On Unix-like systems, this is accomplished with the system call.

Both processes return from the system call and execute the next instruction.

The system call is capable of directing signals either to individual processes or to process groups.

User space programs could create threads through a system call.

If the system call cannot complete before the access, then it must be restartable.

All are really the same thing, a system call to the hypervisor below.

Those traits include code, data, system call and other common software characteristics.

Many system calls are provided to applications, to allow them to access all those services.

Essentially calls are made within programs and a checked copy of the request is passed through the system call.

However system calls are typically exposed as C library functions.