Surprisingly, the NT kernel implements a copy-on-write fork function - the Windows subsystem does not allow Windows applications to use that function, though. B

Surprisingly, the NT kernel implements a copy-on-write fork function - the Windows subsystem does not allow Windows applications to use that function, though. Bash for Windows is implemented as a separate subsystem from Windows on top of the NT kernel, allowing it to build its own abstractions on top of the kernel.