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.. _comp_doc_os:

Operating Systems
=================

.. toctree::
   :maxdepth: 2
   :hidden:

   onboarding/index
   community/index
   functional/index
   certifiable/index

An operating system is an environment on which S-CORE is integrated and executed.

In the context of the OS module, **S-CORE acts as the platform integrator**:
S-CORE maintainers integrate and validate specific OS environments as S-CORE
reference platforms and document the practical usage for downstream users.

Operating Systems are categorized into the following **levels**:

* **Community Level**: integrated on a best-effort basis. S-CORE provides **no guarantees**
  that the platform builds or runs reliably.
* **Functional Level**: S-CORE provides **functional guarantees** (build + tests for the
  reference integration).
* **Certifiable Level**: S-CORE provides **certifiability-oriented guarantees** for the
  reference integration and documents additional safety/security expectations.

The concrete level requirements are defined in :ref:`platform_assumptions`.

Roles and responsibilities
--------------------------

Platform integrations follow the process requirements defined in:
:ref:`platform_assumptions`.

Two roles from the process requirements are relevant:

* **Supplier**: provides an external SW element (e.g. OS / hypervisor) that S-CORE uses.
* **System Integrator**: integrates the S-CORE SW-platform into a system.

In the S-CORE Software Platforms, these roles map to:

* **Platform Maintainer** (Supplier role): resolves the *supplier* requirements.
  The platform maintainer provides the prerequisites so that the platform can be considered
  for promotion to a level.

* **S-CORE** (System Integrator role): resolves the *system integrator* requirements.
  Once S-CORE accepts a platform at **Functional** or **Certifiable** level, S-CORE
  must ensure that the accepted guarantees remain valid across all increments.