Those who want their Linux to be totally open saucy will be completely disappointed. In fact, there is a lot about the project, which is closed source.
AMD said that OpenCL support will initially be closed and then opened later. They already have some basic OpenCL open-source support via the Clover Gallium3D driver; this is referring to OpenCL 2.1+ support with SPIR-V alongside Vulkan or the OpenCL Catalyst code.
Vulkan driver communicating with libdrm that interfaces with the AMDGPU kernel driver. AMD slides do not mention whether they intend to support Vulkan with the current Radeon DRM driver for HD 7000 through Rx 300 (non-Tonga/Carrizo/Fiji) GPUs. Instead, they only talk about the AMDGPU kernel driver just for the very newest AMD GPUs like the R9 Fury and Carrizo APUs.
However, AMD said that this is all transitory and Vulkan will eventually become completely open sauce. In fact, AMD has promised to focus more on open-source than closed-source in the future.
The problem is that closed-source software is needed for some workstation features, OpenGL 4.5, and OpenCL.
Basic support for AMD’s closed-source (Catalyst) OpenGL and OpenCL support riding atop the rest of the AMDGPU driver stack is complete. Their initial Vulkan driver is using DRI3.