On Linux is different, AMD is implementing a new open driver in parallel with a closed one, AMDGPU (based on the current open mesa radeonsi) and AMDGPU-PRO (using the Windows OpenGL and Vulkan components, the idea being to use the profile optimizations that professional programs need), the open one has alpha support for GCN1.0 and beta for GCN1.1, the AMDGPU-PRO has full support, but is a worse driver than the open AMDGPU. Support for Vulkan on AMDGPU-RPO is a given as it is the same one in use on Windows, but for AMDGPU you have to use the open RADV driver, that is not made by AMD (they did say they will open their Vulkan driver and fuse it with RADV, along with OpenCL). As GCN1.0 is no compatible by default with AMDGPU, you don't get a Vulkan driver unless you use AMDGPU-PRO.