HelenOS
OS family | Experimental |
---|---|
Working state | Current |
Source model | Open Source |
Latest release | 0.4.0 / Feb 14 2009 |
Repository | |
Platforms | IA-32, AMD64, SPARC V9, IA-64, PowerPC, ARM, MIPS |
Kernel type | Microkernel |
License | BSD |
Official website | www.helenos.org |
HelenOS is an operating system based on a preemptible microkernel design. The source code of HelenOS is published under free software licences, making the operating system free software.
Technical Overview
HelenOS is based on a preemptible microkernel called SPARTAN. The microkernel handles multitasking, memory management and inter-process communication. It also provides kernel-based threads and supports symmetric multiprocessing. Each process (called task) can contain several threads (preemptively scheduled by the kernel) which, in turn, can contain several fibrils scheduled cooperatively in user space. Device and file-system drivers, as well as other system services, are implemented in user-space tasks (servers).
Tasks communicate via HelenOS IPC, which is connection-oriented and asynchronous. It can be used to send small fixed-size messages, blocks of bytes or to negotiate sharing of memory. Messages can be forwarded without copying bulk data or mapping memory to the address space of middle-men tasks.
Development
HelenOS is partly hobbyist, partly academic, being developed mainly by staff and former and contemporary students of the Faculty of Mathematics and Physics at Charles University in Prague, with help from other contributors around the world.
Available ports
HelenOS has been ported to run on many different computer architectures including ARM, AMD64 (x86-64), IA-32, IA-64 (Itanium), MIPS, PowerPC (32-bit only), and SPARC V9. There are also incomplete ports to 64-bit PowerPC and the Xen hypervisor paravirtualization environment on IA-32.
Source-code licensing
The source code of HelenOS is published under the BSD licence, while some third-party components are available under the GNU General Public License, and others are public domain. Both of these licences are free software licences, making HelenOS free software.
Research use
HelenOS is used for research in the area of creating a fully componentized operating system and implementing an object-oriented filesystem.