Building TI/Embedian’s Yocto BSP Distribution

Eric Lee

version 1.0a, 8/28/2016

Introduction

This document describes how Embedian builds a customized version of TI's AM335X official BSP release for Embedian's SMARC-T3354 product platform. The approach is to pull from Embedian's public facing GIT repository and build that using bitbake. The reason why we use this approach is that it allows co-development. The build output is comprised of binary images, feed packages, and an SDK for SMARC-T3354 specific development.

TI makes their Processor-SDK-03.00.00.04 Arago build scripts available via the following GIT repository:

http://arago-project.org/git/projects/oe-layersetup.git

If you’re interested in TI’s overall Processor SDK build and test process you should analyze the following repository:

http://arago-project.org/git/projects/tisdk-build-scripts.git

It is this repository that actually pulls in the oe-layersetup project to perform the Linux Processor-SDK builds for TI’s entire suite of ARM CortextA chips. In this document we are only concerned with the oe-layersetup project.

Generating SSH Keys

We recommend you use SSH keys to establish a secure connection between your computer and Embedian Gitlab server. The steps below will walk you through generating an SSH key and then adding the public key to our Gitlab account.

Step 1. Check for SSH keys

First, we need to check for existing ssh keys on your computer. Open up Git Bash and run:

Check the directory listing to see if you have a file named either id_rsa.pub or id_dsa.pub. If you don't have either of those files go to step 2. Otherwise, you already have an existing keypair, and you can skip to step 3.

Step 2. Generate a new SSH key

To generate a new SSH key, enter the code below. We want the default settings so when asked to enter a file in which to save the key, just press enter.

Now you need to enter a passphrase.

Which should give you something like this:

Step 3. Add your SSH key to Embedian Gitlab Server

Copy the key to your clipboard.

Go to Embedian Git Server. At Profile Setting --> SSH Keys --> Add SSH Key

Paste your public key and press "Add Key" and your are done.

Overview of the meta-smarct335x-sdk-03-00-00-04 Yocto Layer

The supplied meta-smarct335x-sdk-03-00-00-04 Yocto compliant layer has the following organization:

Notes on meta-smarct335x-sdk-03-00-00-04 layer content

conf/machine/*

This folder contains the machine definitions for the smarct335x platform and backup repository in Embedian. These select the associated kernel, kernel config, u-boot, u-boot config, and UBI image settings.

recipes-bsp/u-boot/*

This folder contains recipes used to build DAS U-boot for smarct335x platform.

recipes-connectivity/lftp/*

This folder adds lftp ftp client utility for smarct335x platform.

recipes-core/base-files/*

This recipe is used to amend the device hostname for the platform.

recipes-core/busybox/*

This recipe modifies TI’s BusyBox configuration to remove telnet from the image.

recipes-core/images/*

These recipes are used to create the final target images for the devices. When you run Bitbake one of these recipes would be specified. For example, to build the root file system for the smarct335x platform:

MACHINE=smarct335x bitbake -k smarct335x-rootfs-image

recipes-core/init-ifupdown*

This recipe is used to amend device network interfaces

recipes-devtools/nodejs/*

These recipes build the Node.js Javascript server execution environment.

recipes-kernel/linux/*

Contains the recipes needed to build the smarct335x Linux kernels.

recipes-support/boost/*

Adds Boost to the images. Boost provides various C++ libraries that encourage cross-platform development.

recipes-support/ntp/*

Network time protocol support.

recipes-tisdk/ti-tisdk-makefile/*

Add smarct335x device tree into Makefile.

Setting Up the Tools and Build Environment

To build the latest TI AM335X Processor-SDK-03-00-00-04, you first need an Ubuntu 14.04LTS or 16.04LTS installation. Because of support for 32-bit host is dropped as Linaro toolchain is available only for 64-bit machines., an x86_64 ubuntu 14.04 is highly recommended. Since bitbake does not accept building images using root privileges, please do not login as a root user when performing the instructions in this section.

Once you have Ubuntu 14.04LTS running, install the additional required support packages using the following console command:

$ sudo apt-get install gawk wget git-core diffstat unzip texinfo build-essential chrpath libsdl1.2-dev xterm python python-m2crypto bc dos2unix socat libsdl1.2-dev

If you are using a 64-bit Linux, then you'd also need to install 32-bit support libraries, needed by the pre-built Linaro toolchain and other binary tools.

$ sudo dpkg --add-architecture i386 $ sudo apt-get update $ sudo apt-get install curl g++-multilib gcc-multilib lib32z1-dev libcrypto++9:i386 libcrypto++-dev:i386 liblzo2-dev:i386 libusb-1.0-0:i386 libusb-1.0-0-dev:i386 uuid-dev:i386

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If you saw error like the following after running "sudo dpkg --add-architecture i386"

pkg: error: unknown option --add-architecture

make sure the only file present in /etc/dpkg/dpkg.cfg.d/ is "multiarch"

ls /etc/dpkg/dpkg.cfg.d/

if output is

multiarch

execute the following commands as it is else replace "multiarch" with the name of file present in that directory.

$ sudo sh -c "echo 'foreign-architecture i386' > /etc/dpkg/dpkg.cfg.d/multiarch"

The above command will add i386 architecture.

You’ll also need to change the default shell to bash from Ubuntu’s default dash shell (select the <No> option):

$ sudo dpkg-reconfigure dash

To build TI’s am335x Processor-SDK-03.00.00.04 you will need to install the Linaro arm compiler that TI used for the release:

$ wget https://releases.linaro.org/components/toolchain/binaries/5.3-2016.02/arm-linux-gnueabihf/gcc-linaro-5.3-2016.02-x86_64_arm-linux-gnueabihf.tar.xz

$ sudo tar -C /opt -xJf gcc-linaro-5.3-2016.02-x86_64_arm-linux-gnueabihf.tar.xz

Add the following PATH definition to the .bashrc file in your $HOME directory:

$ export PATH=/opt/gcc-linaro-5.3-2016.02-x86_64_arm-linux-gnueabihf/bin:$PATH

Next clone and intialize TI’s am335x SDK build process:

$ git clone http://arago-project.org/git/projects/oe-layersetup.git smarct3x-sdk-03.00.00.04 $ cd smarct3x-sdk-03.00.00.04 $ git checkout -b smarct3x-processor-sdk-03.00.00.04 8de372ee2f41c6bba32c532a712cc4c00be3a259 $ ./oe-layertool-setup.sh -f configs/processor-sdk/processor-sdk-03.00.00.04-config.txt

Add the Embedian’s meta-smarct335x-sdk-03-00-00-04 layer to the build process.

$ cd ~/smarct3x-sdk-03.00.00.04/sources $ git clone git@git.embedian.com:developer/meta-smarct335x-sdk-03-00-00-04.git $ cd ~/smarct3x-processor-sdk-03.00.00.04/build

Edit the ~/smarct3x-sdk-03.00.00.04/build/conf/bblayers.conf file to include the meta-smarct335x-sdk-03-00-00-04 layer in the layer list. It should look something like this (the example reflects the absolute paths on my machine):

# This template file was created by taking the oe-core/meta/conf/bblayers.conf
# file and removing the BBLAYERS section at the end.

# LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
# changes incompatibly
LCONF_VERSION = "7"

BBPATH = "${TOPDIR}"
BBFILES ?= ""

# Layers configured by oe-core-setup script
BBLAYERS += " \

 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-smarct335x-sdk-03-00-00-04 \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-processor-sdk \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-arago/meta-arago-distro \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-arago/meta-arago-extras \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-qt5 \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-openembedded/meta-networking \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-openembedded/meta-ruby \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-openembedded/meta-python \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-openembedded/meta-oe \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-ti \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/meta-linaro/meta-linaro-toolchain \
 /home/eric/smarct3x-sdk-03.00.00.04/sources/oe-core/meta \
"

Building the target platforms

To build the Embedian SMARC-T335X developer board images, respectively, use the following commands:

$ cd ~/smarct3x-sdk-03.00.00.04/build $ source conf/setenv $ MACHINE=smarct335x bitbake -k smarct335x-rootfs-image

Note

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The first clean build might take more than 10 hours. If you met errors during the building process, let it finish and usually build again should be fine.

Once it done, you can find all required images under ~/smarct3x-sdk-03.00.00.04/build/arago-tmp-external-linaro-toolchain/deploy/images/smarct335x/

You may want to build programs that aren’t installed into a root file system so you can make them available via a feed site (described below.) To do this you can build the package directly and then build the package named package-index to add the new package to the feed site.

The following example builds the minicom program and makes it available on the feed site:

$ MACHINE=smarct335x bitbake minicom $ MACHINE=smarct335x bitbake package-index

Once the build(s) are completed you’ll find the resulting images, feeds and licenses in folder ~/smarct3x-processor-sdk-03.00.00.04/build/arago-tmp-external-linaro-toolchain/deploy/

deploy/images/smarct335x/*

This folder contains the binary images for the root file system and the Embedian SMARC-T335X specific version of the am335X SDK. Specifically the images are:

deploy/images/smarct335x/u-boot.img

This u-boot bootloader binary for SMARC T335X

deploy/images/smarct335x/MLO

The "Stage 1 Boot Loader" for SMARC-T335X. Its purpose is load the Stage 2 Boot Loader (u-boot.img).

deploy/images/smarct335x/zImage

The kernel zImage for SMARC-T335X.

deploy/images/smarct335x/zImage-am335x-smarct335x.dtb

The device tree binary file for SMARC-T335X.

deploy/images/smarct335x/smarct335x-rootfs-image-smarct335x*

Embedian root file system images for software development on Embedian’s SMARC-T335X platforms.

deploy/ipk/*

This folder contains all the packages used to construct the root file system images. They are in opkg format (similar format to Debian packages) and can be dynamically installed on the target platform via a properly constructed feed file. Here is an example of the feed file (named base-feeds.conf) that is used internally at Embedian to install upgrades onto a smarct335x platform without reflashing the file system:

src/gz smarct335x http://www.embedian.com/core-sdk/smarct335x/processor-sdk-03.00.00.04/deploy/ipk/all

src/gz cortexa8hf-neon http://www.embedian.com/core-sdk/smarct335x/smarct3x-processor-sdk-03.00.00.04/deploy/ipk/cortexa8hf-neon

src/gz smarct335x http://www.embedian.com/core-sdk/smarct335x/smarct3x-processor-sdk-03.00.00.04/deploy/ipk/smarct335x

deploy/licenses/*

A database of all licenses used in all packages built for the system.

deploy/sdk/arago-2015.12-cortexa9-linux-gnueabi-tisdk.sh

The installer for ARM toolchain that was created for the target platform. In Embedian’s case that means that the headers for the Boost libraries are baked into the tools. (Generate by meta-toolchain-smarc-tisdk image)

Setup SD Card

For these instruction, we are assuming: DISK=/dev/mmcblk0, "lsblk" is very useful for determining the device id.

$ export DISK=/dev/mmcblk0

Erase SD card:

$ sudo dd if=/dev/zero of=${DISK} bs=1M count=16

Create Partition Layout:

With util-linux v2.26, sfdisk was rewritten and is now based on libfdisk.

sfdisk

$ sudo sfdisk --version

sfdisk from util-linux 2.27.1

Create Partitions:

sfdisk >=2.26.x

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$ sudo sfdisk ${DISK} <<-__EOF__
1M,48M,0xE,*
,,,-
__EOF__

sfdisk <=2.25

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$ sudo sfdisk --in-order --Linux --unit M ${DISK} <<-__EOF__
1,48,0xE,*
,,,-
__EOF__

Format Partitions:

for: DISK=/dev/mmcblk0
$ sudo mkfs.vfat -F 16 ${DISK}p1 -n boot
$ sudo mkfs.ext4 ${DISK}p2 -L rootfs
 
for: DISK=/dev/sdX
$ sudo mkfs.vfat -F 16 ${DISK}1 -n boot
$ sudo mkfs.ext4 ${DISK}2 -L rootfs

Mount Partitions:

On some systems, these partitions may be auto-mounted...

$ sudo mkdir -p /media/boot/
$ sudo mkdir -p /media/rootfs/
 
for: DISK=/dev/mmcblk0
$ sudo mount ${DISK}p1 /media/boot/
$ sudo mount ${DISK}p2 /media/rootfs/
 
for: DISK=/dev/sdX
$ sudo mount ${DISK}1 /media/boot/
$ sudo mount ${DISK}2 /media/rootfs/

Install Bootloader

Copy MLO/u-boot.img to the boot partition

deploy/images

$ sudo cp -v MLO /media/boot/

$ sudo cp -v u-boot.img /media/boot/

uEnv.txt based bootscript

Create "uEnv.txt" boot script: (vim uEnv.txt)

~/uEnv.txt

optargs="consoleblank=0 mem=512M"
#u-boot eMMC specific overrides; Angstrom Distribution (SMARC-T335X) 2014-05-20
kernel_file=zImage
initrd_file=initrd.img

loadaddr=0x82000000
initrd_addr=0x88080000
fdtaddr=0x88000000
fdtfile=am335x-smarct335x.dtb

initrd_high=0xffffffff
fdt_high=0xffffffff

loadimage=load mmc ${mmcdev}:${mmcpart} ${loadaddr} ${kernel_file}
loadinitrd=load mmc ${mmcdev}:${mmcpart} ${initrd_addr} ${initrd_file}; setenv initrd_size ${filesize}
loadfdt=load mmc ${mmcdev}:${mmcpart} ${fdtaddr} /dtbs/${fdtfile}
#

##Un-comment to enable systemd in Debian Wheezy
#optargs=quiet init=/lib/systemd/systemd

console=ttyS3,115200n8
mmcroot=/dev/mmcblk1p2 ro
mmcrootfstype=ext4 rootwait fixrtc

mmcargs=setenv bootargs console=${console} root=${mmcroot} rootfstype=${mmcrootfstype} ${optargs}

#zImage:
uenvcmd=run loadimage; run loadfdt; run mmcargs; bootz ${loadaddr} - ${fdtaddr}

#zImage + uInitrd: where uInitrd has to be generated on the running system.
#boot_fdt=run loadimage; run loadinitrd; run loadfdt
#uenvcmd=run boot_fdt; run mmcargs; bootz ${loadaddr} ${initrd_addr}:${initrd_size} ${fdtaddr}

###Begin Rootfs from NFS
#serverip=192.168.1.51
#rootpath=/srv/nfs/smarct335x/ubuntu1204/
#nfsopts=nolock,acdirmin=60
#netargs=setenv bootargs console=${console} ${optargs} root=/dev/nfs nfsroot=${serverip}:${rootpath},${nfsopts} rw ip=dhcp
##netboot=echo Loading kernel from SDCARD and booting from NFS ...; run loadimage; run netargs; bootz ${loadaddr} - ${fdtaddr}
##uenvcmd=run netboot
###End Rootfs from NFS

###Begin Load kernel from TFTP
#netmask=255.255.255.0
#ipaddr=192.168.1.65
#serverip=192.168.1.51
#netboot=echo Loading kernel and device tree from TFTP and booting from NFS ...; setenv autoload no; tftp ${loadaddr} ${kernel_file}; tftp ${fdtaddr} ${fdtfile}; run netargs; bootz ${loadaddr} - ${fdtaddr}
#uenvcmd=run netboot
###End Load kernel from TFTP

Install Kernel zImage

Copy zImage to the boot partition:

build/arago-tmp-external-linaro-toolchain/deploy/images/smarct335x

$ sudo cp -v zImage /media/boot

Install Kernel Device Tree Binary

build/arago-tmp-external-linaro-toolchain/deploy/images/smarct335x

$ sudo mkdir -p /media/boot/dtbs

$ sudo cp -v zImage-am335x-smarct335x.dtb /media/boot/dtbs/am335x-smarct335x.dtb

Install Root File System and Kernel Modules

build/arago-tmp-external-linaro-toolchain/deploy/images/smarct437x

$ sudo tar xvfz smarct335x-rootfs-image-smarct335x.tar.gz -C /media/rootfs

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Kernel modules are built into root filesystems.

Remove SD card:

$ sync
$ sudo umount /media/boot
$ sudo umount /media/rootfs

Setup eMMC

Setting up eMMC usually is the last step at development stage after the development work is done at your SD card or NFS environments. eMMC on module will be always emulated as /dev/mmcblk0. Setting up eMMC now is nothing but changing the device descriptor.

This section gives a step-by-step procedure to setup eMMC flash. Users can write a shell script your own at production to simplify the steps.

First, we need to backup the final firmware from your SD card or NFS.

Prepare for eMMC binaries from SD card (or NFS):

Insert SD card into your Linux PC. For these instructions, we are assuming: DISK=/dev/mmcblk0, "lsblk" is very useful for determining the device id.

For these instruction, we are assuming: DISK=/dev/mmcblk0, "lsblk" is very useful for determining the device id.

$ export DISK=/dev/mmcblk0

Mount Partitions:

On some systems, these partitions may be auto-mounted...

$ sudo mkdir -p /media/boot/
$ sudo mkdir -p /media/rootfs/
 
for: DISK=/dev/mmcblk0
$ sudo mount ${DISK}p1 /media/boot/
$ sudo mount ${DISK}p2 /media/rootfs/
 
for: DISK=/dev/sdX
$ sudo mount ${DISK}1 /media/boot/
$ sudo mount ${DISK}2 /media/rootfs/

Copy MLO to rootfs partition:

$ sudo cp -v /media/boot/MLO /media/rootfs/home/root

Copy u-boot.img to rootfs partition:

$ sudo cp -v /media/boot/u-boot.img /media/rootfs/home/root

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The U-Boot for eMMC Boot up has one line difference in include/configs/smarct335x_evm.h. The mmcdev in SD boop up is 0 and is 1 in eMMC boot up. Please go to

recipes-bsp/u-boot/u-boot-smarct335x_2016.05-smarct335x.bb and make changes as follows.

BRANCH = "v2016.05-smarct3x"

SRCREV = "cd7520d6afe9ed5916619394538aabb56a738378"

# If Boot up from on module eMMC
# BRANCH = "v2016.05-smarct3x-emmc"

# SRCREV = "b08695ae0d33b53b1c44e001fddc542497d2f7e6"

Copy zImage to rootfs partition:

arago-tmp-external-linaro-toolchain/deploy/images

$ sudo cp -v zImage /media/rootfs/home/root

Copy uEnv.txt to rootfs partition:

Copy and paste the following contents to /media/rootfs/home/root ($ sudo vim /media/rootfs/home/root/uEnv.txt)

optargs="consoleblank=0 mem=512M"
#u-boot eMMC specific overrides; Angstrom Distribution (SMARC T335X) 2014-05-20
kernel_file=zImage
initrd_file=initrd.img
loadaddr=0x82000000
initrd_addr=0x88080000
fdtaddr=0x88000000
fdtfile=am335x-smarct335x.dtb
initrd_high=0xffffffff
fdt_high=0xffffffff
loadimage=load mmc ${mmcdev}:${mmcpart} ${loadaddr} ${kernel_file}
loadinitrd=load mmc ${mmcdev}:${mmcpart} ${initrd_addr} ${initrd_file}; setenv initrd_size ${filesize}
loadfdt=load mmc ${mmcdev}:${mmcpart} ${fdtaddr} /dtbs/${fdtfile}
#
##Un-comment to enable systemd in Debian Wheezy
#optargs=quiet init=/lib/systemd/systemd
console=ttyS3,115200n8
#mmcroot=/dev/mmcblk0p2 ro
#mmcrootfstype=ext4 rootwait fixrtc
mmcroot=/dev/ram0
#mmcargs=setenv bootargs console=${console} root=${mmcroot} rootfstype=${mmcrootfstype} ${optargs}
mmcargs=setenv bootargs console=${console} root=${mmcroot} initramfs=0x81000000, 8M
#zImage:
uenvcmd=run loadimage; run loadfdt; run mmcargs; bootz ${loadaddr} - ${fdtaddr}
#zImage + uInitrd: where uInitrd has to be generated on the running system.
#boot_fdt=run loadimage; run loadinitrd; run loadfdt
#uenvcmd=run boot_fdt; run mmcargs; bootz ${loadaddr} ${initrd_addr}:${initrd_size} ${fdtaddr}
###Begin Rootfs from NFS
#serverip=192.168.1.51
#rootpath=/srv/nfs/smarct335x/ubuntu1204/
#nfsopts=nolock,acdirmin=60
#netargs=setenv bootargs console=${console} ${optargs} root=/dev/nfs nfsroot=${serverip}:${rootpath},${nfsopts} rw ip=dhcp
##netboot=echo Loading kernel from SDCARD and booting from NFS ...; run loadimage; run netargs; bootz ${loadaddr} - ${fdtaddr}
##uenvcmd=run netboot
###End Rootfs from NFS
###Begin Load kernel from TFTP
#netmask=255.255.255.0
#ipaddr=192.168.1.65
#serverip=192.168.1.51
#netboot=echo Loading kernel and device tree from TFTP and booting from NFS ...; setenv autoload no; tftp ${loadaddr} ${kernel_file}; tftp ${fdtaddr} ${fdtfile}; run netargs; bootz ${loadaddr} - ${fdtaddr}
#uenvcmd=run netboot
###End Load kernel from TFTP

Copy real rootfs to rootfs partition:

$ pushd /media/rootfs

$ sudo tar cvfz ~/smarct335x-emmc-rootfs.tar.gz .

$ sudo mv ~/smarct335x-emmc-rootfs.tar.gz /media/rootfs/home/root

$ popd

Remove SD card:

$ sync
$ sudo umount /media/boot
$ sudo umount /media/rootfs

Insert this SD card into your SMARC T335X device and boot up from SD card.

Now it will be almost the same as you did when setup your SD card, but the eMMC device descriptor is /dev/mmcblk1 now.

$ export DISK=/dev/mmcblk0

Erase SD card:

$ sudo dd if=/dev/zero of=${DISK} bs=1M count=16

Create Partition Layout:

$ sudo sfdisk --in-order --Linux --unit M ${DISK} <<-__EOF__
1,48,0xE,*
,,,-
__EOF__

Format Partitions:

$ sudo mkfs.vfat -F 16 ${DISK}p1 -n boot

$ sudo mkfs.ext4 ${DISK}p2 -L rootfs

Mount Partitions:

$ sudo mkdir -p /media/boot/
$ sudo mkdir -p /media/rootfs/
$ sudo mount ${DISK}p1 /media/boot/
$ sudo mount ${DISK}p2 /media/rootfs/

Install binaries for partition 1

Copy MLO/u-boot.img/uEnv.txt/zImage to the boot partition

$ sudo cp -v MLO u-boot.img zImage uEnv.txt /media/boot/

Install Kernel Device Tree Binary

$ sudo mkdir -p /media/boot/dtbs

$ sudo cp -v am335x-smarct335x.dtb /media/boot/dtbs

Install Root File System

$ sudo tar -zxvf smarct335x-emmc-rootfs.tar.gz -C /media/rootfs

Unmount eMMC:

$ sync
$ sudo umount /media/boot
$ sudo umount /media/rootfs

Switch your Boot Select to eMMC and you will be able to boot up from eMMC now.

Feed Packages

The following procedure can be used on a Embedian SMARC-T335X device to download and utilize the feed file show above to install the minicom terminal emulation program:

# vim /etc/opkg/base-feeds.conf

Only keep the following three lines:

src/gz all http://www.embedian.com/core-sdk/smarct335x/smarct3x-processor-sdk-03.00.00.04/deploy/ipk/all
src/gz cortexa8hf-neon http://www.embedian.com/core-sdk/smarct335x/smarct3x-processor-sdk-03.00.00.04/deploy/ipk/cortexa8hf-neon
src/gz smarct335x http://www.embedian.com/core-sdk/smarct335x/smarct3x-processor-sdk-03.00.00.04/deploy/ipk/smarct335x

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# opkg update

# opkg upgrade

# opkg install minicom

Writing Bitbake Recipes

In order to package your application and include it in the root filesystem image, you must write a BitBake recipe for it.

When starting from scratch, it is easiest to learn by example from existing recipes.

Example HelloWorld recipe using autotools

For software that uses autotools (./configure; make; make install), writing recipes can be very simple:

SRC_URI specifies the location to download the source from. It can take the form of any standard URL using http://, ftp://, etc. It can also fetch from SCM systems, such as git in the example above.

PR is the package revision variable. Any time a recipe is updated that should require the package to be rebuilt, this variable should be incremented.

inherit autotools brings in support for the package to be built using autotools, and thus no other instructions on how to compile and install the software are needed unless something needs to be customized.

S is the source directory variable. This specifies where the source code will exist after it is fetched from SRC_URI and unpacked. The default value is ${WORKDIR}/${PN}-${PV}, where PN is the package name and PV is the package version. Both PN and PV are set by default using the filename of the recipe, where the filename has the format PN_PV.bb.

Example HelloWorld recipe using a single source file

This example shows a simple case of building a helloworld.c file directly using the default compiler (gcc). Since it isn’t using autotools or make, we have to tell BitBake how to build it explicitly.

In this case, SRC_URI specifies a file that must exist locally with the recipe. Since there is no code to download and unpack, we set S to WORKDIR since that is where helloworld.c will be copied to before it is built.

WORKDIR is located at ${OETREE}/build/arago-tmp-external-linaro-toolchain/work/cortexa8hf-vfp-neon-linux-gnueabi/<package name and version> for most packages. If the package is machine-specific (rather than generic for the armv7ahf architecture), it may be located in the smarct335x-linux-gnueabi subdirectory depending on your hardware (this applies to kernel packages, images, etc).

do_compile defines how to compile the source. In this case, we just call gcc directly. If it isn’t defined, do_compile runs make in the source directory by default.

do_install defines how to install the application. This example runs install to create a bin directory where the application will be copied to and then copies the application there with permissions set to 755.

D is the destination directory where the application is installed to before it is packaged.

${bindir} is the directory where most binary applications are installed, typically /usr/bin.

For a more in-depth explanation of BitBake recipes, syntax, and variables, see the Recipe Chapter of the OpenEmbedded User Manual.

-- End of Document --

version 1.0a, 08/28/2016

Last updated 2016-08-28

SMARC T3354 ProcessorSDK03000004

Building TI/Embedian’s Yocto BSP Distribution

Introduction

Generating SSH Keys

Step 1. Check for SSH keys

Step 2. Generate a new SSH key

Step 3. Add your SSH key to Embedian Gitlab Server

Overview of the meta-smarct335x-sdk-03-00-00-04 Yocto Layer

Setting Up the Tools and Build Environment

Building the target platforms

Setup SD Card

Install Bootloader

uEnv.txt based bootscript

Install Kernel zImage

Install Kernel Device Tree Binary

Install Root File System and Kernel Modules

Setup eMMC

Prepare for eMMC binaries from SD card (or NFS):

Install binaries for partition 1

Install Kernel Device Tree Binary

Install Root File System

Feed Packages

Writing Bitbake Recipes

Example HelloWorld recipe using autotools

Example HelloWorld recipe using a single source file