Extending the Linux microPlatform

Adding Packages to the Image

The meta-subscriber-overrides.git repo allows you to customize the packages included in your factory image. To do this, you add packages as a list to the variable CORE_IMAGE_BASE_INSTALL in recipes-samples/images/lmp-factory-image.bb. For a quick example let us add the stress-ng utility package to the build:

git clone https://source.foundries.io/factories/<myfactory>/meta-subscriber-overrides.git
vi meta-subscriber-overrides/recipes-samples/images/lmp-factory-image.bb

Add “stress-ng” to the package list:

vim \
stress-ng \
...

Then:

git add meta-subscriber-overrides/recipes-samples/images/lmp-factory-image.bb
git commit -m "add stress-ng package to device image"
git push

Go and get a coffee—your Factory is generating a new image with this package. This can take a half an hour or more.

You can check the status at:

https://ci.foundries.io/projects/<myfactory>/lmp/

Once completed and the update is applied, the device will reboot. This behavior is customizable; you can apply rules to determine when devices should restart. Once restarted, the stress-ng command will be available.

List of Available Recipes

OE provides a tool to search layers and recipes. Remember to set the same branch name used by the current factory version.

Creating a Python3 Package from PyPi

Some Python packages do not yet have a recipe for python3 in OE. If this is the case with a desired package, use the template below to add a new package from PyPi.

Create a recipe in the meta-subscriber-overrides.git repository using the following naming scheme:

recipes-devtools/python/python3-<package name>_<version>.bb

(E.g.: recipes-devtools/python/python3-virtualenv_16.4.3.bb)

Example file contents:

DESCRIPTION = "Virtual Python Environment builder"
HOMEPAGE = "https://pypi.python.org/pypi/virtualenv"
SECTION = "devel/python"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://LICENSE.txt;md5=51910050bd6ad04a50033f3e15d6ce43"

SRC_URI[md5sum] = "5f012791118fe99990d9422cf560edf3"
SRC_URI[sha256sum] = "984d7e607b0a5d1329425dd8845bd971b957424b5ba664729fab51ab8c11bc39"

inherit setuptools pypi

DEPENDS += " \
      python3-pip \
      "

RDEPENDS:${PN} += " \
      python3-dateutil \
      "

Using the information and packages from the PyPi website, fill in the details about the new Python package

Fig. 38 Pypi package

Update the following variables to reflect the details for the package you wish to create a recipe for.

DESCRIPTION
HOMEPAGE
LICENSE
LIC_FILES_CHKSUM
SRC_URI[md5sum] (md5sum of the download artifact from pypi)
SRC_URI[sha256sum] (sha256sum of the download artifact from pypi)
DEPENDS Dependencies resolved at do_configure
RDEPENDS Dependencies resolved at do_build

Using `FEATURES` to Configure LmP

Three “features” variables control and configure the build system: DISTRO_FEATURES, IMAGE_FEATURES and MACHINE_FEATURES. Each one takes effect in a single aspect of the build system.

Important

When changing DISTRO_FEATURES, the distro changes. This results in the rebuilding of packages, which can take a while.

When changing MACHINE_FEATURES, the hardware description changes. This results in a different group of packages installing to the image.

When changing IMAGE_FEATURES, the image changes. This may reflect in the list of packages installed, or in the image configuration.

Make sure you understand the result of any change.

DISTRO_FEATURES is a list of configurations from a distro that reflects how some packages build or install. While there is a list of Yocto Project distro features supported, the list can expand by including other meta layers. For example, the distro features systemd or wayland define the list of packages to install, and configures how some packages build. The distro feature modsign,along with certificates, signs the kernel modules.

The default value used by LmP is defined in meta-lmp/meta-lmp-base/conf/distro/include/lmp.inc. This can be customized by architecture, machine, or any other override. To customize, use DISTRO_FEATURES:append = <value> to add a feature, and DISTRO_FEATURES:remove = <value> to remove one. To remove a feature from an override list, use DISTRO_FEATURES:remove:<machine> = <value>.

Use the command bitbake-getvar to see the value of some variables, and all the intermediate values:

$ bitbake-getvar DISTRO_FEATURES
NOTE: Starting bitbake server...
#
# $DISTRO_FEATURES [7 operations]
#   :append /lmp/source/main/build-lmp/conf/../../layers/meta-lmp/meta-lmp-base/conf/distro/include/lmp.inc:40
#     " pam usrmerge virtualization ptest alsa"
#   :append /lmp/source/main/build-lmp/conf/../../layers/meta-lmp/meta-lmp-base/conf/distro/lmp.conf:18
#     " sota"
#   set? /lmp/source/main/build-lmp/conf/../../layers/openembedded-core/meta/conf/distro/include/default-distrovars.inc:20
#     "${DISTRO_FEATURES_DEFAULT}"
#   :append /lmp/source/main/build-lmp/conf/../../layers/openembedded-core/meta/conf/distro/include/init-manager-systemd.inc:2
#     " systemd"
#   set /lmp/source/main/build-lmp/conf/../../layers/openembedded-core/meta/conf/documentation.conf:144
#     [doc] "The features enabled for the distribution."
#   set? /lmp/source/main/build-lmp/conf/../../layers/openembedded-core/meta/conf/bitbake.conf:884
#     ""
#   :append[tegra] /lmp/source/main/build-lmp/conf/../../layers/meta-lmp/meta-lmp-bsp/conf/machine/include/lmp-machine-custom.inc:690
#     " opengl"
# pre-expansion value:
#   "${DISTRO_FEATURES_DEFAULT} pam usrmerge virtualization ptest alsa sota systemd"
DISTRO_FEATURES="acl argp bluetooth ext2 ipv4 ipv6 largefile usbgadget usbhost wifi xattr zeroconf pci vfat modsign efi security tpm integrity seccomp pam usrmerge virtualization ptest
alsa sota systemd"

Using DISTRO="lmp" generates the log. DISTRO_FEATURES can be changed by seven operations, and one of them is for an override (tegra). The log also shows file path and line for each operation.

The line starting with DISTRO_FEATURES= show the variable value.

The Yocto Project also provides IMAGE_FEATURES and MACHINE_FEATURES. These are lists of features for the image and to describe the machine, respectively. There is also lists of Yocto Project image features and Yocto Project machine features supported by the project.

The LmP uses the MACHINE_FEATURES for a machine to determine if a package gets included. For example, the OP-Tee package is only included in an image if the target machine includes the feature optee within MACHINE_FEATURES.

Including Private Git+ssh Repositories

Custom recipes may need access to private Git repositories only available via SSH. The ci-scripts repo has logic to handle this when a Factory has secrets created using a simple naming convention.

Secrets matching the pattern ssh-*.key are loaded into an ssh-agent, and ssh-known_hosts is used to sets the trusted host keys for the Git server(s).

To generate ssh-known_hosts:

$ ssh-keyscan github.com > /tmp/ssh-known_hosts

An example for accessing a private GitHub repo:

$ fioctl secrets update ssh-github.key==/tmp/ssh-github.key
$ fioctl secrets update ssh-known_hosts==/tmp/ssh-known_hosts

At this point new CI jobs will be able to access recipes that have SRC_URI items like:

SRC_URI = "git://[email protected]/<repo>;protocol=ssh;branch=main"