Table of Contents
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Introduction
This wiki shows how to create a custom layer in an open source Xilinx Yocto flow. After creating the layer, it provides an example of creating your own machine based on a ZCU102 configuration.
Prerequisites
Yocto Supported Linux Distro
- Bare-metal Linux or Virtual Machine
- Yocto Project Documentation
Xilinx Tools Dependencies
Note | ||
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These dependencies are not required for |
- Install
xvfb
(X virtual framebuffer) see UG1144 Table 2-1 - XSDK or XSCT Installation (required for
meta-xilinx-tools
layer)
Xilinx Open Source Yocto Installation
Creating Your Custom Layer
You may create your custom layer manually by copying an existing layer.conf
, however, Yocto provides some helper scripts to automate it. The bitbake-layers create-layer
script will generate a base layer with a default priority of 6. Once the layer is created, you can either add the layer to bblayers.conf
manually or use the bitbake-layers add-layer
to automate it. Note that adding it manually will be faster, but may increase the likelihood of typos or syntax errors. The sequence below is an example of how to apply these scripts. You may cut-and-paste the commands below into a local script to further automate this flow. The resulting layer.conf
and bblayers.conf
are shown below.
Setup the Bitbake
...
environment.
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# From Yocto root directory source setupsdk # Optional: Make a backup copy of Backup local.conf and bblayers.conf cp conf/local.conf conf/local.conf.bk cp conf/bblayers.conf conf/bblayers.conf.bk |
Create
...
your custom layer.
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export LAYER=example cd ..$ROOT/sources/meta-example bitbake-layers create-layer meta-$LAYER cd meta-$LAYER mkdir -p $LAYER/{conf/machine ,recipes-kernel/linux-xlnx ,recipes-bsp/{u-boot/u-boot-xlnx,device-tree/files}} cd $BBPATH bitbake-layers add-layer $LAYER |
Note |
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The environment variable ROOT is set in the "setupsdk" script and is AMD/Xilinx specific. ./sources/meta-$LAYERROOT is not set in the Yocto proper script "oe-init-build-env". |
Custom Layer Directory Structure
After the directory structure is created, you can begin populating the layer with recipes, bbappends, patches, cfg fragments, machine configs, etc. The example.bb
recipe is an artifact of the create-layer
and can be safely deleted. You can continue expanding your layer to include recipes for custom BSPs, applications and other open source components or stacks. At this point, it's pretty straight forward to put your layer under Git control.
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$ tree meta-example meta-example ├── conf │ ├── layer.conf │ └── machine ├── COPYING.MIT ├── README ├── recipes-bsp │ ├── device-tree │ │ └── files │ └── u-boot │ └── u-boot-xlnx ├── recipes-example │ └── example │ └── example.bb └── recipes-kernel └── linux-xlnx |
Warning | |
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layer.conf | In releases |
Verify Your Layer
You can verify that your custom layer has been properly added to the Yocto build system by running bitbake-layers
show-layers
as shown below.
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$ bitbake-layers show-layers | grep meta-example meta-example /home/emil/yocto/sources/meta-example 6 |
Removing Your Layer
To remove a layer, you can either manually edit the bblayers.conf
or use the bitbake-layers remove-layer
script as shown below from the build
directory.
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$ bitbake-layers remove-layer meta-example |
Creating a New Machine Configuration
Now lets create a machine configuration that inherits all of the defaults from the zcu102-zynqmp
machine. The name of this new machine will be the tuple example-zcu102-zynqmp
. In the conf/machine
directory of your custom layer, create a machine configuration file named example-zcu102-zynqmp.conf
with the require
statement below . This will include all of the defaults from the zcu102-zynqmp
. At this point you can customize the machine by adding new properties or overriding any of the zcu102-zynqmp
defaults.
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require conf/machine/zcu102-zynqmp.conf |
Now you can build bitbake your new machine by specifying the MACHINE
variable on the bitbake
command line.
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$ MACHINE=example-zcu102-zynqmp bitbake petalinux-image-minimal |
Related Links
Install and Build with Xilinx Yocto
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Xilinx Yocto Builds without an Internet Connection