Mesa Vulkan Drivers Move Ahead With PCI Bus Info, Calibrated Timestamps

Written by Michael Larabel in Mesa on 15 October 2018 at 08:55 PM EDT. Add A Comment
With this weekend's release of Vulkan 1.1.88 stealing the show was the Vulkan transform feedback capability to allow projects like DXVK to support Direct3D's Stream Output functionality. But besides VK_EXT_transform_feedback, there are other extensions also being worked on for Mesa ANV / RADV Vulkan driver coverage.

Two of the other extensions new to Vulkan 1.1.88 and with ANV/RADV driver patches pending are VK_EXT_pci_bus_info and VK_EXT_calibrated_timestamps. The VK_EXT_pci_bus_info extension allows for exposing PCI bus information to the Vulkan game/engine/app users, assuming the GPU is making use of the PCIe bus. RADV has already merged their support into Mesa 18.3. On the Intel side there is a patch that is yet to be merged.

More interesting is the VK_EXT_calibrated_timestamps extension and as of today are now RADV/ANV patches pending. VK_EXT_calibrated_timestamps allows for calibrated timestamps that can span multiple time domains. This should be useful for synchronization in some games but especially virtual reality (VR) use-cases.

Keith Packard who has been working as a Valve contractor on improving the Linux graphics stack for SteamVR was the one writing the Intel ANV and Radeon RADV patches for this calibrated timestamps code. The code is out there but not yet merged. Though ideally there could be some yet-to-happen kernel bits for working to reduce deviation between clock values.

Great to see ANV and RADV keeping up with their timely Vulkan support especially compared to what used to be rather untimely OpenGL open-source driver advances. This latest Vulkan work will be found in Mesa 18.3 due out before year's end.
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