Microsoft Word Hardware Reconfiguration Methodology V final2

System calls

Another type of interdependency is the system call. A system call, according to [4] is an operating system subroutine that provides a uniform manner for performing operating system- level tasks such as deleting files, managing directories, opening hardware for I/O, communicating with the network, etc. A system call relies on pre-existing functions and API’s provided by the kernel. Using system calls a programmer does not have recreate a function or API already provided by the system; furthermore, in all likelihood, the new function would not be as efficiently written. Because the kernel controls the system’s hardware, it makes sense to place low-level functionality into the kernel that can be used by developers and programmers alike. When a low-level task (i.e. routine) is called by an application, it places the system call and passes control to the kernel which then runs the appropriate subroutine (i.e. system call), and once completed, returns control back to the requesting application.

4. Compatibility issues

1. Background

Due to its modular nature the Linux, operating system can be replaced in whole or in pieces. Of course, the issue of software and library interdependencies may need to be resolved when updating or upgrading both software and the operating system.

The openness of Linux makes it possible to see the interdependent nature of applications that rely on various software libraries and the kernel. There are tools that come bundled with most Linux

systems that enable the user to examine the various functions and system calls made by requesting applications for library and/or kernel functionality. These tools can also be used to examine library-based issues (i.e. inconsistencies and incompatibilities) that can arise when they are replaced by newer versions. Sometimes the problem with newer libraries is that older functionality is removed thus causing issues with older dependent applications and libraries; nevertheless, this functionality may still be required by certain applications. Therefore, these various troubleshooting tools can also be used to track down specifics that may be indicative of a potential failure when upgrading libraries and or the kernel.

When upgrading a kernel or software library, it is not always possible to determine the impact that changes to these libraries or kernel may have on the system. This is why it is important to test applications after upgrades.

2.