The GIET_VM is a static operating system for shared address space, many-cores architectures. These architectures are generally NUMA (Non Uniform memory Acces), because the memory is logically shared, but physically distributed, and the main goal of the GIET_VM is to address these NUMA issues.

The GIET_VM assumes that the hardware architecture is structured as a 2D mesh of clusters. There is one physical memory bank, and several processor cores per cluster. Each processor is identified by a composite index [x,y,p] where x, y are the cluster coordinates, and p is the local processor index.

The GIET_VM is written for the MIPS32 processor. The virtual addresses are on 32 bits and use the (unsigned int) type. The physical addresses can have up to 40 bits, and use the (unsigned long long) type.

The GIET_VM supports a paged virtual memory, with two types of pages BPP (Big Physical Pages: 2 Mbytes), and SPP (Small Physical Pages: 4 Kbytes). The physical memory allocation is fully static: all page tables (one page table per virtual space) are completely build and initialized in the boot phase. There is no page fault, and no swap on disk in the GIET_VM.

The GIET_VM supports parallel multi-tasks user applications. A GIET_VM user application is similar to a POSIX process: one virtual space per application. A task is similar to a Posix thread: all tasks in a given application share the same virtual space. Any task can be allocated to any processor, but the allocation is fully static : no task migration.

When there is more than one task allocated to a processor, the scheduling is pre-emptive, and uses a periodic TICK interrupt. It implements a round-robin policy between all runnable tasks.There is one private scheduler for each processor.

The GIET_VM supports generic architectures: The hardware parameter values (such as the number of clusters, or the number of cores per cluster) are defined in the hard_config.h file.

The GIET-VM configuration parameters (such as the TICK period, or the max number of open files) are defined in the giet_config.h file.