on AMD's Mantle, DirectX 12, and other graphics APIs. It quickly found its way into smartphones thanks to support from Google, Samsung, and other Android smartphone manufacturers, and PC games like Doom and Dota 2 were also updated to take advantage of the new API. Other titles, like the upcoming Star Citizen online game from Cloud Imperium Games, chose Vulkan over DirectX 12.
And that's just Vulkan's start. Khronos announced at GDC 2017 in February that "all major GPU companies" have shipped Vulkan drivers for both mobile and desktop platforms, that game engines like Unity and CryEngine will support the API, and that it's been built into the Nintendo Switch console. (Khronos also revealed the OpenXR working group, which is dedicated to improving VR and AR development, as well as updates to other APIs.)
One of the biggest Vulkan updates revealed at GDC 2017 was multi-GPU support. That's where this clarification about Windows 10 comes in. Khronos said in a blog post that "one key question" it's been asked since GDC 2017 is "whether the Vulkan multi-GPU functionality is specifically tied to ship only on Windows 10." Here's from where Khronos thinks that confusion stemmed:
Some of the Khronos GDC presentations mentioned that for Vulkan multi-GPU functionality, Windows Display Driver Model (WDDM) must be in Linked Display Adapter (LDA) mode. That was not a very clear statement that has caused some confusion. And so it is worth clarifying that: The use of WDDM is referring to the use of Vulkan multi-GPU functionality on Windows. On other OS, WDDM is not necessary to implement the Vulkan multi-GPU extension. On Windows, the use of LDA mode can make implementing Vulkan multi-GPU functionality easier, and will probably be used by most implementations, but it is not strictly necessary. If an implementation on Windows does decide to use LDA mode, it is NOT tied to Windows 10. LDA mode has been available on many versions of Windows, including Windows 7 and 8.X.
Khronos also reiterated that it "always strives to make its specifications as cross platform as possible" even though "what products ship on which OS is up to the implementers of each specification." Vendors already plan to bring Vulkan's multi-GPU support to non-Windows 10 platforms, including Linux, Khronos said. So don't worry--you won't have to use Windows 10 to enjoy the power of multiple GPUs via this up-and-coming graphics API.
That said, Vulkan looks to be doing the same thing, except that NVidea users also get to enjoy it, so it's even better!
Vulcan's main purpose was to provide a unified graphics and compute API to replace OpenGL. Taking on Mantle and DX12 came later.
(Note: Kronos Group is also currently administering the OpenGL API as well)