irisandClaude Opus 5
b9924e7617
`mask_sdf` SIGSEGVd after printing `test result: ok`, and the workaround was to hand the device to the process with `mem::forget` on the reading that "dropping a wgpu device on Venus segfaults". Every part of that except the symptom was wrong. `rigs/gpu-probe`'s new `teardown` bin is the experiment, one variable per mode: the same open-and-close exits 0 on the main thread and SIGSEGVs on a spawned one; it needs no GPU work and no device, only an instance; raw `ash` does it with no wgpu involved at all; and keeping the instance alive fixes it. Destroying the last VkInstance makes the loader dlclose the ICD, and Mesa's ICD here registers a pthread_key_create destructor into its own text without `-z nodelete`, so glibc calls it through unmapped memory when the thread exits. libtest runs every #[test] on a spawned thread, which is the whole reason this looked like a drop bug. `VK_LOADER_DISABLE_DYNAMIC_LIBRARY_UNLOADING=1` confirms the mechanism. So the fix is one `wgpu::Instance` for the process -- what wgpu asks for anyway -- and the device, queue and everything else drop normally again. The escape and its paragraph of reasons are gone. Also: the machine-level graphics notes duplicated in docs/RUST.md, run-headless.sh and two source comments now point at the `this-machine-graphics` skill, which is the only copy. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>