Summary

A. Device Runtime Support
The Runtime support and Environment variable for Device offloading in OpenMP include:

Runtime support routines

- void omp_set_default_device(int dev_num)
- void omp_get_default_device(void)
- void omp_get_num_device(void)
- void omp_get_num_teams(void)
- void omp_get_team_num(void)
- void omp_is_initial_device(void)

Environment variable

-control default device through OMP_DEAFAULT_DEVICE which should be
B. What is new in OpenMP 4.5?
- Unstructured data mapping by adding enter and exit clauses to Target data map.
- Asynchronous execution by adding nowait and dep clauses in Target construct.
- New Device Memory API routines.
- Supports for device pointers.
- New Combined constructs.
- Efficient global mapping for variables by using declare target link.