VMS Software, which bought the rights to continue developing the OpenVMS (Virtual Memory System) operating system from Hewlett-Packard five years ago, has published the release of OpenVMS 9.1, notable for the implementation of support for the x86-64 architecture. The OpenVMS operating system has been in development since 1977, is used in fault-tolerant systems that require increased reliability, and was previously only available for the VAX, Alpha and Intel Itanium architectures. It is noteworthy that attempts to port OpenVMS to x86 systems in the late 1980s were unsuccessful due to the termination of funding, after which the author of the port moved to Microsoft and created Windows NT.
The proposed OpenVMS port for the x86-64 architecture, in addition to being installed on real hardware, supports the use in KVM, VMware and VirtualBox virtual machines. The port is built from the same OpenVMS sources used in the Alpha and Itanium versions, using conditional compilation to replace features tied to hardware architectures.
The OpenVMS code has been adapted for building using LLVM instead of the proprietary GEM compiler used to build the Alpha and Itanium ports (a special compiler has been written that reflects GEM IR in LLVM IR, and Clang has been adapted to build C++ code for OpenVMS). UEFI and ACPI are used for hardware detection and initialization, and a RAM disk is used for booting instead of a hardware-specific VMS boot mechanism. To emulate the missing VAX, Alpha and Itanium privilege levels that are missing in x86-64 systems, the SWIS (Software Interrupt Services) module is used in the OpenVMS kernel.
Source: opennet.ru