Function ring_kernel_ptx_template_for 

pub fn ring_kernel_ptx_template_for(major: u32, minor: u32) -> String

PTX kernel source template for persistent ring kernel, generic over the target compute capability (major, minor).

This is a minimal kernel that immediately marks itself as terminated.

PTX .target directives are only forward-compatible (PTX built for sm_X runs on sm_X and newer, never older) — so this must be generated per-device rather than hardcoded to a single value. Maps the device’s actual compute capability to the corresponding PTX ISA version, matching the minimum ISA version that introduced each sm_XX target (per NVIDIA’s PTX ISA documentation).