HelenOS

The microkernel handles multitasking, memory management and inter-process communication. It also provides kernel-based threads and supports symmetric multiprocessing.

Typical to microkernel design, file systems, networking, device drivers and graphical user interface are isolated from each other into a collection of user space components that communicate via a message bus.

Each process (called task) can contain several threads (preemptively scheduled by the kernel) which, in turn, can contain several fibers scheduled cooperatively in user space. Device and file-system drivers, as well as other system services, are implemented by a collection of user-space tasks (servers), creating thus the multiserver nature of HelenOS.

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.

HelenOS development is community-driven. The developer community consists of a small core team, mainly staff and former and contemporary students of the Faculty of Mathematics and Physics at Charles University in Prague, and a number of contributors around the world.{{Cite web |url=http://www.ohloh.net/p/helenos/contributors |title=HelenOS Contributors measured by Ohloh |access-date=2012-03-15 |archive-date=2010-04-12 |archive-url=https://web.archive.org/web/20100412002404/http://www.ohloh.net/p/helenos/contributors |url-status=dead }} In 2011, 2012 and 2014, HelenOS participated in the Google Summer of Code as a mentoring organization.[http://www.google-melange.com/gsoc/projects/list/google/gsoc2011 List of projects accepted into Google Summer of Code 2011][http://www.google-melange.com/gsoc/projects/list/google/gsoc2012 List of projects accepted into Google Summer of Code 2012][http://www.google-melange.com/gsoc/projects/list/google/gsoc2014 List of projects accepted into Google Summer of Code 2014] In 2013, the project was a mentoring organization in the ESA Summer of Code in Space 2013 program.{{Cite web |url=http://sophia.estec.esa.int/socis2013/?q=node%2F13 |title=Selected mentoring organizations |access-date=2020-01-11 |archive-url=https://web.archive.org/web/20170716044813/http://sophia.estec.esa.int/socis2013/?q=node%2F13 |archive-date=2017-07-16 |url-status=dead }}

The source code of HelenOS is published under the BSD-3-Clause license, while some third-party components are available under the GNU General Public License.{{Cite web |url=http://www.ohloh.net/p/helenos/analyses/latest |title=HelenOS analysis by Ohloh |access-date=2012-03-15 |archive-date=2011-04-01 |archive-url=https://web.archive.org/web/20110401225643/http://www.ohloh.net/p/helenos/analyses/latest |url-status=dead }} Both of these licences are free software licenses, making HelenOS free software.

HelenOS runs on several different CPU architectures including ARM, x86-64, IA-32, IA-64 (Itanium), MIPS, PowerPC (32-bit only), SPARC V9 and RISC-V.{{Citation|last=FOSDEM|title=Lessons learned from porting HelenOS to RISC-V Pros and cons of RISC-V from a microkernel OS point …|date=2019-02-11|url=https://www.youtube.com/watch?v=evnahBRjwKQ |archive-url=https://ghostarchive.org/varchive/youtube/20211222/evnahBRjwKQ |archive-date=2021-12-22 |url-status=live|access-date=2019-02-25}}{{cbignore}} At some point in time{{explain|date=January 2019}}, various versions of HelenOS ran on real hardware from each architecture (as opposed to running only in a simulator of that architecture).

HelenOS supports PATA, SATA, USB mass storage, USB HID, an Atheros USB WiFi dongle, several Ethernet network cards, SoundBlaster 16 and Intel HDA audio devices, serial ports, keyboards, mice and framebuffers.

HelenOS is being used for research[http://www.isvav.cz/researchPlanDetail.do?rowId=MSM0021620838 Institutional research plan MSM0021620838 - Modern methods, structures and systems of computer science (2005-2011, MSM)][http://d3s.mff.cuni.cz/research/ Research @ D3S] in the area of software components and verification by the Department of Distributed and Dependable Systems, Charles University, Prague. Besides that, HelenOS has been used by students as a platform for software projects and master theses.[http://is.cuni.cz/eng/studium/dipl_st/index.php?fak=11320&fulltext=HelenOS&fulltext_kde%5b%5d=nazev&fulltext_kde%5b%5d=ostatni&full_or_like=1&kterep=obh&f=find&do=main&f=Search Defended HelenOS theses at Faculty of Mathematics and Physics, Charles University in Prague]{{Dead link|date=January 2020 |bot=InternetArchiveBot |fix-attempted=yes }}

{{Reflist}}

{{Portal|Free and open-source software}}

• [http://www.helenos.org HelenOS home page]
• [http://www.helenos.org/documentation HelenOS theses, papers and documentation.]
• [https://github.com/HelenOS/helenos HelenOS] on GitHub

{{Microkernel}}

{{Hobbyist operating systems}}

Category:Free software operating systems

Category:Microkernel-based operating systems

Category:ARM operating systems

Category:MIPS operating systems

Category:IA-32 operating systems

Category:X86-64 operating systems

Category:Microkernels

Category:Software using the BSD license

Category:Hobbyist operating systems