Function register 

pub fn register<T: Copy>(
    ptr: *mut T,
    len: usize,
    flags: RegisterFlags,
) -> CudaResult<RegisteredMemory<T>>

Registers an existing host memory range with the CUDA driver for DMA.

Safety contract (upheld by the caller)

• ptr must point to a valid allocation of at least len * size_of::<T>() bytes.
• The allocation must remain valid for the lifetime of the returned handle.

Errors

• CudaError::InvalidValue if len is zero or the byte size overflows.
• CudaError::NotSupported on macOS.
• Other driver errors from cuMemHostRegister_v2.