| #!/usr/bin/env python3 |
| |
| """ |
| Print the vector length in the current context |
| """ |
| |
| import ctypes |
| import sys |
| |
| # These constants must match linux/prctl.h |
| PR_SVE_GET_VL = 51 |
| PR_SVE_VL_LEN_MASK = 0xffff |
| |
| def get_vector_length(): |
| """ |
| Use Prctl(2) to set the process tree's sve vector length. See |
| https://man7.org/linux/man-pages/man2/prctl.2.html for more details |
| """ |
| libc = ctypes.cdll.LoadLibrary('libc.so.6') |
| return_code = libc.prctl( |
| PR_SVE_GET_VL) |
| if return_code < 0: |
| print(f'Failed to get VL, rc: {return_code}') |
| sys.exit(1) |
| print((return_code & PR_SVE_VL_LEN_MASK) * 8) |
| |
| if __name__ == '__main__': |
| if any(arg in ["--help", "-h"] for arg in sys.argv) or len(sys.argv) > 1: |
| print(f"usage: {sys.argv[0]}") |
| print("\nGets the current vector length of this process tree") |
| sys.exit(0) |
| |
| get_vector_length() |
| |
