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
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
$ 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
$ 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 directory, add the layer path in below config option.
cd <plnx-proj-root> petalinux-config --> Yocto Settings --> User Layers --> (/absolute_path_to_meta_layer/meta-example) user layer 0 --> () user layer 1
BBLAYERS := " \ ${SDKBASEMETAPATH}/layers/poky/meta \ ${SDKBASEMETAPATH}/layers/poky/meta-poky \ /absolute_path_to_meta_layer/meta-example \ "
Building the meta-layer example package based on a local source archive
The recipe we are going to build is https://github.com/DynamicDevices/meta-example/blob/master/recipes-example/bbexample/bbexample-lt_1.0.bb
The recipe bbexample-lt is using some variables
1. SRC_URI Space-delimited list of URIs to download source code, patches, and other files from git, local absolute path, https, ftp etc.
2. PN is the Package Name. The value of this variable is derived by BitBake from the base name of the recipe file.
3. PV is the Package Version. which is derived by BitBake from the base name of the recipe file
# Use local tarball SRC_URI = "file://bbexample-${PV}.tar.gz"
The recipe bbexample-lt can invoked using the following command
$ petalinux-build -c bbexample-lt
here is the command output
$ 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
IMAGE_INSTALL_append = " bbexample-lt"
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.
recipes-core/images/core-image-minimal.bbappend
IMAGE_INSTALL += " bbexample-lt"
Running the meta-layer example under QEMU
1. Rebuild your layer
$ petalinux-build -c bbexample_lt -x cleansstate
$ petalinux-build -c kernel
$ petalinux-boot --qemu --kernel
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
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
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/sysvinit/sysvinit-inittab
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/sysvinit/sysvinit-inittab_%.bbappend
SRC_URI_append = " file://inittab" FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
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
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-bsp/fsbl/files ## From 2021.1 onwards $ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-bsp/embeddedsw/
$ 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
3. Create a fsbl_%.bbappend file and add below content
$ 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
# 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 = ""
$ 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
$ 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
$ 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
$ 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
$ 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
# 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
$ 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 -c pmufw
Configuring the FSBL and PMUFW Debugs in a PetaLinux Project
Create a fsbl bbappend file and add below content
$ 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
#Add debug for FSBL XSCTH_BUILD_DEBUG = "1"
#Add compiler flags for FSBL YAML_COMPILER_FLAGS_append = " -DFSBL_PROT_BYPASS"
#Add BSP flags for FSBL YAML_BSP_CONFIG += "secure_mode" YAML_BSP_CONFIG[secure_mode] = "set,true"
$ 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
#Add debug for PMUFW XSCTH_BUILD_DEBUG = "1"
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.
#Add compiler flags for PMUFW YAML_COMPILER_FLAGS_append = " -DDEBUG_MODE -DXPFW_DEBUG_DETAILED"
#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
#Add BSP flags for PMUFW YAML_BSP_CONFIG += "debug_mode" YAML_BSP_CONFIG[debug_mode] = "set,true"
YAML_SERIAL_CONSOLE_STDIN_forcevariable = "psu_uart_1" YAML_SERIAL_CONSOLE_STDOUT_forcevariable = "psu_uart_1"
$ 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
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/embeddedsw/fsbl-firmware_%.bbappend and add below content to update psu_init.c changes to FSBL
# 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 Projects
1. 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:
$ 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 $ cp cpsample.h <plnx-proj-root>/project-spec/meta-user/recipes-apps/libcpsample/files
$ petalinux-create -t apps --template install --name libcpsample --enable --srcuri "<path-to-dir>/libcpsample.so.1.0.1 <path-to-dir>/cpsample.h>"
In Yocto Flow:
$ mkdir -p <layer-path>/recipes-apps/libcpsample/files $ touch <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
# # 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 libraries 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"
$ petalinux-build -c rootfs
Creating Libraries in a PetaLinux Project
1. Create a library using petalinux tools
$ petlainux-create -t apps --template c --name libsample --enable
# # 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"
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.*
$ petalinux-build -c libsample
Creating Apps(which uses libraries) in PetaLinux Project
1. Create a library using petalinux tools
$ petlainux-create -t apps --template c --name sampleapp --enable
# # 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"
#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; }
$ petalinux-build -c sampleapp
How to Auto Run Application at Startup
1. Create a library using petalinux tools
$ petalinux-create -t apps --template install -n myapp-init --enable
2. Edit the file <plnx-proj-root>/project-spec/meta-user/recipes-apps/myapp-init/myappinit.bb. The file should look like the following:
#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-init1 ${D}${sysconfdir}/init.d/myapp-init1 } FILES_${PN} += "${sysconfdir}/*"
3. To run myapp as daemon, edit the file <plnx-proj-root>/project-spec/meta-user/recipes-apps/myapp-init/files/myapp-init.
#!/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; ;; *) echo "Usage: $0 {start|stop|restart}" exit 1 esac exit $?
4. Build the project
petalinux-build
How to Auto Mount SD card in Yocto Recipes
1. Create a base-files directory in meta-user layer as
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/base-files
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/base-files/base-files_%.bbappend #base-files_%.bbappend content dirs755 += "/media/card" do_install_append() { sed -i '/mmcblk0p1/s/^#//g' ${D}${sysconfdir}/fstab }
$ 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
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/
$ 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 }
$ petalinux-build
Method 2: Use your own interfaces file
1. Create a init-ifupdown directory in meta-user layer as
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/init-ifupdown/files
$ 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
$ 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 }
$ 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.
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))
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/images/petalinux-user-image.bbappend
Create a post process function as shown below in petalinux-user-image.bbappend
petalinux-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; \ "
Clean petalinux-user-image sstate and rebuild petalinux-user-image recipe.
$ petalinux-build -x cleansstate $ petalinux-build
How to Add Users and Set Passwords for Users in PetaLinux
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))
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/images/petalinux-user-image.bbappend
Inherit extrausers.bbclass from openembedded-core and add users in petalinux-user-image.bbappend
petalinux-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; \ "
Rebuild rootfs
$ petalinux-build -x cleanall $ petalinux-build
How to Override a Recipe Variable in PetaLinux
- First step is to find the recipe directory hierarchy, search the recipe in https://layers.openembedded.org/layerindex/branch/rocko/recipes/
- 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
Create a directory recipes-devtools/protobuf directory in <plnx-porj-root>/project-spec/meta-user
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-devtools/protobuf
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.
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-devtools/protobuf/protobuf_%.bbappend
Now override a recipe variable for protobuf recipe.
protobuf_%.bbappend# protobuf_%.bbappend content SRC_URI = "git://github.com/google/protobuf.git"
Build protobuf
$ petalinux-build -c protobuf -x cleanall $ petalinux-build -c protobuf
How to Enable Verbose in sysvinit
- First step is to find the recipe directory hierarchy, search the recipe in http://layers.openembedded.org/layerindex/branch/thud/recipes/
- sysvinit is categorized in meta/recipes-core/sysvinit
Create a directory recipes-core/sysvinit directory in <plnx-porj-root>/project-spec/meta-user
$ mkdir -p <plnx-proj-root>/project-spec/meta-user/recipes-core/sysvinit
Create a sysvinit_%.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.
$ vim <plnx-proj-root>/project-spec/meta-user/recipes-core/sysvinit/sysvinit_%.bbappend
Now enable verbose for sysvinit recipe (refer http://cgit.openembedded.org/openembedded-core/tree/meta/recipes-core/sysvinit/sysvinit/rcS-default?h=thud#n15)
sysvinit_%.bbappend# sysvinit_%.bbappend content do_install_prepend () { sed -i 's/VERBOSE=no/VERBOSE=yes/' ${WORKDIR}/rcS-default }
Clean and rebuild sysvinit
$ petalinux-build -c sysvinit -x cleanall $ petalinux-build -c sysvinit
How to reduce build time using SSTATE CACHE
The OpenEmbedded(OE) build system produces a lot of intermediate output when processing the many tasks entailed in building the packages comprising the Linux OS stack. SSTATE(Shared State) CACHE provides a cache mechanism which drastically reduces build time, especially when you create a new PetaLinux project and run "petalinux-build --sdk". The OE build system detects changes in the "inputs" to a given task by creating a checksum (or signature) of the task's inputs. If the checksum changes, the system assumes the inputs have changed and the task needs to be rerun. The intermediate output can be reused for future builds and shared between multiple build environments to speed up the build process.
Two key variables are used with the shared state cache feature. The SSTATE_DIR variable contains the path to the shared state cache. The variable DL_DIR tells BitBake where to place the source downloads. The default setting places the files in the directory downloads beneath the top directory(TOPDIR) of your build environment. The variable TOPDIR contains the full (absolute) path to the build environment. Source downloads can be shared among multiple build environments.
For best practice you need to set DL_DIR and SSTATE_DIR outside the petalinux project so that when you run "petalinux-build -s mrproper" which removes build(TOPDIR)directory forcefully, but retaining DL_DIR and SSTATE_DIR directories. These contents can be reused for incremental build or building another project. Note: You can use DL_DIR content for all the PetaLinux project irrespective of the architecture(AARCH64, ARM, MicroBlaze) but SSTATE_DIR can be used for only one architecture. For example, if you build a AARCH64 PetaLinux project the content of SSTATE_DIR can be reused for another AARCH64 project but not for ARM or MicroBlaze projects.
In order to utilize the sstate cache feature in PetaLinux projects follow these steps.
- 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.
Go to your 2019.2 PetaLinux project and set the following options using petalinux-config
SSTATE 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>
SSTATE Example Usage$ 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/2019.2/sstate_aarch64_2019.2/aarch64
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.
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.
DL_DIR and SSTATE_DIR TemplateDL_DIR = "<PATH-TO-DOWNLOADS-DIRECTORY>/<PetaLinux-Version>/downloads" SSTATE_DIR = "<PATH-TO-SSTATE-DIRECTORY>/<PetaLinux-Version>/sstate-cache/<ARCH>"
DL_DIR and SSTATE_DIR example usageDL_DIR = "/home/$USER/plnx-workspace/2019.2/downloads" SSTATE_DIR = "/home/$USER/plnx-workspace/2019.2/sstate-cache/aarch64"
Note: DL_DIR and SSTATE_DIR directories should have read and write permission.
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.
Build Commands$ petalinux-build $ petalinux-build --sdk
If you are building without network access then set the BB_NO_NETWORK variable.
Set BB_NO_NETWORK$ petalinux-config ---> Yocto Settings ---> [*] Enable BB NO NETWORK
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.