Setting up a Yocto Build Environment

Initialising the build directory, setting MACHINE in local.conf, listing layers in bblayers.conf and building the first image.

Setting up a Yocto build environment

A typical Yocto project is initialized from a source tree.

After obtaining the appropriate Yocto/OpenEmbedded sources, the environment can be initialized with:

source oe-init-build-env

This command prepares the shell environment and normally creates a build directory.

For example:

build/
├── conf/
│   ├── local.conf
│   └── bblayers.conf

Two files are particularly important.

local.conf contains local build configuration.

For example:

MACHINE = "my-machine"

Other configuration options can control:

For example:

DL_DIR ?= "${TOPDIR}/../downloads"

This can keep downloaded source archives outside the build directory.

bblayers.conf defines which layers are available to BitBake.

Conceptually:

BBLAYERS = " \
    /path/to/meta-layer1 \
    /path/to/meta-layer2 \
    /path/to/meta-custom \
"

If a recipe belongs to a layer that is not included in BBLAYERS, BitBake will not be able to use it.

This is one of the first things to check when BitBake reports that it cannot find a recipe.

Once the environment is configured, we can build an image.

A common minimal image is:

bitbake core-image-minimal

The first build can take a long time.

This is normal.

Yocto may need to:

After the first build, many components are cached, so subsequent builds can be significantly faster.