Usage Guide

Classes

An overview of the bitbake classes provided by meta-epics.

epics-component

This class defines the tasks necessary to configure, build and install packages built using the EPICS build system. EPICS modules and IOCs should prefer the epics-module class, which automatically depends on epics-base.

This class also handles generating the configure/RELEASE.local and configure/CONFIG_SITE.local files, which contain build settings and a list of EPICS dependencies.

EPICS dependencies should be provided in the EPICS_DEPENDS variable and are automatically placed into configure/RELEASE.local. To generate the variable names, the class crawls over the strings in EPICS_DEPENDS, strips the epics- and slac-epics- prefixes, converts dashes to underscores, and uppercases the name. So, epics-autosave and epics-my-module become AUTOSAVE and MY_MODULE respectively.

Dependencies must also appear in the Yocto DEPENDS variable to get pulled into the recipe’s sysroot.

By default, packages are only compiled for the target architecture. If the package contains binaries for the host architecture that are needed to build for cross compile targets, set ENABLE_HOST_PACKAGE=1.

A summary of all configuration options for epics-component derived classes can be found below:

Variable	Description
`ENABLE_HOST_PACKAGE`	Flag indicating whether to build for $EPICS_HOST_ARCH. Default: 0
`EPICS_DEPENDS`	List of strings defining the list of EPICS dependencies. Default: “”
`EPICS_ENABLE_SHARED_LIBS`	Enable shared libraries for this package. Useful if you need dynamic loading for something (i.e. pcaspy) Default: 0
`EPICS_ENABLE_STATIC_LIBS`	Enable shared libraries for this package. This is enabled by default, and generally IOCs should be fully statically linked. This can be enabled at the same time as `EPICS_ENABLE_SHARED_LIBS`. Default: 1
`MODNAME`	Defines the module name, which determines how it’s installed under `/opt/epics`. Default: “${PN}”

epics-module

Inherits: epics-component

This class automatically depends on epics-base and epics-base-native, and sanitizes installed *.local and envPaths files.

Recipes for EPICS modules should inherit this class.

epics-ioc-systemd

Inherits: epics-module

EPICS IOCs that are to be deployed on the target using systemd should inherit this bbclass.

This class will automatically install and enable a systemd unit that runs the IOC using procServ. The IOC’s shell will be accessible locally using telnet on the port set in PS_PORT.

Refer to the below table for a list of variables that can be used to control the behavior of this class:

Variable	Description
`PS_PORT`	Port to run procServ on. Default: 30000
`IOC_APP_NAME`	Name of the IOC application. If not provided, the systemd unit relies on the shebang line of the st.cmd to be configured properly.
`IOC_PATH`	Path to the IOC, relative to the root of the app. For example: `iocBoot/ioc-my-test`
`IOC_ST_CMD`	Name of the st.cmd file within `IOC_PATH`. Default: st.cmd
`IOC_ENV`	List of additional variables to append to the envPaths for this IOC. These variables will be expanded with the suffix of `_ENV` when `envPaths` is generated. For example: IOC_ENV += “PV_PREFIX” PV_PREFIX_ENV = “SOME:DEVICE:” The above code will emit `epicsEnvSet("PV_PREFIX", "SOME:DEVICE:")` into the `envPaths`. This provides a mechanism to pass additional configuration data to the IOC without patches.

Python Infrastructure

The python library under python/epics contains some helper functions for interacting with EPICS. This library is used by the epics-component bbclass (and others) to configure EPICS packages for build.

Library components are available under the epics package. No imports are necessary.

`target_arch(d) -> str`

Returns the EPICS target architecture for the target. The target architecture can be determined with linux-${TARGET_ARCH} in a non-Python recipe.

Example: linux-aarch64 for an ARM64 target board.

`host_arch(d) -> str`

Returns the EPICS host architecture. The host architecture can be determined with linux-${BUILD_ARCH} in a non-Python recipe.

Example: linux-x86_64 for a x86_64 build host.

`generate_config_site(d, extra: dict = {})`

Generates configure/CONFIG_SITE.local, configure/CONFIG_SITE.Common.${EPICS_TARGET_ARCH} and configure/CONFIG_SITE.Common.${EPICS_HOST_ARCH} for the package. These files are critical for the cross build to succeed.

extra is a dict of additional key-value pairs to emit into CONFIG_SITE.local

Example:

epics.generate_config_site(d, {"MYVAR": "YES"})

`generate_release_local(d, extra: dict = {})`

Generates configure/RELEASE.local for this package containing a list of dependencies and their paths within the sysroot.

This will overwrite any existing RELEASE.local files that may be in the repository already.

extra is a dict of additional key-value pairs to emit into RELEASE.local