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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.
Releases Supported
Xilinx Yocto rel-v2018.1
and later (Rocko 2.4)
Prerequisites
Yocto Supported Linux Distro
- Dedicated or virtual Linux machineBare-metal Linux or Virtual Machine
- Yocto Project Reference Manual: Supported Linux DistributionsDocumentation
Xilinx Tools Dependencies
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Note |
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These dependencies are not required for rel-v2018.3 |
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- 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
Info |
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Don't forget to edit the path and version variables in local.conf to point to the current SDK root directory. |
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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language | bash |
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theme | Midnight |
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title | Create Yocto Layer |
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| export LAYER=example # your layer name goes here
# From Yocto root directory
Setup Bitbake Environment |
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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
# Add a default MACHINE in local.conf or specify on the command line for bitbake, e.g. MACHINE=zcu102-zynqmp
echo 'MACHINE ?= "zcu102-zynqmp"' >> conf/local.conf
# Create your layer in the sources directory
cd ../sources |
Create your custom layer.
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language | bash |
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theme | Midnight |
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title | Create Custom Yocto Layer |
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LAYER=$ROOT/sources/meta-example
bitbake-layers create-layer meta-$LAYER
# Create
custom layer directory structure for Xilinx components
mkdir -p $LAYER/{conf/machine ,recipes-kernel/linux-xlnx ,recipes-bsp/{u-boot/u-boot-xlnx recipes-bsp/,device-tree/files \
recipes-bsp/hdf/files recipes-bsp/fsbl/files recipes-bsp/pmu-firmware/files
# Add new layer with }}
bitbake-layers or edit bblayers.conf manually
cd ../build
bitbake-layers add-layer ../sources/meta-$LAYER
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Warning |
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In releases rel-v2018.1 and rel-v2018.2 , edit conf/layer.conf . If there is a double backward slash “\\” in the BBFILES variable, delete one backward slash, so there is only a single backward slash “\” . This is required for proper line continuation, otherwise your bbappend files will not be found. |
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language | bash |
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theme | Midnight |
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title | layer.conf |
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# We have a conf and classes directory, add to BBPATH
BBPATH .= ":${LAYERDIR}"
# We have recipes-* directories, add to BBFILES
BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
${LAYERDIR}/recipes-*/*/*.bbappend"
BBFILE_COLLECTIONS += "meta-example"
BBFILE_PATTERN_meta-example = "^${LAYERDIR}/"
BBFILE_PRIORITY_meta-example = "6" |
Code Block |
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language | bash |
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theme | Midnight |
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title | bblayers.conf |
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LCONF_VERSION = "7"
BBPATH = "${TOPDIR}"
BBFILES ?= ""
BBLAYERS ?= " \
/home/emil/yocto/sources/core/meta \
/home/emil/yocto/sources/core/meta-poky \
<...>
/home/emil/yocto/sources/core/../meta-xilinx/meta-xilinx-bsp \
/home/emil/yocto/sources/core/../meta-xilinx/meta-xilinx-contrib \
/home/emil/yocto/sources/core/../meta-xilinx-tools \
/home/emil/yocto/sources/core/../meta-petalinux \
/home/emil/yocto/sources/core/../meta-virtualization \
/home/emil/yocto/sources/core/../meta-openamp \
/home/emil/yocto/sources/meta-example \
"
BBLAYERS_NON_REMOVABLE ?= " \
/home/emil/yocto/sources/core/meta \
" |
Note |
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The environment variable ROOT is defined in the "setupsdk" script. ROOT is not defined in the Yocto proper "oe-init-build-env" script. |
Custom Layer Directory Structure
After the directory structure is created, you can begin populating the layer with recipes, bbappends, patches, cfg fragments, machine configs, etc. The example.bb
recipe is an artifact of the create-layer
and can be safely deleted. You can continue expanding your layer to include recipes for custom BSPs, applications and other open source components or stacks. At this point, it's pretty straight forward to put your layer under Git control.
Code Block |
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language | bash |
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theme | Midnight |
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title | meta-example |
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$ tree meta-example
meta-example
├── conf
│ ├── layer.conf
│ └── machine
├── COPYING.MIT
├── README
├── recipes-bsp
│ ├── device-tree
│ │ └── files
│ ├── fsbl
│ │ └── files
│ ├── hdf
│
│ └── files
│ ├── pmu-firmware
│ │ └── files
│ └── u-boot
│ └── u-boot-xlnx
├── recipes-example
│ └── example
│ └── example.bb
└── recipes-kernel
└── linux-xlnx
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Warning |
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In releases rel-v2018.1 and rel-v2018.2 , you may need to edit conf/layer.conf . If there is a double backward slash “\\” in the BBFILES variable, delete one backward slash, so there is only a single backward slash “\” . This is required for proper line continuation, otherwise your bbappend files will not be found. |
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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language | bash |
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theme | Midnight |
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title | show-layers |
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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.
Code Block |
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language | bash |
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theme | Midnight |
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title | remove-layer |
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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.
Code Block |
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language | bash |
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theme | Midnight |
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title | conf/machine/example-zcu102-zynqmp.conf |
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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.
Code Block |
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language | bash |
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theme | Midnight |
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title | bitbake |
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$ MACHINE=example-zcu102-zynqmp bitbake petalinux-image-minimal |
Info |
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Make sure you have sourced setupsdk and you are in the build directory when baking. |
Related Links
Install and Build with Xilinx Yocto
Adding an HDF a Hardware Platform to a Xilinx Yocto Layer
Customizing Device Trees in Xilinx Yocto
Xilinx Yocto Builds without an Internet Connection
References
Yocto Project Mega-Manual (2.4.4)Documentation