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

Table of Contents

Table of Contents
excludeTable of Contents

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 \

add the layer path in below config option.

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cd <plnx-proj-root>
petalinux-config --> Yocto Settings --> User Layers --> (/absolute_path_to_meta_layer/meta-example) user \layer   "

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_
0 
													--> ()    user layer 1


Move to your Yocto 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 <BUILD_DIR>/conf/local.conf file for YOCTO project <plnx-proj-root>/meta-user/conf/petalinuxbsp.conf file for PetaLinux project 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

## From 2021.1 onwards
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-bsp/embeddedsw/ 
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
## From 2021.1 onwards 
$ cp 0001-FSBL.patch <plnx-proj-root>/project-spec/meta-user/recipes-bsp/embeddedsw/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
## From 2021.1 onwards
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/embeddedsw/fsbl-firmware_%.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


Configuring the FSBL and PMUFW Debugs in a PetaLinux Project


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
# From 2021.1 onwards
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/embeddedsw/fsbl-firmware_%.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"


By pass PMUFW debug logs on different UART console:
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YAML_SERIAL_CONSOLE_STDIN_forcevariable = "psu_uart_1"
YAML_SERIAL_CONSOLE_STDOUT_forcevariable = "psu_uart_1"
Remove the <plnx-proj-root>/components/plnx_workspace and clean you project workspace before rebuilding FSBL or 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
$ petalinux-build

How to Update psu_init Files in PetaLinux Project

Info

Note: PSU_INIT files are generated based on HDF or XSA parsing, Hence these files can't be patched on top of embedded_sw repo using Yocto SRC_URI variable. Alternatively we can update these files by editing <plnx-proj-root>/project-spec/hw-description/psu_init.c and copy to FSBL build workspace during do_compile_prepend bitbake task.


1. Modify <plnx-proj-root>/project-spec/hw-description/psu_init.c file as per your requirement 

2. Create a FSBL bbappend file under <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsblembeddedsw/fsbl-firmware_%.bbappend and bbappend and add below content to update psu_init.c changes to FSBL

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# For 2018.2 and below versions
do_compile_prepend(){
   install -m 0644 ${TOPDIR}/../project-spec/hw-description/psu_init.c ${TOPDIR}/../components/plnx_workspace/fsbl/fsbl_hwproj/psu_init.c
}

# For 2018.3 and later versions we removed FSBL and PMUFW external workspace from <plnx-proj-root>/components/plnx_workspace directory
# to align Yocto patching mechanism. Hence we are copying the files to build workspace(${B})
# https://github.com/Xilinx/meta-xilinx-tools/blob/rel-v2018.3/classes/xsctbase.bbclass#L14
do_compile_prepend(){
   install -m 0644 ${TOPDIR}/../project-spec/hw-description/psu_init.c ${B}/fsbl/psu_init.c
}

How to Add Pre-built Libraries in PetaLinux or Yocto

Recipes

Projects


1. Create a new recipe or in existing recipe in meta-user layer as shown Create an application/recipe and copy prebuilt library and header files with the following commands. Assuming prebuilt library name is libcpsample.so.1.0.1.    

In PetaLinux Flow:

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$ mkdir -p petalinux-create -t apps --template install --name libcpsample --enable
$ cp libcpsample.so.1.0.1 <plnx-proj-root>/project-spec/meta-user/recipes-apps/libcpsample/files
2. Copy pre-built libraries files and header file required for libraries to <plnx-proj-

$ cp cpsample.h <plnx-proj-root>/project-spec/meta-user/recipes-apps/libcpsample/files
as
(or) You can use the below single command to achieve the above functionality.
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$ cp  petalinux-create -t apps --template install --name libcpsample --enable --srcuri "<path-to-dir>/libcpsample.so.1.0.1 <plnx<path-projto-root>/project-spec/meta-userdir>/cpsample.h>"

In Yocto Flow:

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$ mkdir -p <layer-path>/recipes-apps/libcpsample/files
$ cp cpsample.h <plnx-proj-root>/project-spec/meta-usertouch <layer-path>/recipes-apps/libcpsample/libcpsample.bb
$ cp libcpsample.so.1.0.1 <layer-path>/recipes-apps/libcpsample/files
$ cp cpsample.h <layer-path>/recipes-apps/libcpsample/files


32. Add the below content to recipe(bb) file
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#
# This file is the libcpsample recipe.
#
 
SUMMARY = "Sample pre-built library copy to rootfs"
SECTION = "libs"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
 
SRC_URI = " \
    file://libcpsample.so.1.0.1 \
    file://cpsample.h \
"
 
S = "${WORKDIR}"
 
# Add dependency libraireslibraries if any
# for example DEPENDS = "libpcap"
 
# If you need to create a symbolic link using the pre-built libraries you should use oe_soinstall.
# This copies libraries to "{TARGET_ROOTFS}/usr/lib" directory and create a symlink as
# lrwxrwxrwx libcpsample.so.1.0 -> libcpsample.so.1.0.1
# -rwxr-xr-x libcpsample.so.1.0.1
 
do_install() {
    install -d ${D}${libdir}
    oe_soinstall ${S}/libcpsample.so.1.0.1 ${D}${libdir}
    install -d -m 0655 ${D}${includedir}/CPSAMPLE
    install -m 0644 ${S}/*.h ${D}${includedir}/CPSAMPLE/
}
 
# Inhibit warnings about files being stripped
INSANE_SKIP_${PN} = "ldflags"
INSANE_SKIP_${PN} = "already-stripped"
 
# If you don't have .h file to copy to /usr/include add something like below
# FILES_${PN} = "${libdir}/*.so.*"
 
FILES_${PN} = "${libdir}/*.so.* ${includedir}/*"
FILES_${PN}-dev = "${libdir}/*.so"
4. Build the pre-built library recipe
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$ petalinux-build -c libcpsamplerootfs


Creating Libraries in a PetaLinux Project


1. Create a library using petalinux PetaLinux tools
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$ petlainux-create -t apps --template c --name libsample --enable
2. Modify the libsample.bb recipe file <plnx-proj-root>/project-spec/meta-user/recipes-apps/libsample/libsample.bb as
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#
# This file is the libsample recipe.
#
 
SUMMARY = "Simple libsample application"
SECTION = "libs"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
 
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
 
SRC_URI = " \
          file://sample.c \
          file://sample.h \
          file://Makefile \
         "
 
S = "${WORKDIR}"
 
PACKAGE_ARCH = "${MACHINE_ARCH}"
PROVIDES = "sample"
TARGET_CC_ARCH += "${LDFLAGS}"
 
do_install() {
    install -d ${D}${libdir}
    install -d ${D}${includedir}
    oe_libinstall -so libsample ${D}${libdir}
    # This is optional and depends if you have any headers to copied along with libraries
    # This example includes sample.h to to copied to <TARGET_ROOTFS>/usr/lib/SAMPLE/sample.h
    install -d -m 0655 ${D}${includedir}/SAMPLE
    install -m 0644 ${S}/*.h ${D}${includedir}/SAMPLE/
}
 
FILES_${PN} = "${libdir}/*.so.* ${includedir}/*"
FILES_${PN}-dev = "${libdir}/*.so"
3. Modify the <plnx-proj-root>/project-spec/meta-user/recipes-apps/libsample/files/Makefile generated from petalinux PetaLinux tools as
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APP = sample
 
LIBSOURCES=*.c
OUTS = *.o
NAME := sample
MAJOR = 1.0
MINOR = 1
VERSION = $(MAJOR).$(MINOR)
 
all: lib$(NAME).so
lib$(NAME).so.$(VERSION): $(OUTS)
    $(CC) $(LDFLAGS) $(OUTS) -shared -Wl,-soname,lib$(NAME).so.$(MAJOR) -o lib$(NAME).so.$(VERSION)
 
lib$(NAME).so: lib$(NAME).so.$(VERSION)
    rm -f lib$(NAME).so.$(MAJOR) lib$(NAME).so
    ln -s lib$(NAME).so.$(VERSION) lib$(NAME).so.$(MAJOR)
    ln -s lib$(NAME).so.$(MAJOR) lib$(NAME).so
 
%.o: %.c
    $(CC) $(CFLAGS) -c -fPIC $(LIBSOURCES)
 
clean:
    rm -rf *.o *.so *.so.*
4. Build the library recipe
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$ petalinux-build -c libsample

Creating Apps(which uses libraries) in PetaLinux Project

...


1. Create a library using petalinux PetaLinux tools
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$ petlainux-create -t apps --template c --name sampleapp --enable
2. Modify the sampleapp.bb recipe file <plnx-proj-root>/project-spec/meta-user/recipes-apps/sampleapp/sampleapp.bb as
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#
# This file is the sampleapp recipe.
#
 
SUMMARY = "Simple sampleapp application"
SECTION = "PETALINUX/apps"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
 
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
 
SRC_URI = " \
          file://sampleapp.c \
         "
 
S = "${WORKDIR}"
 
DEPENDS += " libsample"
 
#This uses libsample.so.1.0.1 (-lsample)
do_compile() {
    ${CC} ${CFLAGS} ${LDFLAGS} -o sampleapp sampleapp.c -lsample
}
 
do_install() {
    install -d ${D}${bindir}
    install -d -m 0755 sampleapp ${D}${bindir}
}
 
FILES_${PN} += "sampleapp"
3. Modify the <plnx-proj-root>/project-spec/meta-user/recipes-apps/libsample/files/sampleapp.c generated from petalinux PetaLinux tools as
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#include <stdio.h>
#include <SAMPLE/sample.h>  // From above libs <TARGET_ROOTFS>/usr/lib/SAMPLE/sample.h
 
int main(int argc, char **argv)
{
    printf("Hello World!\n");
    sample_hello();
    return 0;
}
4. Build the apps recipe
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$ petalinux-build -c sampleapp

How to

Auto Mount SD card in Yocto Recipes

Auto Run Application at Startup

1. Create a

base-files directory in meta-user layer as

library using PetaLinux tools

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$ mkdirpetalinux-create -pt apps <plnx-proj-root>/project-spec/meta-user/recipes-core/base-files
2. Create a base-files_%.bbappend file and add below content
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$ vim -template install -n myapp-init --enable

2. Edit the file <plnx-proj-root>/project-spec/meta-user/recipes-

core

apps/

base

myapp-

files/base-files_%.bbappend #base-files_%.bbappend content dirs755 += "/media/card" do_install_append() { sed -i '/mmcblk0p1/s/^#//g' ${D}${sysconfdir}/fstab }3. Rebuild rootfs
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$ petalinux-build

How to Configure a Second Ethernet Interface(eth1) to Get the IP Address from DHCP in Yocto Recipes

Method 1: Append auto eth1 to existing interfaces file

1. Create a init-ifupdown directory in meta-user layer as
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$ mkdir -p

init/myappinit.bb. The file should look like the following:

Code Block
themeMidnight
#this file is the myapp-init recipe.
#

SUMMARY = "Simple myapp-init application"
SECTION = "PETALINUX/apps"
LICENSE = "MIT"

LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"

SRC_URI = "file://myapp-init \
"

S = "${WORKDIR}"
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"

inherit update-rc.d
INITSCRIPT_NAME = "myapp-init"
INITSCRIPT_PARAMS = "start 99 S ."

do_install() {
	install -d ${D}${sysconfdir}/init.d
	install -m 0755 ${S}/myapp-init ${D}${sysconfdir}/init.d/myapp-init
}
FILES_${PN} += "${sysconfdir}/*"

3. To run myapp as daemon, edit the file <plnx-proj-root>/project-spec/meta-user/recipes-

core

apps/myapp-init

-ifupdown/2. Create a init_ifupdown_%.bbappend file and add below content
Code Blocklanguagebash

/files/myapp-init.

Code Block
themeMidnight
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/init-ifupdown_%.bbappend
 
# init-ifupdown_%.bbappend content
 
do_install_append() {
    sed -i '/iface eth0 inet dhcp/ a auto eth1' ${D}${sysconfdir}/network/interfaces
}
3. Rebuild rootfs
Code Block
languagebash
themeMidnight
$ petalinux-build

Method 2: Use your own interfaces file

1. Create a init-ifupdown directory in meta-user layer as
Code Block
languagebash
themeMidnight
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/files
2. Create your own network interface file as show below
Code Block
languagebash
themeMidnight
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/files/myinterfaces
 
# myinterfaces content
 
# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)
 
# The loopback interface
auto lo
iface lo inet loopback
 
# Wireless interfaces
iface wlan0 inet dhcp
    wireless_mode managed
    wireless_essid any
    wpa-driver wext
    wpa-conf /etc/wpa_supplicant.conf
 
iface atml0 inet dhcp
 
# Wired or wireless interfaces
auto eth0
iface eth0 inet dhcp
 
# Add auto config for eth1
auto eth1
iface eth1 inet dhcp
 
# Ethernet/RNDIS gadget (g_ether)
# ... or on host side, usbnet and random hwaddr
iface usb0 inet static
    address 192.168.7.2
    netmask 255.255.255.0
    network 192.168.7.0
    gateway 192.168.7.1
 
# Bluetooth networking
iface bnep0 inet dhcp
3. Create a init_ifupdown_%.bbappend file and add below content
Code Block
languagebash
themeMidnight
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/init-ifupdown_%.bbappend
 
# init-ifupdown_%.bbappend content
 
SRC_URI += " \#!/bin/sh
DAEMON=/usr/bin/myapp-init
start ()
{
        echo " Starting myapp-init"
        start-stop-daemon -S -o --background -x $DAEMON
}
stop ()
{
        echo " Stoping myapp-init"
        start-stop-daemon -K -x $DAEMON
}
restart()
{
        stop
        start
}

[ -e $DAEMON ] || exit 1

        case "$1" in
                start)
                        start; ;;
                stop)
                        stop; ;;
                restart)
                        restart; ;;
                *)
           file://myinterfaces \         "   FILESEXTRAPATHS_prependecho "Usage:= $0 "${THISDIR}/files:"{start|stop|restart}"
   #  Overwrite interface file with myinterface file in rootfs do_install_append() {      install -m 0644 ${WORKDIR}/myinterfaces ${D}${sysconfdir}/network/interfaces
}
4. Rebuild rootfs
bash
Code Block
language
  exit 1
        esac
exit $?

4. Build the project

Code Block
themeMidnight
$ petalinux-build

How to

Run RootFS Post Process Command in PetaLinuxBelow is one of the example and you can add rootfs post process command in 

Auto Mount SD card in Yocto Recipes


1. Create a base-files directory in meta-user layer as
Code Block
themeMidnight
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/
images/petalinuxbsp-user-image.bbappend file. You add a function which can perform modifying file, deleting and adding file and directories.

Create a petalinux-user-image.bbappend file in meta-user layer as show below if doesn't exists(Note: Don't use project-spec/meta-user/recipes-core/images/petalinux-image-full.bbappend(2018.3 or later) or petalinux-image.bbappend(2018.2 or below))

base-files
2. Create a base-files_%.bbappend file and add below content
Code Block
themeMidnight
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/

...

base-files/

...

Create a post process function as shown below in petalinux-user-image.bbappend 

...

languagebash
themeMidnight
titlepetalinux-user-image.bbappend

...

base-files_%.bbappend
 
#base-files_%.bbappend content
 

...


...

dirs755 

...

+= "/media/card"
 
do_install_append() {

...

 

...

 

...

 

...

 

...

sed -i '/

...

mmcblk0p1/s/^#//g' ${

...

D}${sysconfdir}/

...

Clean petalinux-user-image sstate and rebuild petalinux-user-image recipe.

...

languagebash
themeMidnight

...

fstab
}
3. Rebuild rootfs
Code Block
themeMidnight
$ petalinux-build

How to

Add Users and Set Passwords for Users in PetaLinuxCreate a petalinux-user-image.bbappend file

Configure a Second Ethernet Interface(eth1) to Get the IP Address from DHCP in Yocto Recipes

Method 1: Append auto eth1 to existing interfaces file


1. Create a init-ifupdown directory in meta-user layer as show below (Note: Don't use project-spec/meta-user/recipes-core/images/petalinux-image-full.bbappend(2018.3 or later) or petalinux-image.bbappend(2018.2 or below))
Code Block
languagebash
themeMidnight
$ mkdir 
vim
-p <plnx-proj-root>/project-spec/meta-user/recipes-core/
images/petalinux-user-image.bbappendInherit extrausers.bbclass from openembedded-core and add users in petalinux-user-image.bbappend 
init-ifupdown/
2. Create a init_ifupdown_%.bbappend file and add below content
Code Block
languagebash
themeMidnight
titlepetalinux-user-image.bbappend# petalinux-user-image
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/init-ifupdown_%.bbappend
 
# init-ifupdown_%.bbappend content
inherit
 
extrausers

EXTRA
do_
USERS
install_
PARAMS
append() 
=
{
"\
    
usermod
sed -
P
i 
root root; \ useradd -P test@123 test1; \ useradd -P test@987 test2; \ "
'/iface eth0 inet dhcp/ a auto eth1' ${D}${sysconfdir}/network/interfaces
}
3. Rebuild rootfs
Code Block
languagebash
themeMidnight
$ petalinux-build
-x cleanall $ petalinux-build

How to Override a Recipe Variable in PetaLinux

...

Create a directory recipes-devtools/protobuf directory in <plnx-porj-root>/project-spec/meta-user

Code Block
languagebash
themeMidnight
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-devtools/protobuf

...

Method 2: Use your own interfaces file


1. Create a init-ifupdown directory in meta-user layer as
Code Block
languagebash
themeMidnight
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/files
2. Create your own network interface file as show below
Code Block
languagebash
themeMidnight
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/files/myinterfaces
 
# myinterfaces content
 
# /etc/network/interfaces -- configuration file for ifup(8), ifdown(8)
 
# The loopback interface
auto lo
iface lo inet loopback
 
# Wireless interfaces
iface wlan0 inet dhcp
    wireless_mode managed
    wireless_essid any
    wpa-driver wext
    wpa-conf /etc/wpa_supplicant.conf
 
iface atml0 inet dhcp
 
# Wired or wireless interfaces
auto eth0
iface eth0 inet dhcp
 
# Add auto config for eth1
auto eth1
iface eth1 inet dhcp
 
# Ethernet/RNDIS gadget (g_ether)
# ... or on host side, usbnet and random hwaddr
iface usb0 inet static
    address 192.168.7.2
    netmask 255.255.255.0
    network 192.168.7.0
    gateway 192.168.7.1
 
# Bluetooth networking
iface bnep0 inet dhcp
3. Create a init_ifupdown_%.bbappend file and add below content
Code Block
languagebash
themeMidnight
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/init-ifupdown_%.bbappend
 
# init-ifupdown_%.bbappend content
 
SRC_URI += " \
        file://myinterfaces \
        "
 
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
 
# Overwrite interface file with myinterface file in rootfs
do_install_append() {
     install -m 0644 ${WORKDIR}/myinterfaces ${D}${sysconfdir}/network/interfaces
}
4. Rebuild rootfs
Code Block
languagebash
themeMidnight
$ petalinux-build


How to Run RootFS Post Process Command in PetaLinux


Below is one of the example and you can add rootfs post process command in <plnx-proj-root>/project-spec/meta-user/recipes-core/images/petalinuxbsp-user-image.bbappend file. You add a function which can perform modifying file, deleting and adding file and directories.
  1. Create a petalinux-user-image.bbappend file in meta-user layer as show below if doesn't exists(Note: Don't use project-spec/meta-user/recipes-core/images/petalinux-image-full.bbappend(2018.3 or later) or petalinux-image.bbappend(2018.2 or below))

    Code Block
    languagebash
    themeMidnight
    $ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/images/petalinux-user-image.bbappend


  2. Create a post process function as shown below in petalinux-user-image.bbappend 

    Code Block
    languagebash
    themeMidnight
    titlepetalinux-user-image.bbappend
    # petalinux-user-image.bbappend content
    
    # Auto DHCP for second network interface
    rootfs_postprocess_function() {
    	if [ -e ${IMAGE_ROOTFS}/etc/network/interfaces ]; then
    		sed -i '/iface eth0 inet dhcp/ a auto eth1' ${IMAGE_ROOTFS}/etc/network/interfaces
    	fi
    }
    
    ROOTFS_POSTPROCESS_COMMAND_append = " \
      rootfs_postprocess_function; \
    "


  3. Clean petalinux-user-image sstate and rebuild petalinux-user-image recipe.

    Code Block
    languagebash
    themeMidnight
    $ petalinux-build -x cleansstate
    $ petalinux-build


How to Add Users and Set Passwords for Users in PetaLinux

  1. Create a petalinux-user-image.bbappend file in meta-user layer as show below (Note: Don't use project-spec/meta-user/recipes-core/images/petalinux-image-full.bbappend(2018.3 or later) or petalinux-image.bbappend(2018.2 or below))

    Code Block
    languagebash
    themeMidnight
    $ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/images/petalinux-user-image.bbappend


  2. Inherit extrausers.bbclass from openembedded-core and add users in petalinux-user-image.bbappend 

    Code Block
    languagebash
    themeMidnight
    titlepetalinux-user-image.bbappend
    # petalinux-user-image.bbappend content
    inherit extrausers
    
    EXTRA_USERS_PARAMS = "\
        usermod -P root root; \
        useradd -P test@123 test1; \
        useradd -P test@987 test2; \
        "


  3. Rebuild rootfs

    Code Block
    languagebash
    themeMidnight
    $ petalinux-build -x cleanall
    $ petalinux-build


How to Override a Recipe Variable in PetaLinux

  1. First step is to find the recipe directory hierarchy, search the recipe in https://layers.openembedded.org/layerindex/branch/rocko/recipes/
  2. Here we are taking Protobuf package as example as SRC_URI like is broken in Yocto 2.4 release. Same concept applies to all the recipes. Protobuf is categorized in meta-openembedded/meta-oe/recipes-devtools/protobuf
  3. Create a directory recipes-devtools/protobuf directory in <plnx-porj-root>/project-spec/meta-user

    Code Block
    languagebash
    themeMidnight
    $ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-devtools/protobuf


  4. Create a protobuf_%.bbappend file. Note: The % wildcard is actually allow matching of the name and version up to the point of encountering the %. This approach will allow for matching of the major or major.minor. version of recipes.

    Code Block
    languagebash
    themeMidnight
    $ vim <plnx-proj-root>/project-spec/meta-user/recipes-devtools/protobuf/protobuf_%.bbappend


  5. Now override a recipe variable for protobuf recipe.

    Code Block
    languagebash
    themeMidnight
    titleprotobuf_%.bbappend
    # protobuf_%.bbappend content
    SRC_URI = "git://github.com/google/protobuf.git"


  6. Build protobuf

    Code Block
    languagebash
    themeMidnight
    $ petalinux-build -c protobuf -x cleanall
    $ petalinux-build -c protobuf


...

In order to utilize the sstate cache feature in PetaLinux projects follow these steps.

...

these steps.

  1. Download and untar the PetaLinux release sstate-cache files from https://www.xilinx.com/support/download/index.html/content/xilinx/en/downloadNav/embedded-design-tools.html. Here we are taking 2019.2 as an example.
  2. Go to your 2019.2 PetaLinux project and set the following options using petalinux-config

    Code Block
    languagebash
    themeMidnight
    titleSSTATE Template
    $ petalinux-config ---> Yocto Settings ---> Add pre-mirror url ---> file://<path_to_downloads>
    $ petalinux-config ---> Yocto Settings ---> Local sstate feeds settings ---> local sstate feeds url ---> <path_to_sstate_aarch64_2019.2/aarch64>


    Code Block
    languagebash
    themeMidnight
    titleSSTATE TemplateSSTATE Example Usage
    $ petalinux-config ---> Yocto Settings ---> Add pre-mirror url ---> file:///opt/xilinx/petalinux/2019.2/downloads
    $ petalinux-config ---> Yocto Settings ---> Add pre-mirror url ---> file://<path_to_downloads>
    $ petalinux-config ---> Yocto Settings ---> Local sstate feeds settings ---> local sstate feeds url ---> <path_to_sstate_aarch64_2019.2/aarch64> Local sstate feeds settings ---> local sstate feeds url ---> /opt/xilinx/petalinux/2019.2/sstate_aarch64_2019.2/aarch64


    Info

    Note: For PREMIRRORS usage you need to add the file, git, http or https protocol followed by the path, but this is not true for SSTATE feeds.


  3. For setting up the download and shared state directories add the following variables in the <plnx-proj-root>/project-spec/meta-user/conf/petalinuxbsp.conf file.

    Code Block
    languagebash
    themeMidnight
    titleDL_DIR and SSTATE_DIR Template
    DL_DIR = "<PATH-TO-DOWNLOADS-DIRECTORY>/<PetaLinux-Version>/downloads"
    SSTATE_DIR = "<PATH-TO-SSTATE-DIRECTORY>/<PetaLinux-Version>/sstate-cache/<ARCH>"


    $ petalinux-config ---> Yocto Settings ---> Add pre-mirror url ---> file:///opt/xilinx/petalinux/2019.2/downloads $ petalinux-config ---> Yocto Settings ---> Local sstate feeds settings ---> local sstate feeds url ---> /opt/xilinx/petalinux
    Code Block
    languagebash
    themeMidnight
    titleSSTATE Example Usage
    DL_DIR and SSTATE_DIR example usage
    DL_DIR = "/home/$USER/plnx-workspace/2019.2/downloads"
    SSTATE_DIR = "/home/$USER/plnx-workspace/2019.2/sstate_aarch64_2019.2-cache/aarch64"


    Info

    Note: For PREMIRRORS usage DL_DIR and SSTATE_DIR directories should have read and write permission.


  4. Now you need to

    add the file, git, http or https protocol followed by the path, but this is not true for SSTATE feeds.

    For setting up the download and shared state directories add the following variables in the <plnx-proj-root>/project-spec/meta-user/conf/petalinuxbsp.conf file.start the build and if you are building the SDK (petalinux --sdk) then enabling the network is mandatory for a fresh build.

    DL_DIR = "<PATH-TO-DOWNLOADS-DIRECTORY>/<PetaLinux-Version>/downloads" SSTATE_DIR = "<PATH-TO-SSTATE-DIRECTORY>/<PetaLinux-Version>/sstate-cache/<ARCH>"
    Code Block
    languagebash
    themeMidnight
    titleDL_DIR and SSTATE_DIR Template
    Build Commands
    $ petalinux-build
    $ petalinux-build --sdk


  5. If you are building without network access then set the BB_NO_NETWORK variable.

    Now you need to start the build and if you are building the SDK (petalinux --sdk) then enabling the network is mandatory for a fresh build.

    Code Block
    languagebash
    themeMidnight
    titleBuild Commands
    $ petalinux-build
    $ petalinux-build --sdk
    If you are building without network access then set the BB_NO_NETWORK variable
    Code Block
    languagebash
    themeMidnight
    titleDL_DIR and SSTATE_DIR example usage
    DL_DIR = "/home/$USER/plnx-workspace/2019.2/downloads"
    SSTATE_DIR = "/home/$USER/plnx-workspace/2019.2/sstate-cache/aarch64"
    Info

    Note: DL_DIR and SSTATE_DIR directories should have read and write permission.

    Set BB_NO_NETWORK
    $ petalinux-config ---> Yocto Settings ---> [*] Enable BB NO NETWORK


    Info

    Note: In case the project was built previously, run petalinux-build -x mrproper with above variables to reduce build time especially when using petalinux-build --sdk.


How to disable hwcodecs(Xilinx vcu firmware) in PetaLinux for ZynqMP EV devices

  1. By default hwcodecs are enabled in petalinux project when zynqmp ev device xsa is parsed while creating the project. To disable hwcodecs add below variable in <plnx-proj-root>/project-spec/meta-user/conf/petaliuxbsp.conf

    Code Block
    languagebash
    themeMidnight
    IMAGE_FEATURES_remove = "hwcodecs"


  2. Clean and rebuild complete project.

    Code Block
    languagebash
    themeMidnighttitleSet BB_NO_NETWORK
    $ petalinux-configbuild --->x Yocto Settings ---> [*] Enable BB NO NETWORK
    Info
    Note: In case the project was built previously, run petalinux-build -x mrproper with above variables to reduce build time especially when using petalinux-build --sdk.
    mrproper
    $ petalinux-build


Yocto References 

...