On Linux the ONNX Runtime WebGPU execution provider runs on Dawn with the Vulkan backend, and Mesa lavapipe is a CPU-based Vulkan adapter that Dawn treats like any device. The skill explains why that is enough for correctness checks: many host-side validation paths, such as shape and broadcast enforcement, fire before any shader is dispatched, and element-wise and broadcasting kernels run correctly if slowly. It covers installing `mesa-vulkan-drivers` and `vulkan-loader` with `dnf` on Azure Linux, the `--use_webgpu` build flag, the `onnxruntime_provider_test` target and `VK_ICD_FILENAMES`.
The scope is strict: lavapipe validates host-side enforce and shape bugs and MatMul-free kernels only. Any graph containing a MatMul, including the expanded Attention node tests, crashes lavapipe's LLVM JIT, and for those macOS arm64 Metal is the source of truth. The skill says never to treat a green lavapipe run as validating an Attention or MatMul fix, and it is not a substitute for a real GPU on performance-sensitive paths. The excerpt is truncated.