Use Cases

OCA Harness provides a reusable foundation for secure chiplet initialization, including boot sequencing, authentication, firmware loading, and the establishment of a trusted execution context before application logic is released.

The SEP ROM BL0 image uses non-volatile public keys to conduct authentication verification on loaded BL1 software images, and feature control tied to the authentication result ensures the chain of trust cannot be bypassed. Device attestation is also supported by recording the boot process and device configuration and performing attestation using public key infrastructure.

This is one of the most important adoption use cases for OCA Harness because secure boot is required in nearly every deployable chiplet system, yet it is also one of the most repetitive and integration-sensitive pieces of infrastructure.

OCA Harness supports the non-application control functions needed to bring a chiplet or multi-chiplet package into operation and keep it there. This includes initialization of platform resources, configuration of management interconnects, power and reset coordination, telemetry collection, lifecycle control, and the handling of service operations that must exist regardless of the application implemented on top of the chiplet.

Runtime voltage rail management is achieved by communicating with Voltage Regulators via the standard PMBus and AVSBus protocols, while Performance State (P-State) management employs distributed sensors and firmware to enforce power and thermal constraints through mechanisms such as dynamic frequency scaling (DFS) and dynamic voltage and frequency scaling (DVFS).

Fuse-based on-chip storage provides configuration values for SRAM repair, sensor trimming, and fabric setup, with the SMC responsible for fuse sensing and distribution.

A central OCA Harness use case is to let adopters integrate application chiplets into an OCA-based system without having to build all surrounding framework logic themselves. By providing common infrastructure for management, security, debug, and communication, OCA Harness reduces the amount of custom glue logic needed at integration time and makes it easier to combine chiplets from different teams or vendors within a consistent system architecture.

Inter-chiplet coordination relies on standard protocols and transport mechanisms mandated by OCA, including OCCP as the protocol for early-stage boot image and configuration delivery, over I3C/I2C as the auxiliary transport.

In many chiplet systems, not every chiplet owns an independent external boot source or complete standalone management stack. OCA Harness enables a system-level model in which one chiplet or management endpoint can provision firmware, coordinate initialization, and establish runtime policy across other chiplets.

This makes OCA Harness especially useful in asymmetric systems where different chiplets have different boot roles, capabilities, and trust responsibilities.

OCA Harness provides a physically isolated execution environment for cryptographic operations through the SEP subsystem. Secure key services, hardware-accelerated symmetric and asymmetric cryptography, and a True Random Number Generator (TRNG) are available to both SEP firmware and the rest of the system.

User authentication is another service the framework offers: the authentication result can be tied to the secret key derivation so that bypassing authentication renders the system unusable. These capabilities allow adopters to build security features on top of OCA Harness without provisioning their own cryptographic infrastructure.

OCA Harness is also intended to support the practical needs of development and production beyond nominal runtime operation. Common debug and test access, manufacturing-oriented initialization flows, and service interfaces for fault handling and recovery are all use cases that benefit from a shared framework.

Chiplet status reporting is provided through a dedicated UART-based log engine: internally generated log information from different in-package agents is forwarded to the primary SMC and sent out via its UART port. Providing these mechanisms as part of OCA Harness improves consistency across chiplets and reduces the effort needed to make a design usable in validation, bring-up, and field support.

Beyond any single chiplet implementation, OCA Harness serves as a reference framework for organizations adopting OCA. It gives designers a concrete starting point for how boot, security, management, and interoperability infrastructure can be realized in practice, which lowers the barrier to entry for new participants and accelerates ecosystem convergence around common implementation patterns.