VC5 Gallium3D: A New Broadcom Open-Source Driver
VC5 currently consists of a new Gallium3D driver while Anholt will also begin developing a new DRM/KMS driver for the mainline Linux kernel. You may recall the VC4 driver work led by Anholt that is notably used for Raspberry Pi boards with Broadcom SoCs while the VC5 driver is for a new generation of Broadcom graphics.
VC5 currently targets the new BCM7268 SoC, which features the new V3D3.3 graphics processor. Not many details are available on the Broadcom V3D3.3 but it is capable of OpenGL ES 3.1 and it looks like we may end up seeing a Vulkan driver too worked on by Anholt, judging from some of his code remarks.
The BCM7268 SoC is marketed for set-top-box devices and -- excitingly -- will be booting an upstream Linux kernel. The Broadcom SoC support is already part of the mainline Linux kernel while this open-source graphics driver support is still in its early stages.
VC5 has a measurably different instruction set compared to VC4, at the moment there are many similarities between these drivers, and the driver is still a ways off from being conformant. Eric Anholt is hoping to merge the VC5 driver into mainline Mesa not too far out, but keep it disabled by default and hidden until it's in better shape and the adjoining kernel driver has been fully developed.
More details on VC5 via this Mesa-dev post.