To create our custom layer, we can use two different methods:

To gain flexibility and avoid mishandling, we'll use the second option. To use it,  we must initially source all variables to gain access through our shell in the yocto-layer script, as shown in the following command:

$ source oe-init-build-env rpi-build

Now that our environment is set up, we have access  to the yocto-layer  script,  and so,  we can begin the process of creating the layer.

Note that this script (yocto-layer) creates the layer in the current directory by default. That is why we must place it at the root of our environment:

$ cd /where/you/want/to/stored/your/layer

We can now launch the script using the following command:

$ yocto-layer create <layer_name> -o <dest_dir>

For our example, we will call our layer meta-packt_rpi. Here is the command:

$ yocto-layer create packt_rpi
Please enter the layer priority you'd like to use for the layer: [default: 6]
Would you like to have an example recipe created? (y/n) [default: n]  y
Please enter the name you'd like to use for your example recipe: [default: example] example-packt
Would you like to have an example bbappend file created? (y/n)  [default: n] y
Please enter the name you'd like to use for your bbappend file:  [default: example] example-packt
Please enter the version number you'd like to use for your bbappend  file (this should match the recipe you're appending to): [default: 0.1]
New layer created in meta-packt_rpi.
Don't forget to add it to your BBLAYERS (for details see meta- packt_rpiREADME).

We have, through this script, generated our own layer, meta-packt_rpi , and inside this layer is a sample recipe, an example of bbappend file, and so on. An example of our generated layer is shown in the following command:

$ tree meta-packt_rpi/
meta-packt_rpi/
├── conf
│ └── layer.conf
├── COPYING.MIT
├── README
├── recipes-example
│ └── example
│ ├── example-packt-0.1
│ │ ├── example.patch
│ │ └── helloworld.c
│ └── example-packt_0.1.bb
└── recipes-example-bbappend
└── example-bbappend
├── example-packt-0.1
│ └── example.patch
└── example-packt_0.1.bbappend

If we want to install our layer, we just have to integrate the absolute path inside the bblayers.conf file, as it says in the README file:

I. Adding the packt_rpi layer to your build 
================================================= 
In order to use this layer, you need to make the build system aware  of it. 
 
Assuming the packt_rpi layer exists at the top-level of your 
yocto build tree, you can add it to the build system by adding the 
location of the packt_rpi layer to bblayers.conf, along with any 
other layers needed. e.g.: 
 
  BBLAYERS ?= "  
    /path/to/yocto/meta  
    /path/to/yocto/meta-yocto  
    /path/to/yocto/meta-yocto-bsp  
    /path/to/yocto/meta-packt_rpi  
    " 

We can add our layer to our bblayers.conf file:

# LAYER_CONF_VERSION is increased each time  build/conf/bblayers.conf 
# changes incompatibly 
LCONF_VERSION = "6" 
BBPATH = "${TOPDIR}" 
BBFILES ?= "" 
BBLAYERS ?= "  
/home/packt/RASPBERRYPI/poky/meta  
/home/packt/RASPBERRYPI/poky/meta-yocto  
/home/packt/RASPBERRYPI/poky/meta-yocto-bsp  
/home/packt/RASPBERRYPI/poky/meta-raspberrypi  
/home/packt/RASPBERRYPI/poky/meta-openembedded/meta-webserver  
/home/packt/RASPBERRYPI/poky/meta-packt_rpi " 
BBLAYERS_NON_REMOVABLE ?= "  
/home/packt/RASPBERRYPI/poky/meta  
/home/packt/RASPBERRYPI/poky/meta-yocto  

After this, our layer is fully integrated with the Yocto Project, and so, it can be parsed by BitBake (the meta scheduler).