tree: 00ac585815eac9455a787da03e1b6169b976f746 [path history] [tgz]
  4. build/
  5. meta/

How to vary a core realm

Note: for a more in-depth explanation, see RFC-0089.

The core realm is the highest-level CFv2 component realm holding other packaged components. The contents of this realm may vary across products, as certain parts of our platform belongs in certain configurations and not in others.

The exact contents of the core realm are controlled by a GN argument that is set in the product definitions (located in //products). This argument contains a list of GN targets. These targets are walked at GN metadata time to find CML shard files to be merged with a common base to create the core realm.

The core's base

The common portions of the core realm which are shared across all products are included in //src/sys/core/meta/core.cml.

Any components or capability routes included in this file will be part of all Fuchsia products. Core shard operations are only additive. Therefore if a new product is added which wishes to exclude a portion of this file, the to-be-excluded contents should be removed from this file and added to a new core shard.

The core shards

The optional portions of the core realm are included in separate CML files, and are pointed to by the core_shard template defined in //src/sys/core/build/core_shard.gni.

Any product wishing to merge a shard into its core realm should include the shard‘s GN target in the core_realm_shards argument in the product’s .gni file.

The core name

Each product which uses the core_realm_shards argument should set a unique value for the core_realm_package_name. This value is used for the name of the generated core realm's package, so that the core realm packages between different products can be disambiguated.

By convention, this value should be set to core-$PRODUCT_NAME. So for example the workstation product's core package name is core-workstation.