hotplugd

hotplugd is the hardware hotplug mediation daemon for EriX.

EriX is a clean-room, capability-based microkernel operating system written entirely in Rust.

Technical requirements are tracked in the EriX requirements, conventions, and project documentation.

See:

• docs for design documents, specifications, and development plans.
• Related architecture repositories for kernel, services, libraries, drivers, and integration tooling.

Purpose of This Repository

This repository implements the EriX hotplug service daemon. Its purpose in EriX is to provide the hotplug service role through explicit IPC and startup authority.

Functionally, it implements the daemon runtime, state model, IPC handling, and validation tests. The repository keeps the implementation, interface contracts, tests, and documentation for that behavior in one reviewable ownership boundary.

The maintained responsibilities are:

• implement the hotplug service runtime and state model
• validate startup authority before accepting IPC requests
• handle bounded service operations through the assigned endpoint set
• keep service behavior, tests, and authority invariants documented

Clean-Room Policy

EriX follows a strict clean-room philosophy:

• No external source code may be copied.
• No external Rust crates are allowed.
• No code generation tools that embed third-party code.
• All code must be authored within the project.

Violations will result in rejection of the contribution.

License

All EriX repositories are licensed under the ISC License.

Development Model

EriX development is modular, deterministic, reproducible, authority-explicit, security-first, and self-hosting oriented.

This repository follows the project roadmap and the validation rules documented in its own roadmap.

Build

cargo build --all-targets --all-features

Test

cargo test --all-targets --all-features
cargo clippy --all-targets --all-features -- -D warnings

Build and Test Modes

This repository supports additive runtime and integration feature gates.

• *-runtime and *-runtime-phase* features select production bootstrap/runtime behavior.
• *-integration-smoke remains available for synthetic end-to-end validation paths.
• *-integration-force-fail remains test-only and MUST NOT be enabled for runtime appliance builds.

Compatibility aliases are kept so existing scenario feature names continue to compile while the runtime naming becomes canonical.

Validation Note

The host/test QUERY_CAP fallback remains cfg-scoped so runtime/release builds stay warning-free.

Dynamic Boot Artifact Evidence

Phase 5.4.37 documents hotplugd as a dynamic boot artifact. The image build packages the hotplug service daemon as an ELF64 x86_64 ET_DYN executable with .erix_dynlink metadata in the signed dynlink-store and mirrors it under /lib/erix/dynlink with its required shared objects.

Startup remains rootd through procd staged dynamic creation before dynlinkd; authority remains the dedicated hotplug endpoint and startup peers. Dynamic packaging and filesystem mirror records are evidence and launch inputs only; they do not grant filesystem, loader, object-store, service-discovery, provider-bypass, block-device, or dynlinkd authority. hotplugd receives only the documented startup endpoints, peers, and capabilities for its role.

Governance Principles

hotplugd governance is scoped to hotplug event coordination.

The scoped governance rules are:

• It processes only explicit hotplug events from authorized sources.
• It coordinates with device-management policy without owning driver launch authority.
• It keeps event handling bounded and deterministic.
• It rejects malformed or unauthorized hotplug notifications.

Authority Boundaries

• hotplugd operates only through startup-assigned service capabilities.
• New authority must be represented in bootstrap/capability validation and integration tests before use.

Contact

Development occurs in EriX organization and discussions happen in issues and design documents.

No decisions are considered valid without documented rationale.

Maintainers can be reached via email: admin@erikinkinen.fi.