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Adding a new machine to Yocto involves the following:

Create a new layer which will hold all the recipes and machine configurations for the new SoC/OEM

yocto-layer command is not enabled by default,  If you want to add a new layer using the "yocto-layer" script, you need to first download the poky and put it in your code base and run the script to create a new folder.

You can download poky from git using :               

Use the yocto-layer create sub-command to create a new general layer.

$ yocto-layer create mylayer <specify the layer which you need to be created>

Eg :

Please enter the layer priority you'd like to use for the layer: [default: 6] 6
Would you like to have an example recipe created? (y/n) [default: n] n
Would you like to have an example bbappend file created? (y/n) [default: n] n
New layer created in meta-new-layer.

There shall be separate device (machine) configuration file (.conf) for each device for the particular chip family for which the layer is intended for.

For Eg : A layer "meta-rdk-oem-OEM-X-SOC-Y" means this layer shall be able to build any devices manufactured by  OEM "X" with all variants of SoC "Y" like Y-1,Y-2 etc

The device (machine) configuration file shall include corresponding include (.inc) file to get machine configuration details.

Adding the Machine Configuration File for the new SoC/OEM

To add a machine configuration, you need to add a .conf file with details of the device being added to the conf/machine/ file.

The most important variables to set in this file are as follows:

• TARGET_ARCH (e.g. "arm")
• PREFERRED_PROVIDER_virtual/kernel (see below)
• MACHINE_FEATURES

You might also need these variables:

• KERNEL_IMAGETYPE (e.g. "zImage")
• IMAGE_FSTYPES (e.g. "tar.gz")
• The default configuration is defined in meta-rdk/conf/distro/rdk.conf and it should be overwritten by the machine specific conf file.

Adding a Kernel for the Machine

The OpenEmbedded build system needs to be able to build a kernel for the machine. We need to either create a new kernel recipe for this machine, or extend an existing recipe.We can find several kernel examples in the source

The directory at meta/recipes-kernel/linux that you can use as references. If you are creating a new recipe, following steps need to be done,

• Setting up a SRC_URI.
• Specify any necessary patches
• Create a configure task that configures the unpacked kernel with a defconfig.

If you are extending an existing kernel, it is usually a matter of adding a suitable defconfig file. The file needs to be added into a location similar to defconfig files used for other machines in a given kernel.

A possible way to do this is by listing the file in the SRC_URI and adding the machine to the expression in COMPATIBLE_MACHINE:

• COMPATIBLE_MACHINE = '(qemux86|qemumips)'

Adding Recipe for SoC/OEM

The following kind of recipes can be added to SoC/OEM layer. The recipes shall be grouped as described in slide “BSP Reference Layer”

• recipes (.bb) to build Kernel
• recipes(.bb)  to build SDK
• Kernel patches (SoC/OEM specific - if any)
• SDK patches (SoC/OEM specific - if any)
• Any SoC/OEM specific scripts or files which need to be installed in RF

Creating packages for building images 

Create a custom packagegroup package group for the SoC/OEM which shall list all the recipes that are required for this image.

For example, the following recipe can be appended to the broadband package group.

Create a custom image for required SoC/OEM. For example:

Adding your own custom layer

Use the yocto-layer create sub-command to create a new layer.

Add this to ./meta-rdk/conf/bblayers.conf.sample.

Recipes can be placed inside recipes-< > folders. There can be a configuration file inside conf/ for layer specific configuration and classes folder for keeping information that is useful to share between metadata files.