Overview: Einit and init.yaml

Einit initializing program

When a solution is started, the KasperskyOS kernel finds the executable file named Einit (initializing program) in the solution image and runs this executable file. The initializing program performs the following operations:

• Creates and starts processes when a solution is started.
• Creates IPC channels between processes when a solution is started (statically creates IPC channels).

A process of the initializing program belongs to the Einit class.

Generating the source code of the initializing program

The KasperskyOS SDK includes the einit tool, which generates the C-language source code of the initializing program. The standard way to use the einit tool is to integrate an einit call into one of the steps of the build script, which generates the einit.c file containing the source code of the initializing program. In one of the following steps of the build script, you must compile the einit.c file into the executable file of Einit and include it into the solution image.

You are not required to create formal specification files for the initializing program. These files are provided in the KasperskyOS SDK and are automatically applied during a solution build. However, the Einit process class must be specified in the security.psl file.

The einit tool generates the source code of the initializing program based on the init description, which consists of a text file that is usually named init.yaml.

Syntax of init.yaml

An init description contains data in YAML format. This data identifies the following:

• Processes that are started when the solution starts.
• IPC channels that are created when the solution starts and are used by processes to interact with each other (not with the kernel).

This data consists of a dictionary with the entities key containing a list of dictionaries of processes. Process dictionary keys are presented in the table below.

Process dictionary keys in an init description

Key	Required	Value
name	Yes	Process class name (from the EDL description).
task	No	Process name. If this name is not specified, the process class name will be used. Each process must have a unique name. You can start multiple processes of the same class if they have different names.
path	No	Name of the executable file in ROMFS (in the solution image). If this name is not specified, the process class name (without prefixes and dots) will be used. For example, processes of the Client and net.Client classes for which an executable file name is not specified will be started from the Client file. You can start multiple processes from the same executable file.
connections	No	Process IPC channel dictionaries list. This list defines the statically created IPC channels whose client IPC handles will be owned by the process. The list is empty by default. (In addition to statically created IPC channels, processes can also use dynamically created IPC channels.)
args	No	List of program startup parameters (main() function parameters). The maximum size of one item on the list is 1024 bytes.
env	No	Dictionary of program environment variables. The keys in this dictionary are the names of environment variables. The maximum size of an environment variable value is 1024 bytes.

Process IPC channel dictionary keys are presented in the table below.

IPC channel dictionary keys in an init description

Key	Required	Value
id	Yes	IPC channel name, which can be defined as a specific value or as a link such as {var: <constant name>, include: <path to header file>}.
target	Yes	Name of the process that will own the server handle of the IPC channel.

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