Language Selection

English French German Italian Portuguese Spanish

How System Calls Work in Linux?

Filed under
HowTos

Every GNU/Linux programmer here reading this article must have used system calls to code their programs. GNU/Linux programming is incomplete without system calls. System calls are initiated by software interrupts. Before we delve into that, however, let’s define system calls.

A system call is the mechanism used by an application program to request service from the operating system, or more specifically, the operating system kernel.

Modern processors execute instructions in different privilege states. In system, where just two levels are defined (as in i386), these states are known as user mode and supervisor mode. These privilege levels are defined so that an operating system restrict can control the operations performed by the program. Controlling is done for reasons of security and stability. The kernel of the operating system should always run in privilege mode since it needs to do some operations. Such operations include accessing hardware devices, enabling and disabling interrupts, changing privileged processor state, and accessing memory management units.

Now with this setup of an operating system (with two modes of execution (considering only i386 architecture only)), we need a mechanism to transfer control safety from lesser privileged modes to higher privileged modes.

Full Story.

More in Tux Machines

Android Leftovers

Availability of Qt Free Edition

In my last blog posts, I explained the KDE Free Qt Foundation, which guarantees the free availability of the Qt Toolkit. Today, The Qt Company introduced a new Qt online installer that requires users to accept additional license terms. Many people have contacted me with concerns about this change. I share this concern. Even before this, I have already been concerned about the structure of the qt.io download page, since it blurs the lines between the Qt Toolkit itself and additional, proprietary products. Read more

Valve's Mods Blunder Prompts Reddit Community to Create Open Source Steam Replacement

Valve has recently gone through a major PR debacle after the company announced that it's implementing paid mods for games and Skyrim in particular. Their decision was short-lived, and it was retracted, but they have managed to incur the rage of the community. Independent developers are now working on a new game launcher that will make Steam obsolete. Read more

Biicode goes open source early after outpouring of community support

After the announcement, our community growth skyrocketed. Our investors were so impressed by the welcoming of our open source announcement that they let us go ahead with open sourcing biicode early. We worked hard to release most of it in biicode 3.0. Read more