--- title: A look at Vulkan extensions in Venus | daily.dev description: Venus is a virtual Vulkan driver built on the Virtio-GPU protocol that serializes Vulkan commands between guest and host. The post walks through the three key... canonical: https://daily.dev/posts/a-look-at-vulkan-extensions-in-venus-lp5bkgbhx twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: A look at Vulkan extensions in Venus | daily.dev og:description: Venus is a virtual Vulkan driver built on the Virtio-GPU protocol that serializes Vulkan commands between guest and host. The post walks through the three key... og:url: https://daily.dev/posts/a-look-at-vulkan-extensions-in-venus-lp5bkgbhx og:image: https://api.daily.dev/og/posts/LP5bKgBhX.png og:image:alt: A look at Vulkan extensions in Venus og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # A look at Vulkan extensions in Venus **[Collabora Blog](https://daily.dev/sources/collabora)** · 12 min read · 1 upvotes · 0 comments ## Summary Venus is a virtual Vulkan driver built on the Virtio-GPU protocol that serializes Vulkan commands between guest and host. The post walks through the three key components — the Mesa driver, the Venus Protocol (XML-based spec with code generation), and Virglrenderer — and demonstrates step-by-step how to add support for a new Vulkan extension (VK_EXT_extended_dynamic_state2). This includes updating the protocol XMLs, regenerating serialization code, implementing the guest-side Mesa functions with the vn_ prefix, caching physical device features, enabling passthrough, and adding the host-side Virglrenderer dispatch function. The process is relatively lightweight because Venus-Protocol auto-generates most serialization boilerplate. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does the Venus virtual Vulkan driver serialize commands between guest and host? Venus serializes Vulkan commands using the Venus Protocol, an XML-defined specification that generates C encoder/decoder code for both the Mesa guest driver and Virglrenderer on the host. The guest Mesa driver batches commands into a command stream and sends them via the Virtio-GPU kernel driver. Files prefixed vn_protocol_driver_* serve Mesa; vn_protocol_renderer_* serve Virglrenderer. Return values travel the same path in reverse. _Developers building or debugging virtual GPU stacks track Venus and Virglrenderer developments on daily.dev._ ### What files do I need to modify to add a new Vulkan extension to the Venus driver? Adding a Vulkan extension to Venus requires changes in three places: the Venus Protocol XMLs (add the extension to vk.xml's extension list and new commands to VK_EXT_command_serialization.xml, then regenerate code), the Mesa guest driver under src/virtio/vulkan/ (implement vn_-prefixed functions, update the features cache struct, and add the extension to the passthrough list), and Virglrenderer (enable the extension in vkr_common.c and add vkr_dispatch_ functions for any new commands). _Vulkan driver contributors working across Mesa and Virglrenderer find related patches and discussions on daily.dev._ ### How does Venus handle physical device feature caching for Vulkan extensions? Venus caches physical device features during vkEnumeratePhysicalDevices or vkEnumeratePhysicalDeviceGroups so that later calls like vkGetPhysicalDeviceFeatures2 return cached values without a host round-trip. To support a new extension, you add its feature struct to vn_physical_device_features in vn_physical_device.h, register it with VN_ADD_EXT_TO_PNEXT in vn_physical_device_init_features, and add a case in vn_GetPhysicalDeviceFeatures2 to copy the cached struct back to the caller. _Teams porting Vulkan extensions to virtualized environments keep up with Venus internals on daily.dev._ ## Similar posts on daily.dev - [Flatpak Exploring GPU Virtualization To Ease Driver Challenges](https://daily.dev/posts/flatpak-exploring-gpu-virtualization-to-ease-driver-challenges-0irfkmyja) · Phoronix · 1 upvotes · 0 comments - [Venus Vulkan Driver Lands Mesh Shader Support In Mesa 26.0](https://daily.dev/posts/venus-vulkan-driver-lands-mesh-shader-support-in-mesa-26-0-m4wzjlmka) · Phoronix · 0 upvotes · 0 comments - [Vulkan 1.4.348 Ships Four New Extensions - Including One To Help OpenGL Emulation](https://daily.dev/posts/vulkan-1-4-348-ships-four-new-extensions---including-one-to-help-opengl-emulation-zchboyjvy) · Phoronix · 0 upvotes · 0 comments --- Tags: [#vulkan](https://daily.dev/tags/vulkan), [#mesa](https://daily.dev/tags/mesa) [View this post on daily.dev](https://daily.dev/posts/a-look-at-vulkan-extensions-in-venus-lp5bkgbhx) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"A look at Vulkan extensions in Venus","url":"https://daily.dev/posts/a-look-at-vulkan-extensions-in-venus-lp5bkgbhx","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/a-look-at-vulkan-extensions-in-venus-lp5bkgbhx"},"datePublished":"2026-08-11T08:57:19.518Z","dateModified":"2026-08-11T09:42:11.054Z","description":"Venus is a virtual Vulkan driver built on the Virtio-GPU protocol that serializes Vulkan commands between guest and host. 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Developers building or debugging virtual GPU stacks track Venus and Virglrenderer developments on daily.dev."}},{"@type":"Question","name":"What files do I need to modify to add a new Vulkan extension to the Venus driver?","acceptedAnswer":{"@type":"Answer","text":"Adding a Vulkan extension to Venus requires changes in three places: the Venus Protocol XMLs (add the extension to vk.xml's extension list and new commands to VK_EXT_command_serialization.xml, then regenerate code), the Mesa guest driver under src/virtio/vulkan/ (implement vn_-prefixed functions, update the features cache struct, and add the extension to the passthrough list), and Virglrenderer (enable the extension in vkr_common.c and add vkr_dispatch_ functions for any new commands). 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