VK_KHR_ray_tracing_position_fetch returns invalid vertex positions

[LDAP]

The current release of amdvlk announces support for the VK_KHR_ray_tracing_position_fetch Vulkan extension. However, the returned vertices are not (always) valid:

Tested on 6800 XT and 7900 XTX GPUs on Linux. The same application is working on the current mesa drivers and on Intels and Nvidia GPUs.

Reproducible with https://github.com/LDAP/merian-quake
Note that https://github.com/LDAP/merian/blob/main/include/merian/vk/extension/extension_vk_ray_tracing_position_fetch.hpp must be edited to not disable the extension on the AMD Open-source Driver.

[LDAP]

Tested on Windows as well: Driver 25.6.1. Result: One frame of a broken scene, then device lost on the next submit. Works flawlessly with position fetch disabled.