Build System

A Cassini distribution can be built by setting the target platform via the MACHINE BitBake variable. In addition, the desired distribution features via the DISTRO_FEATURES BitBake variable. Finally, customizing those features via feature-specific modifiable variables, if needed.

This chapter provides an overview of Cassini’s support for the kas build tool. All the available distribution image features and supported target platforms are defined together with their associated kas configuration files, followed by any other additional customization options. The process for building without kas is then briefly described.

kas Build Tool Support

The kas build tool enables automatic fetch and inclusion of layer sources, as well as parameter and feature specifications for building target images. To enable this, kas configuration files in the YAML format are passed to the tool to provide the necessary definitions.

These kas configuration files are modular, where passing multiple files will result in an image produced with their combined configuration. Further, kas configuration files can extend other kas configuration files, thereby enabling specialized configurations that inherit common configurations.

The kas directory contains kas configuration files that support building images via kas for the Cassini project, and fall into three ordered categories:

  • Base Config

  • Build Modifier Configs

  • Target Platform Configs

To build an Cassini distribution image via kas, it is required to provide the Base Config and one Target Platform Config, unless otherwise stated in their descriptions below. Additional Build Modifier Configs are optional, and depend on the target use-case. Currently, it is necessary that kas configuration files are provided in order: The Base Config and then additional build features via zero or more Build Modifier Configs, and finally the Target Platform Config.

To enable builds for a supported target platform or configure each Cassini distribution image feature, kas configurations files are described in their relevant sections below: Target Platforms and Distribution Image Features, respectively. Example usage of these kas configuration files can be found in the Build and Deploy section of the User Manual.

Note

If a kas configuration file does not set a particular build parameter, the parameter will take its default value.

Target Platforms

Corstone-1000 for MPS3

  • Corresponding value for MACHINE variable: corstone1000-mps3

  • Target Platform Config: kas/corstone1000-mps3.yml

To read documentation about the Corstone-1000, see the Arm Corstone-1000 Technical Overview.

For more information about the software stack for the Corstone-1000, see Arm Corstone-1000 Software.

Corstone-1000 FVP

  • Corresponding value for MACHINE variable: corstone1000-fvp

  • Target Platform Config: kas/corstone1000-fvp.yml

To read documentation about the Corstone-1000 FVP, see the Fast Models Fixed Virtual Platforms (FVP) Reference Guide.

Kria KV260 with U-boot

  • Corresponding value for MACHINE variable: zynqmp-kria-starter-psa

  • Target Platform Config: kas/kv260-psa.yml

This supported target platform is Kria KV260, implemented in meta-trustedsubstrate.

This target uses U-Boot as BL33.

To read the Kria KV260 documentation, see: Kria KV260 User Guide and Kria KV260 Data sheet

Kria KV260 with EDK-II

  • Corresponding value for MACHINE variable: zynqmp-kria-starter-psa

  • Target Platform Config: kas/kv260-edk2.yml

This supported target platform is Kria KV260, implemented in meta-trustedsubstrate.

This target uses EDK-II as BL33.

Generic Arm64

  • Corresponding value for MACHINE variable: genericarm64

  • Target Platform Config: kas/genericarm64.yml

This MACHINE is used to represent a generic 64-bit platform that implements the Arm SystemReady specification, has a working firmware and can boot via EFI.

This machine configuration does not build any firmware components.

All the above include common configuration from kas/include/arm-base.yml which defines layers and dependencies required when building for all Arm-based platforms.

Moreover, corstone1000-fvp.yml, and corstone1000-mps3.yml Target Platform Config include common configuration for Arm-maintained platforms from kas/include/arm-machines.yml which defines the BSPs, layers, and dependencies required when building for each platform.

While kv260-psa.yml and kv260-edk2.yml Target Platform Config include configuration from kas/include/xilinx-machines.yml which defines specific layers and dependencies required when building for this platform.

Distribution Image Features

For a particular target platform, the available Cassini distribution image features (corresponding to the contents of the DISTRO_FEATURES BitBake variable) are detailed in this section, along with any associated kas configuration files, and any associated customization options relevant for that feature.

Cassini Architecture

Cassini distribution image can be configured via kas using Base Config. This includes a set of common configuration from a base Cassini kas configuration file:

  • kas/include/cassini-base.yml

This kas configuration file defines the base Cassini layer dependencies and their software sources, as well as additional build configuration variables. It also includes the kas/include/cassini-release.yml kas configuration file, where the layers dependencies are pinned for any corresponding Cassini release.

  • Corresponding value in DISTRO variable: cassini.

  • Base Config: kas/cassini.yml.

This Cassini distribution image feature enables the cassini-image-base build target, to build an Cassini distribution image.

The Base Config for this distribution image feature sets the build target to cassini-image-base.

To build Cassini distribution image, provide the Base Config to the kas build command. For example, to build a Cassini distribution image for the KV260 hardware target platform, run the following command:

kas build kas/cassini.yml:kas/kv260-psa.yml

Other Cassini Features

Developer Support

  • Corresponding value in DISTRO_FEATURES variable: cassini-dev.

  • Build Modifier Config: kas/dev.yml.

This Cassini distribution feature includes packages appropriate for development, such as the debug-tweaks package (which sets an empty root password) and removing security-hardening features.

kas build kas/cassini.yml:kas/dev.yml:kas/kv260-psa.yml

Run-Time Integration Tests

  • Corresponding value in DISTRO_FEATURES variable: cassini-test.

  • Build Modifier Config: kas/tests.yml.

    This Cassini distribution feature includes the Cassini test suites provided to validate the image is running successfully with the expected Cassini functionalities.

    The Build Modifier for this distribution image feature automatically includes the Yocto Package Test (ptest) framework in the image, configures the inclusion of meta-cassini-tests as a Yocto layer source for the build, and appends the cassini-test feature to DISTRO_FEATURES for the build.

    To include run-time integration tests in a Cassini distribution image, provide the Build Modifier Config to the kas build command. For example, to include the tests in a Cassini distribution image for the KV260 hardware target platform, run the following command:

    kas build kas/cassini.yml:kas/tests.yml:kas/kv260-psa.yml

    The size of the root filesystem is extended via the CASSINI_ROOTFS_EXTRA_SPACE BitBake variable, to 2000000 Kilobytes, which is required by this integration tests if Parsec service is enabled.

    Each suite of run-time integration tests and specific customizable variables associated with each suite are detailed separately, at Run-Time Integration Tests.

Cloud Service

This Cassini distribution feature includes container runtime and orchestration components.

VIRTUAL-RUNTIME_cloud_service is used to select one of three options.

No Cloud

  • Corresponding value in DISTRO_FEATURES variable: cassini-cloud.

  • Corresponding value in VIRTUAL-RUNTIME_cloud_service variable: no-cloud.

  • Build Cloud Configs: kas/no-cloud.yml.

    This Cassini distribution feature provides an image with a default container runtime option (podman) from meta-virtualization without including any cloud provider.

    To build a Cassini distribution image without a cloud provider, provide the Build Cloud Config to the kas build command. For example:

    kas build kas/cassini.yml:kas/no-cloud.yml:kas/kv260-psa.yml
K3s orchestration

  • Corresponding value in DISTRO_FEATURES variable: cassini-cloud.

  • Corresponding value in VIRTUAL-RUNTIME_cloud-service` **variable**: ``k3s-cloud.

  • Build Cloud Configs: N/A (enabled by default).

    This Cassini distribution feature includes the K3s cloud orchestration.

    If Run-Time Integration Tests Build Modifier for this distribution image feature then it will automatically include the required K3s Orchestration Tests test in the ptest framework of the image.

    To include K3s orchestration in a Cassini distribution image, provide the Build Cloud Config to the kas build command. For example:

    The size of the root filesystem is extended via the CASSINI_ROOTFS_EXTRA_SPACE BitBake variable, to 2000000 Kilobytes, which is required by this cloud orchestration.

    kas build kas/cassini.yml:kas/kv260-psa.yml
AWS IoT Greengrass

  • Corresponding value in DISTRO_FEATURES variable: cassini-cloud.

  • Corresponding value in VIRTUAL-RUNTIME_cloud_service variable: greengrass-cloud.

  • Build Cloud Configs: kas/greengrass.yml.

    This Cassini distribution feature includes the AWS IoT Greengrass cloud service.

    To include AWS IoT Greengrass cloud service in a Cassini distribution image, provide the Build Cloud Config to the kas build command. For example:

    The size of the root filesystem is extended via the CASSINI_ROOTFS_EXTRA_SPACE BitBake variable, to 2000000 Kilobytes, which is required by this cloud service.

    kas build kas/cassini.yml:kas/greengrass.yml:kas/kv260-psa.yml

Security Service

This Cassini distribution feature configures parsec-service backend for the Cassini distribution image.

VIRTUAL-RUNTIME_security_provider is used to select one of two options.

PSA Provider

  • Corresponding value in VIRTUAL-RUNTIME_security_provider variable: psa-provider.

  • Build Cloud Configs: kas/psa-security.yml.

    This Cassini distribution feature provides an image with parsec services that uses Trusted-Services as the backend for crypto operations.

    To build a Cassini distribution image with Trusted-Services as the parsec backend, provide the Build Security Provider Config to the kas build command. For example:

    kas build kas/cassini.yml:kas/psa-security.yml:kas/kv260-psa.yml
SW Provider

  • Corresponding value in VIRTUAL-RUNTIME_security_provider variable: sw-provider.

  • Build Cloud Configs: kas/sw-security.yml.

    This Cassini distribution feature provides an image with parsec services that uses Mbed Crypto as the backend for crypto operations.

    To build a Cassini distribution image with Mbed Crypto as the parsec backend, provide the Build Security Provider Config to the kas build command. For example:

    kas build kas/cassini.yml:kas/sw-security.yml:kas/kv260-psa.yml

Parsec service

Corresponding value in DISTRO_FEATURES variable: cassini-parsec.

This Cassini distribution feature adds parsec-service and parsec-tool to the Cassini distribution image.

The value cassini-parsec is appended to DISTRO_FEATURES in meta-cassini-distro/conf/distro/cassini.conf. Therefore, parsec service is included in the Cassini distribution image by default. If parsec-service is not required then the value cassini-parsec can be removed from DISTRO_FEATURES in the <distro name>.conf of the downstream distribution. To build Cassini distribution image with parsec-service for the KV260 hardware target platform, run the following command:

kas build kas/cassini.yml:kas/kv260-psa.yml

Security Hardening

  • Corresponding value in DISTRO_FEATURES variable: cassini-security.

    This Cassini distribution feature configures user accounts, packages, remote access controls and other image features to provide extra security hardening for the Cassini distribution image.

    Security hardening is enabled by default in the Cassini distribution image and the base configuration appends the cassini-security feature to DISTRO_FEATURES for the build. To remove it in the Cassini distribution image, kas/dev.yml can be used. For example:

    kas build kas/cassini.yml:kas/dev.yml:kas/kv260-psa.yml

    The security hardening is described in more detail at Security Hardening.

Additional Distribution Image Customizations

An additional set of customization options are available for Cassini distribution images, which don’t fall under a distinct distribution image feature. These customizations are listed below and are grouped by the customization target.

Filesystem Customization

Adding Extra Rootfs Space

The size of the root filesystem can be extended via the CASSINI_ROOTFS_EXTRA_SPACE BitBake variable. The value of this variable is appended to the IMAGE_ROOTFS_EXTRA_SPACE BitBake variable.

Tuning the Filesystem Compilation

The Cassini filesystem by default uses the generic armv8a-crc tune for aarch64 based target platforms. This reduces build times by increasing the sstate-cache reused between different image types and target platforms. This optimization can be disabled by setting CASSINI_GENERIC_ARM64_FILESYSTEM to "0". The file system compilation tune used when CASSINI_GENERIC_ARM64_FILESYSTEM is enabled can be changed by setting CASSINI_GENERIC_ARM64_DEFAULTTUNE, which configures the DEFAULTTUNE BitBake variable for the aarch64 based target platforms builds. See DEFAULTTUNE for more information.

In summary, the relevant variables and their default values are:

CASSINI_GENERIC_ARM64_FILESYSTEM: "1"             # Enable generic file system (1 or 0).
CASSINI_GENERIC_ARM64_DEFAULTTUNE: "armv8a-crc"   # Value of DEFAULTTUNE if generic file system enabled.

Their values can be set by passing them as environmental variables. For example, the optimization can be disabled using:

CASSINI_GENERIC_ARM64_FILESYSTEM="0" kas build kas/cassini.yml:kas/kv260-psa.yml

Manual BitBake Build Setup

In order to build an Cassini distribution image without the kas build tool directly via BitBake, it is necessary to prepare a BitBake project as follows:

  • Configure dependent Yocto layers in bblayers.conf.

  • Configure the DISTRO as cassini in local.conf.

  • Configure the image DISTRO_FEATURES in local.conf.

Assuming correct environment configuration, the BitBake build can then be run for the desired image target corresponding to one of the following:

  • cassini-image-base

As the kas build configuration files within the kas/ directory define the recommended build settings for each feature. Any additional functionalities may therefore be enabled by reading these configuration files and manually inserting their changes into the BitBake build environment.