Yocto

Prerequisites

sudo apt install gcc g++ \
  python3-distutils python-is-python3

Images

Images are recipes that ultimately inherit from meta/classes/image.bbclass and set the global variable IMAGE_INSTALL, which defines the set of packages (from the package feed area) that will go into the filesystem image. Most images will inherit from meta/classes/core-image.bbclass which inherits directly from image.bbclass, adding to IMAGE_INSTALL packages from the package groups packagegroup-core-boot and packagegroup-base-extended.

Images are defined in recipe files with the file extension 'bb'. In order to separate them from package recipes, there is a convention to put image recipes into a folder named images. Making use of this, we can list all images defined by all layers via

cd poky
ls meta*/recipes*/images/*.bb

Reference images

The following reference images are defined in the meta layer:

	core-image-minimal	small image that just boots the target device
	core-image-minimal-dev	core-image-minimal with headers and libraries allowing development work
	core-image-minimal-initramfs	core-image-minimal with kernel support for in-RAM filesystem
	core-image-base	console-only system fully supporting the target hardware
	core-image-full-cmdline	console-only image that includes many system tools
	core-image-x11	image with basic X11 and a terminal

These image definitions are provided as a starting point for creating project-specific, custom image definitions.

Package Groups

Package groups are recipes that inherit from meta/classes/packagegroup.bbclass and set the content of the global variable PACKAGES. Package groups are defined in recipe files with the file extension 'bb'.

Note that the packagegroup must be inherited before PACKAGES is defined.

inherit packagegroup

PACKAGES = '...'

Using devtool

Use devtool to make changes to an existing recipe and automatically generate an append recipe from those changes.