VMS Software, which acquired the rights to continue the development of the OpenVMS (Virtual Memory System) operating system from Hewlett-Packard five years ago, has released OpenVMS 9.1, noteworthy for its support of the x86-64 architecture. The OpenVMS operating system has been evolving since 1977 and is used in fault-tolerant systems that require high reliability; it was previously only available for VAX, Alpha, and Intel Itanium architectures. Notably, attempts to port OpenVMS to x86 systems in the late 1980s were unsuccessful due to a lack of funding, after which the port's author moved to Microsoft and created Windows NT.
The proposed OpenVMS port for the x86-64 architecture, in addition to installation on real hardware, supports usage in virtual machines KVM, VMware, and VirtualBox. The port is built from the same source code of OpenVMS used in the versions for Alpha and Itanium architectures, utilizing conditional compilation to replace features tied to the specifics of hardware architectures.
The OpenVMS code is adapted for building using LLVM instead of the proprietary GEM compiler used for building the Alpha and Itanium ports (a special translator has been written to reflect GEM IR into LLVM IR, and Clang is adapted to compile C++ code for OpenVMS). UEFI and ACPI are used for identifying and initializing hardware, and a RAM disk is utilized for loading instead of the VMS-specific boot mechanism. To emulate the missing privilege levels of VAX, Alpha, and Itanium absent in x86-64 systems, the OpenVMS kernel employs the SWIS (Software Interrupt Services) module.
Source: opennet.ru
