SYS$ - SYS$ Interface Routines

Overview

VX/SYS$ is a call-compatible implementation of the OpenVMS SYS$ system services for x86 and ARM Linux. It lets migrated OpenVMS applications perform system-level work such as device and resource management, process creation and control, event flags and locks, logical names, timers, privilege checks, and interprocess communication, while preserving the exact call signatures and VMS condition codes the original code depends on. VX/SYS$ is delivered inside VX/RT and links straight into the recompiled program, so there is no system-service process to install or administer.

Each service is written once as an inner worker and exported under its OpenVMS names through linker aliases, so recompiled C, Fortran, and COBOL programs call the same routines, pass the same arguments, and read back the same status values as they did on VMS. The SYS$ module itself provides more than 110 system-service entry points; together with the RMS file services and lock-manager services linked from the same runtime, an application sees the full OpenVMS SYS$ callable surface of over 150 routines. Services with no equivalent on a host operating system are documented plainly, so migration planners know exactly where behaviour differs.