Purpose

This Specification defines the role, lifecycle, and fundamental responsibilities of axisd, the PID 1 process and system manager of an Axis-based Operating System.

axisd establishes and manages the Base OS runtime after Boot transfers execution to /sbin/axisd.

Scope

This Specification defines the role of axisd within the Base OS, its relationship to Boot and the Platform, its lifetime as PID 1, and the responsibilities delegated to its child Specifications.

This Specification does not define Platform-specific early boot behavior, the internal implementation of axisd, or the detailed mechanisms used to initialize, manage, observe, or modify individual system resources.

Role

axisd is the system manager of an Axis-based Operating System and MUST execute as PID 1 throughout the Base OS runtime.

axisd is responsible for establishing the runtime environment required by the Operating System and coordinating the management of the running system.

Responsibilities that require more specific behavior or independently refinable abstractions are defined by child Specifications.


flowchart TD
    Boot["Platform boot environment"]
    Axisd["axisd"]
    Runtime["Base OS runtime"]

    Boot -->|executes /sbin/axisd as PID 1| Axisd
    Axisd -->|establishes and manages| Runtime

    class Axisd program

Lifecycle

The lifecycle of axisd begins when the Platform boot environment transfers execution to /sbin/axisd according to the Base OS Boot contract.

axisd MUST begin execution as PID 1. If Platform early userspace previously occupied PID 1, execution MUST be transferred by replacing that process rather than by starting axisd as a child process.

After starting, axisd performs system initialization and then remains active as the system manager for the lifetime of the Base OS runtime.

The lifecycle of axisd ends when the running system shuts down, restarts, or otherwise leaves the Base OS runtime.

Initialization Boundary

Boot is responsible for establishing the OS Artifact as the root filesystem and transferring execution to axisd.

axisd is responsible for all Base OS initialization that occurs after this transition.

Platform-specific work required before the OS Artifact becomes the root filesystem belongs to the Platform boot environment and is outside the responsibility of axisd.


flowchart TB
    Platform["Platform boot environment"]
    Root["OS Artifact as /"]
    Axisd["axisd"]
    Initialization["Base OS initialization"]
    Runtime["Runtime operation"]

    Platform -->|establishes| Root
    Root -->|provides /sbin/axisd| Axisd
    Platform -->|transfers PID 1 to| Axisd
    Axisd --> Initialization
    Initialization --> Runtime

    class Axisd program

Platform Relationship

axisd MUST NOT depend on the identity or implementation details of a particular compatible Platform.

A Platform MAY provide Platform-specific runtime support required to operate the system on its Devices. axisd MAY interact with such support through interfaces defined by the applicable Platform Specifications.

Platform-specific runtime support remains part of the Platform and does not become part of the OS Artifact or axisd.

System Management

After initialization, axisd coordinates the lifecycle and management of the running system.

The specific resources managed by axisd, the operations available to clients, the representation of mutable system state, and the mechanisms used to perform system changes are defined by child Specifications.

This Specification does not require any particular internal architecture, concurrency model, persistence mechanism, or communication protocol.

Fundamental Invariants

axisd is PID 1. axisd MUST execute as PID 1 throughout the Base OS runtime.
axisd begins after Boot. Platform-specific work required to establish the OS Artifact as the root filesystem occurs before responsibility is transferred to axisd.
axisd owns Base OS initialization. Initialization performed after the Base OS root filesystem is established is managed by axisd according to its child Specifications.
axisd remains active during runtime. After initialization, axisd continues operating as the system manager until the Base OS runtime ends.
axisd is Platform-independent. Platform-specific mechanisms MUST be provided through Platform-defined support rather than being embedded into axisd solely for a particular Platform.
Implementation details are not part of the contract unless specified. The internal architecture of axisd MAY evolve without affecting conformance when its externally observable behavior remains compatible with the applicable Specifications.

Conformance

An implementation of axisd conforms to this Specification when it begins execution as PID 1 according to the Base OS Boot contract, establishes and manages the Base OS runtime according to the applicable child Specifications, remains active for the lifetime of that runtime, and satisfies the invariants defined by this Specification.

Child Specifications

Initialization (1.2.1)