Yocto cheatsheet

conf/local.conf - frequent configurations

Adding a package (IMAGE_INSTALL):

IMAGE_INSTALL:append = " wireguard-module rsyslog"    # syntax for "Honister" or newer releases
IMAGE_INSTALL_append = " wireguard-module rsyslog"    # syntax for releases older than "Honister"

Configuring the hardware target (MACHINE):
```
MACHINE = "raspberrypi4-64"
```

Adding a rootfs format (IMAGE_FSTYPES):

IMAGE_FSTYPES:append = " hddimg"    # syntax for "Honister" or newer releases
IMAGE_FSTYPES_append = " hddimg"    # syntax for releases older than "Honister"

Don’t fail on dangling *.bbappend files (BB_DANGLINGAPPENDS_WARNONLY):
```
BB_DANGLINGAPPENDS_WARNONLY = "true"
```

Set useful features (EXTRA_IMAGE_FEATURES):

EXTRA_IMAGE_FEATURES = "debug-tweaks ssh-server-dropbear package-management"

Switch the kernel recipe (PREFERRED_PROVIDER, PREFERRED_VERSION):

PREFERRED_PROVIDER_virtual/kernel = "linux-raspberrypi-rt"
PREFERRED_VERSION_virtual/kernel = "4.19.%"

RaspberryPi extra flags (ENABLE_I2C, RPI_EXTRA_CONFIG):

ENABLE_I2C = "1"
RPI_EXTRA_CONFIG:append = "\n \
dtoverlay=i2c-rtc,ds3231 \n \
"    # syntax for "Honister" or newer releases
RPI_EXTRA_CONFIG_append = "\n \
dtoverlay=i2c-rtc,ds3231 \n \
"    # syntax for releases older than "Honister"

Appending to a variable when building for a specific architecture/hardware target:

IMAGE_INSTALL:append:qemuall = " ntpdate "    # syntax for "Honister" or newer releases
IMAGE_INSTALL_append_qemuall = " ntpdate "    # syntax for releases older than "Honister"

Removing from a variable when building for a specific architecture/hardware target:

IMAGE_INSTALL:remove:qemuall = "avrdude"    # syntax for "Honister" or newer releases
IMAGE_INSTALL_remove_qemuall = "avrdude"    # syntax for releases older than "Honister"

Setting the default hostname (reference):

hostname:pn-base-files = "custom hostname"    # syntax for "Honister" or newer releases
hostname_pn-base-files = "custom hostname"    # syntax for releases older than "Honister"

Ignoring some recipes (BBMASK):

BBMASK = "meta-freescale/recipes-kernel/linux"
BBMASK .= "|meta-freescale/recipes-connectivity/openssl"

Blacklisting a package based on name (syntax from Kirkstone):
```
SKIP_RECIPE[busybox] = "Lorem ipsum error message"
```
Blacklisting packages based on license (INCOMPATIBLE_LICENSE):
```
INCOMPATIBLE_LICENSE = "GPL-3.0 LGPL-3.0 AGPL-3.0"
```

Whitelisting packages with commercial license flags (LICENSE_FLAGS_WHITELIST):

LICENSE_FLAGS_WHITELIST = "commercial_ffmpeg commercial_x264" # Honister or older
LICENSE_FLAGS_ACCEPTED = "commercial_ffmpeg commercial_x264" # Kirkstone or newer

conf/local.conf - mirroring & caching

Enabling the low-level.wiki mirrors:

SOURCE_MIRROR_URL = "https://low-level.wiki/large_files/yocto/downloads/"
INHERIT += "own-mirrors"

Setting a pre-mirror server (SOURCE_MIRROR_URL):

SOURCE_MIRROR_URL = "http://.../sources/"
INHERIT += "own-mirrors"

Setting a sstate-mirror server (do not change the PATH - it’s a keyword, SSTATE_MIRRORS):
```
SSTATE_MIRRORS = "file://.* http://.../sstate/PATH"
```
Setting the local DL_DIR (this can be reused across multiple builds or to set up a mirror, DL_DIR, BB_GENERATE_MIRROR_TARBALLS):
```
DL_DIR = "/var/data/downloads"
BB_GENERATE_MIRROR_TARBALLS = "1"
```
Setting the local SSTATE_DIR (this can be reused across multiple builds or to set up a mirror, SSTATE_DIR):
```
SSTATE_DIR = "/var/data/sstate"
```

Other Yocto commands

Search engine for yocto programs, recipes and layers: https://layers.openembedded.org/layerindex/branch/master/recipes/.
Run kernel menuconfig (you have to save and copy the generated config file afterwards):
```
bitbake -c menuconfig virtual/kernel
```
Clean the environment for a recipe:
```
bitbake -c cleanall avrdude
```

Download all the prerequisites for a build:

bitbake core-image-minimal --runall=fetch

Find out which recipe is responsible for a file in the final image:
```
oe-pkgdata-util find-path /bin/sh
```
Find out which recipe is responsible for a package:
```
oe-pkgdata-util lookup-recipe python3-io
```
Find out information (recipe name, version) about a package:
```
oe-pkgdata-util package-info acl
```
Find out the value of some variables from a recipe:
```
oe-pkgdata-util read-value RDEPENDS acl
```
Start a docker container with the container’s directory /home mapped over the physical directory /mnt/ssd/rpi-tutorial-2/. This is useful if you’re recreating old yocto buils, and the host OS is newer (and incompatible). The re-mapping is specified, in case the default docker filesystem is placed on a HDD, but you also have an SSD installed.
```
sudo docker run -it --mount type=bind,source=/mnt/ssd/rpi-tutorial-2/,target=/home ubuntu:16.04
```

Using generated images

Run image in qemu (without root permissions or graphical interface, after the yocto environment has been “sourced”, check the README). Only works if the board has an acompanying *.qemuboot.conf file:
```
runqemu nographic slirp
```

Copy the generated image for RaspberryPi on sdcard:

sudo apt-get install bmap-tools
sudo bmaptool copy core-image-minimal-raspberrypi4-64.wic.bz2 /dev/mmcblk0

Converting from “hddimg” image to “vdi” (loadable into virtualbox):

"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" convertdd core-image-minimal.hddimg  new_file.vdi --format VDI

Converting from “vmdk” image to raw “hddimg” (writable on a disk):

vboxmanage clonemedium disk ubuntu-cosmic-18.10-cloudimg.vmdk --format RAW pm-vm-physical-1.0.img

Using “templateconf”