ChorusOS 4.0 Introduction

Configuration Options

Configuring a ChorusOS operating system means defining all the components, and their characteristics, which are assembled to form a system image. There are several types of configuration options:

Configuration settings, including the configuration profile definitions are stored in the configuration directory, conf, in your system image build area. The configuration directory is read and updated by both the command-line and graphical configuration tools.

Feature Options

A ChorusOS feature is a boolean variable, whose value determines whether or not a particular component is included in the system image. Setting a feature to true results in code being added to the kernel, providing additional services such as file system handlers, or networking protocols.

Feature options within the ChorusOS operating system are listed in "Operating System Components".

Configuration Profiles

The ChorusOS operating system provides profiles which are used to set up an initial configuration. These profiles include or remove certain features in the system.

Two pre-defined configuration profiles, the basic profile and the extended profile, are provided to help you select an initial configuration for the ChorusOS operating system. The extended profile is the default profile, and does not need to be explicitly specified.

The extended configuration profile corresponds to a reference configuration for telecommunications systems. It includes support for networking using remote IPC over Ethernet and an NFS client. This uses the protected memory model.

The basic configuration profile corresponds to a realistic configuration, keeping the footprint small. With this configuration, applications are usually embedded in the system image and launched either at boot time or subsequently from the image file system or the boot file system. This configuration uses the flat memory model, to minimize the footprint. System administration is local, with C_INIT access through the console.

Table 3-1 shows the settings of all the features in the extended and basic configuration profiles.

Table 3-1 Feature settings in the extended and basic configuration profiles
 Nameextended profile valuebasic profile value
 Kernel features
 C_INIT features
 IOM features
 AM features
 ADMIN features

Note -

The MONITOR feature is an internal feature which is only used by the Java Virtual Machine.

Both configuration profiles include support for system debugging.

You can use one of these configuration profiles as the initial configuration for your system, and add or remove specific feature options using the configurator utility (see "Command-line Configuration Tool"). Once you have created your initial configuration, you can also use the graphical configuration tool ews (see "Graphical Configuration Tool") to manage the configuration.

Tunable Parameters

Tunable parameters are system parameters which affect system behavior and capabilities. They are used to configure the kernel and the included features, to change their behavior, and adapt them to your needs. Typical examples of tunables are: maximum number of kernel objects, scheduler type and attributes for threads, or system clock frequency. Each system component or feature defines a number of these tunable parameters.

Static Parameters

Static parameters are tunable parameters whose values are permanently set within a system image. Changing these values requires rebuilding the system image.

The procedure for assigning new values to tunable parameters is detailed in "Changing Tunable Parameter Values".

Dynamic Parameters

For some tunable parameters, an additional flexibility is offered: the ability to assign values to these parameters at various stages of system production and execution. These types of parameters are called dynamic parameters. These dynamic parameters define the system environment.

Dynamic parameters form a system-wide environment. A basic set of services allows this environment to be constructed and consulted within a system image, at boot time and runtime.

Compared to static parameters, dynamic parameters require additional target data memory in order to store their names and values.

The procedure for modifying dynamic parameters is detailed in "Modifying the System Environment".

System Image Components

The system image contains a configured version of the ChorusOS operating system, and possibly some user-defined applications (actors).

Depending on its configuration options, the ChorusOS operating system is itself built from a kernel and a collection of actors. These actors, which contribute to the implementation of some ChorusOS operating system features, are called ChorusOS operating system actors.

Configuration options concerning the system image components deal mainly with the inclusion of system and application actors within system images.