Bug#1081314: nvidia-vulkan-icd: Recommends on -rtcore should be a Depends

[Simon McVittie]

Package: nvidia-vulkan-icd
Severity: important

nvidia-vulkan-icd currently Recommends libnvidia-rtcore on the
architectures where it exists.

According to Nvidia developers who I spoke to during my work on the Steam
Runtime, the 64-bit Vulkan driver is not meant to be run in production
without libnvidia-rtcore: even if some basic functionality might work
without it, that setup isn't tested or supported. They say that a
Recommends is not really strong enough here, and it should be a Depends.

https://github.com/ValveSoftware/Dota-2/issues/2787 is an example of a
game that does not work correctly (at least on newer GPUs) without
libnvidia-rtcore being installed.

Thanks,
    smcv