QNX-Unix Operating System

Thèmes abordés

Unix, Linux, QNX, Operating System, Systèmes d'exploitation, Kernel, Noyau, Process Manager

Résumé du document

QNX was born in 1982, from the hands and the brains of two Waterloo university students Dan Dodge and Gordon Bell. It is a Real Time Operating System.

Elaborated on an UNIX structure, it is used in the software development, the control of industrial robots, and in onboard computers. Stable, ergonomic, safe and fast and is known for its very high uptime, it knows a good fault tolerance. Moreover the preemptive multitasking and the Memory Protection Runtime make it a stable basis for development for many uses.

Extraits

[...] Process Manager As we have seen on the schema the Process Manager works closely with the Microkernel to provide essential operating system services. It manages the creation of new processes and deals with the fundamental resources associated. To launch it, the 3 methods are: Fork that makes ​​an all data copy of the process (norm POSIX). Exec that replaces the process by a new process (norm POSIX). Spawn it is a new process which is the child of the one who created it. It can be any machine on the network. [...]

[...] It is a Real Time Operating System. Elaborated on an UNIX structure, it is used in the software development, the control of industrial robots, and in onboard computers. Stable, ergonomic, safe and fast and is known for its very high uptime, it knows a good fault tolerance. Moreover the preemptive multitasking and the Memory Protection Runtime make it a stable basis for development for many uses. General Structure : the Microkernel - The Key Element Schema 1 QNX uses a microkernel which allows to operate the global system as a set of little tasks, called “servers”. [...]

[...] Developers can query and/or change these parameters by using the adapted utility. Filesystem Manager The Filesystem Manager allows to store and access data on disk subsystems. It responds to the following requests: open, close, read, and write files. QNX implements at least six types of files; five of these are managed by the Filesystem Manager : Regular files (*.txt, *.jpeg ) Directories Symbolic links (contain a pathname to a file or directory that is to be accessed in place of the symbolic link file) FIFOs and Pipes (using during cooperating processes) Block special files (Hard Disk partition ) The Filesystem is a standard one. [...]

[...] Photon This is the microkernel GUI Windowing System of QNX. It is also able to load the different components in plug-ins. Thus, QNX revolves around a Microkernel, four modules and a GUI. This Operating System provides multitasking, priority-driven preemptive scheduling, and fast context switching. It lets us set up our system in order to use just the required resources. Its response time is 0.55 µsec (on a Pentium III) against almost 10ms for Windows NT 4.0 Unfortunately, it is now surpassed by its competitors, especially operating systems with Linux kernel. [...]

[...] Execution The process is ready for execution Termination A process is terminated if: A signal is delivered to the process, or The process invokes exit() At the end of this last step, a termination thread in the Process Manager is run. It runs with the process ID of the terminating process. This thread closes all open file descriptors. Then, notification of process termination is sent to the parent process. Device Manager This module deals with the interface between processes and peripheral terminals. The Device Manager regulates the flow of data between an application and the device. [...]