This page is intended to be a collection place for tips and tricks related to Yocto layers and how Yocto works under Petalinux.

Documentation

The first place you should start to better understand many details of the Yocto project is the Yocto project website.

Working with a User Space Yocto Layer

This tip has been adapted to PetaLinux using the meta-example layer available here meta-example

Installing the meta-example layer on your host

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$ git clone https://github.com/DynamicDevices/meta-example

About the meta-example layer

This example layer is providing 3 build recipes, bbexample, bbexample-rt and bbexample-lt respectively fetching the source code from a git tree, a remote tar file and a local tar file

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$ petalinux-build -c bbexample
$ petalinux-build -c bbexample-rt
$ petalinux-build -c bbexample-lt

Configuring the layer path in the PetaLinux build system

Move to your PetaLinux project build directory, edit the conf/bblayers.conf file and add your layer path to BBLAYERS

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BBLAYERS := " \
  ${SDKBASEMETAPATH}/layers/poky/meta \
  ${SDKBASEMETAPATH}/layers/poky/meta-poky \
  /absolute_path_to_meta_layer/meta-example \
  "

Building the meta-layer example package based on a local source archive

The recipe we are going to build is https://github.com/DynamicDevices/meta-example/blob/master/recipes-example/bbexample/bbexample-lt_1.0.bb

The recipe bbexample-lt is using some variables

1. SRC_URI Space-delimited list of URIs to download source code, patches, and other files from git, local absolute path, https, ftp etc.
2. PN is the Package Name. The value of this variable is derived by BitBake from the base name of the recipe file.
3. PV is the Package Version. which is derived by BitBake from the base name of the recipe file

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# Use local tarball
SRC_URI = "file://bbexample-${PV}.tar.gz"

The recipe bbexample-lt can invoked using the following command

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$ petalinux-build -c bbexample-lt

here is the command output

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$ petalinux-build -c bbexample-lt
 
[INFO] building bbexample-lt
[INFO] sourcing bitbake
INFO: bitbake bbexample-lt
Loading cache: 100% |###############################################################################################################################################################################| ETA:  00:00:00
Loaded 2941 entries from dependency cache.
Parsing recipes: 100% |#############################################################################################################################################################################| Time: 00:00:01
Parsing of 2328 .bb files complete (2294 cached, 34 parsed). 2943 targets, 196 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies
NOTE: Preparing RunQueue
NOTE: Checking sstate mirror object availability (for 38 objects)
NOTE: Executing SetScene Tasks
NOTE: Executing RunQueue Tasks
NOTE: Tasks Summary: Attempted 872 tasks of which 857 didn't need to be rerun and all succeeded.
INFO: Copying Images from deploy to images
[INFO] successfully built bbexample-lt

You have now successfully built the layer but you still need to include the binary produced into the kernel root file system

Including the meta-layer example build output in the Linux root file system

There are two options in order to do so

1. Edit your project conf/local.conf and add

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IMAGE_INSTALL_append = " bbexample-lt"

2. Adding a package to an image via a .bbappend

You may wish to add specific packages to specific images, which is generally viewed as better practice. We are using core-image-minimal bitbake recipe for this tip by creating file core-image-minimal.bbappend. This .bbappend file is extending the original core-image-minimal recipe in order to include the layer build output into the Linux root file system.

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recipes-core/images/core-image-minimal.bbappend

core-image-minimal.bbappend file content

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IMAGE_INSTALL += " bbexample-lt"

Running the meta-layer example under QEMU

1. Rebuild your layer

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$ petalinux-build -c bbexample_lt -x cleansstate

2. Rebuild your kernel

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$ petalinux-build -c kernel

3. Start qemu

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$ petalinux-boot --qemu --kernel

4. Log on qemu and start the application

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root@plnx_arm:/# /usr/bin/bbexample
Hello Yocto World...
Hello World (from a shared library!)

Patching the Linux Kernel of a PetaLinux Project

1. Copy the patch to project file <plnx-proj-root>/project-spec/meta-user/recipes-kernel/linux/linux-xlnx directory.

2. Modify project file <plnx-proj-root>/project-spec/meta-user/recipes-kernel/linux/linux-xlnx_%.bbappend to use the patch file by adding the patch file name to the SRC_URI_append variable. If the variable does not exist in the file then add a new line with

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SRC_URI_append = " file://0001-linux-driver-fix.patch"
 
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

3. Make sure the priority for the meta-user layer is 7 in the project file <plnx-proj-root>/project-spec/meta-user/conf/layer.conf .

Note: Any patches in the project will not be applied to an external source tree for the Linux kernel or u-boot. The user should apply patches to the external source tree.

How to Modify inittab or getty in a PetaLinux Project

1. Create a sysvinit directory in meta-user layer as

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$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/sysvinit/sysvinit-inittab

2. Create a sysvinit-inittab_%.bbappend file and your own inittab file or your inittab patch

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$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/sysvinit/sysvinit-inittab_%.bbappend

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SRC_URI_append = " file://inittab"
 
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

Or

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SRC_URI_append = " file://inittab.patch"
 
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

How to Patch the FSBL in a PetaLinux Project

Note: This method can't be used for v2016.4 PetaLinux Projects. PetaLinux tools use externalsrc methodology to fetch the source code from XSDK. Yocto does not allow patching in this externalsrc mechanism. Hence this method can't be used in Yocto.

1. Create a fsbl and files directory in meta-user layer as

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$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsbl/files

2. Copy patch files to <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsbl/files as

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$ cp 0001-FSBL.patch <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsbl/files

Note that patches should be generated based on the embeddedsw GIT repo which contains FSBL as the patches require the path into the repo to apply correctly.

3. Create a fsbl_%.bbappend file and add below content

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$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsbl/fsbl_%.bbappend

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# Patch for FSBL
# Note: do_configure_prepend task section is required only for 2017.1 release
# Refer https://github.com/Xilinx/meta-xilinx-tools/blob/rel-v2017.2/classes/xsctbase.bbclass#L29-L35
 
do_configure_prepend() {
    if [ -d "${S}/patches" ]; then
       rm -rf ${S}/patches
    fi
 
    if [ -d "${S}/.pc" ]; then
       rm -rf ${S}/.pc
    fi
}
 
SRC_URI_append = " \
        file://0001-FSBL.patch \
        "
 
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
 
#Add debug for FSBL(optional)
XSCTH_BUILD_DEBUG = "1"
 
#Enable appropriate FSBL debug or compiler flags
YAML_COMPILER_FLAGS_append = " -DXPS_BOARD_ZCU102"
 
# Note: This is not required if you are using Yocto
# CAUTION!: EXTERNALXSCTSRC and EXTERNALXSCTSRC_BUILD is required only for 2018.2 and below petalinux releases
EXTERNALXSCTSRC = ""
EXTERNALXSCTSRC_BUILD = ""

4. Remove the <plnx-proj-root>/components/plnx_workspace and clean your project workspace before rebuilding FSBL components

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$ petalinux-build -x mrproper

#Note: In v2018.1 PetaLinux release onwards "petalinux-build -x mrproper" command will remove <plnx-proj-root>/components/plnx_workspace directory
$ rm -rf <plnx-proj-root>/components/plnx_workspace

5. Rebuilding FSBL components

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$ petalinux-build -c bootloader

How to Patch the PMU Firmware in a PetaLinux Project

Note: This method can't be used for v2016.4 PetaLinux Projects. PetaLinux tools use externalsrc methodology to fetch the source code from XSDK. Yocto does not allow patching in this externalsrc mechanism. Hence this method can't be used in Yocto.

1. Create a pmu/pmu-firmware and files directory in meta-user layer as

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$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu/files

#For v2018.1 release onwards
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu-firmware/files

2. Copy patch files to <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu/files as

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$ cp 0001-PMUFW.patch <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu/files

#For v2018.1 release onwards
$ cp 0001-PMUFW.patch <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu-firmware/files

3. Create a pmu-firmware_%.bbappend file and add below content

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$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu/pmu-firmware_%.bbappend

#For v2018.1 or later PetaLinux releases only
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu-firmware/pmu-firmware_%.bbappend

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# Patch for PMUFW
# Note: do_configure_prepend task section is required only for 2017.1 release
# Refer https://github.com/Xilinx/meta-xilinx-tools/blob/rel-v2017.2/classes/xsctbase.bbclass#L29-L35
 
do_configure_prepend() {
    if [ -d "${S}/patches" ]; then
       rm -rf ${S}/patches
    fi
 
    if [ -d "${S}/.pc" ]; then
       rm -rf ${S}/.pc
    fi
}
 
SRC_URI_append = " \
        file://0001-PMUFW.patch \
        "
 
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"

# Enable appropriate PMUFW debug or compiler flags
YAML_COMPILER_FLAGS_append = " -DENABLE_EM"
 
# Note: This is not required if you are using Yocto
# CAUTION!: EXTERNALXSCTSRC and EXTERNALXSCTSRC_BUILD is required only for 2018.2 and below petalinux releases
EXTERNALXSCTSRC = ""
EXTERNALXSCTSRC_BUILD = ""

4. Remove the <plnx-proj-root>/components/plnx_workspace and clean your project workspace before rebuilding PMUFW components

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$ petalinux-build -x mrproper

#Note: In v2018.1 or later PetaLinux release "petalinux-build -x mrproper" command will remove <plnx-proj-root>/components/plnx_workspace directory
$ rm -rf <plnx-proj-root>/components/plnx_workspace

5. Rebuilding PMUFW components

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$ petalinux-build -c pmufw

...

Create a fsbl_%.bbappend file and add below content

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$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsbl/fsbl_%.bbappend

To enable debugs in FSBL:

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#Add debug for FSBL
XSCTH_BUILD_DEBUG = "1"

To add compiler flags in FSBL:

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#Add compiler flags for FSBL
YAML_COMPILER_FLAGS_append = " -DFSBL_PROT_BYPASS"

To add BSP flags(secure mode) in FSBL:

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#Add BSP flags for FSBL
YAML_BSP_CONFIG += "secure_mode"
YAML_BSP_CONFIG[secure_mode] = "set,true"

Create a pmu-firmware_%.bbappend file and add below content

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$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu/pmu-firmware_%.bbappend

#For v2018.1 or later PetaLinux releases only
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu-firmware/pmu-firmware_%.bbappend

To enable debugs in PMUFW refer this https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18841724/PMU+Firmware page for DEBUG flags list

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#Add debug for PMUFW
XSCTH_BUILD_DEBUG = "1"

To add compiler flags in PMUFW, see PMU FW Build Flags:

Info
Note that the method of loading the PMUFW can prevent early prints (during code initialization) from being output. See PMU Firmware > Using FSBL to load PMUFW for additional details.

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#Add compiler flags for PMUFW
YAML_COMPILER_FLAGS_append = " -DDEBUG_MODE -DXPFW_DEBUG_DETAILED"

To add BSP flags(secure mode) in PMUFW:

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#Add BSP flags for PMUFW
YAML_BSP_CONFIG += "secure_mode"
YAML_BSP_CONFIG[secure_mode] = "set,true"

To add BSP flags(debug mode) in PMUFW: For example if you want to enable https://github.com/Xilinx/embeddedsw/blob/release-2018.3/lib/sw_apps/zynqmp_pmufw/misc/xfpga_config.h#L34 debug is Xil BSP libraries

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#Add BSP flags for PMUFW
YAML_BSP_CONFIG += "debug_mode"
YAML_BSP_CONFIG[debug_mode] = "set,true"

...

Versions Compared

Old Version 26

New Version 27

Key

Table of Contents

Documentation

Working with a User Space Yocto Layer

Installing the meta-example layer on your host

About the meta-example layer

Configuring the layer path in the PetaLinux build system

Building the meta-layer example package based on a local source archive

Including the meta-layer example build output in the Linux root file system

Running the meta-layer example under QEMU

Patching the Linux Kernel of a PetaLinux Project

How to Modify inittab or getty in a PetaLinux Project

How to Patch the FSBL in a PetaLinux Project

How to Patch the PMU Firmware in a PetaLinux Project

Page Comparison

Versions Compared

Old Version 26

New Version 27

Key

Table of Contents

Documentation

Working with a User Space Yocto Layer

Installing the meta-example layer on your host

About the meta-example layer

Configuring the layer path in the PetaLinux build system

Building the meta-layer example package based on a local source archive

Including the meta-layer example build output in the Linux root file system

Running the meta-layer example under QEMU

Patching the Linux Kernel of a PetaLinux Project

How to Modify inittab or getty in a PetaLinux Project

How to Patch the FSBL in a PetaLinux Project

How to Patch the PMU Firmware in a PetaLinux Project