byteDEVKIT (Yocto 3.0)

Image

Where do you get the SD card image?

Device	Yocto Version	Download	Checksum (SHA256)
byteDEVKIT	Yocto 3.0.3	bytesatwork-minimal-image-bytedevkit.wic.gz (wic.bmap)	1c1d442ef80de24f3bb02704880cf8c2124c88008aefca0264bf5850bdf7b54b

Hint

Updating from an older image? You can update your older image by using: apt-get update and apt-get upgrade.

1. check for new version in the table above

2. edit /etc/apt/sources.list and point to the new package feed

3. run apt-get update; apt-get upgrade

As the yocto framework is based on several packages from various projects or suppliers, it is not guaranteed that an incremental upgrade by apt-get upgrade works automatically. Some manual adjustments might be needed.

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How do you flash the image?

Attention

• You need a microSD card with at least 8GB capacity.

• All existing data on the microSD card will be lost.

• Do not format the microSD card before flashing.

Windows

1. Unzip the file bytesatwork-minimal-image-bytedevkit.wic.gz (e.g. with 7-zip)

2. Write the resulting file to the microSD card with a tool like Roadkils Disk Image

Linux

gunzip -c bytesatwork-minimal-image-bytedevkit.wic.gz | dd of=/dev/mmcblk<X> bs=8M conv=fdatasync status=progress

Hint

To improve write performance, you could use bmap-tools under Linux:

bmaptool copy bytesatwork-minimal-image-bytedevkit.wic.gz /dev/mmcblk<X>

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How do you build an image?

Use repo to download all necessary repositories:

$ mkdir -p ~/workdir/bytedevkit/3.0; cd ~/workdir/bytedevkit/3.0
$ repo init -u https://github.com/bytesatwork/bsp-platform-st.git -b zeus
$ repo sync

If those commands are completed successfully, the following command will set up a Yocto Project environment for byteDEVKIT:

$ cd ~/workdir/bytedevkit/3.0
$ MACHINE=bytedevkit DISTRO=poky-bytesatwork EULA=1 . setup-environment build

The final command builds the development image:

$ cd $BUILDDIR
$ bitbake bytesatwork-minimal-image

The output is found in:

~/workdir/bytedevkit/3.0/build/tmp/deploy/images/bytedevkit

Hint

For additional information about yocto images and how to build them, please visit: https://www.yoctoproject.org/docs/3.0/mega-manual/mega-manual.html#brief-building-your-image

How to modify the image

The image recipes can be found in ~/workdir/<machine name>/<yocto version>/sources/meta-bytesatwork/recipes-core/images

This is relative to where you started the repo command to fetch all the sources.

Edit the minimal-image recipe bytesatwork-minimal-image.bb

Add the desired software-package to IMAGE_INSTALL variable, for example add net-tools to bytesatwork-minimal-image.bb

Rebuild the image by:

$ cd ~/workdir/<machine name>/<yocto version>
$ MACHINE=<machine name> DISTRO=poky-bytesatwork EULA=1 . setup-environment build
$ bitbake bytesatwork-minimal-image

How to rename the image

If you want to rename or copy an image, simply rename or copy the image recipe by:

$ cd ~/workdir/<machine name>/<yocto version>/build/tmp/deploy/images/<machine name>
$ cp bytesatwork-minimal-image.bb customer-example-image.bb

Troubleshooting

• Image size is too small

  If you encounter that your image size is too small to install additional software, please have a look at the IMAGE_ROOTFS_SIZE variable under ~/workdir/<machine-name>/<yocto version>/sources/meta-bytesatwork/recipes-core/images/bytesatwork-minimal-image.bb. Increase the size if necessary.

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Toolchain

Where do you get the toolchain?

Device	Yocto Version	Download	Checksum (SHA256)
byteDEVKIT	Yocto 3.0.3	poky-bytesatwork-glibc-x86_64-bytesatwork-minimal-image-cortexa7t2hf-neon-vfpv4-bytedevkit-toolchain-3.0.3.sh	fe182429d8bf6d91ca2a556452894612b273141fd168af5bdf0add9be7c0573c

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How do you install the toolchain?

Simply download the toolchain and execute the downloaded file, which is a self-extracting shell script.

Hint

If you encounter problems when trying to install the toolchain, make sure the downloaded toolchain is executable. Run chmod +x /<path>/<toolchain-file>.sh to make it executable.

Important

The following tools need to be installed on your development system:

• xz (Debian package: xz-utils)

• python (any version)

• gcc

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How do you use the toolchain?

Source the installed toolchain:

source /opt/poky-bytesatwork/3.0.3/environment-setup-cortexa7t2hf-neon-vfpv4-poky-linux-gnueabi

Check if Cross-compiler is available in environment:

echo $CC

You should see the following output:

arm-poky-linux-gnueabi-gcc -mthumb -mfpu=neon-vfpv4 -mfloat-abi=hard -mcpu=cortex-a7 -fstack-protector-strong -D_FORTIFY_SOURCE=2 -Wformat -Wformat-security -Werror=format-security --sysroot=/opt/poky-bytesatwork/3.0.3/sysroots/cortexa7t2hf-neon-vfpv4-poky-linux-gnueabi

Crosscompile the source code, e.g. by:

$CC helloworld.c -o helloworld

Check generated binary:

file helloworld

The output that is shown in prompt afterwards:

helloworld: ELF 32-bit LSB pie executable, ARM, EABI5 version 1

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How to bring your binary to the target?

1. Connect the embedded device’s ethernet to your LAN

2. Determine the embedded target IP address by ip addr show

3. Copy your binary, e.g. helloworld to the target by scp helloworld root@<ip address of target>:/tmp

4. Run chmod +x on the target to make your binary executable: chmod +x /<path>/<binary name>

5. Run your binary on the target: /<path>/<binary name>

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How do you build a toolchain?

$ cd ~/workdir/bytedevkit/3.0
$ repo init -u https://github.com/bytesatwork/bsp-platform-st.git -b zeus
$ repo sync

If those commands are completed successfully, the following command will set up a Yocto Project environment for byteDEVKIT:

$ cd ~/workdir/bytedevkit/3.0
$ MACHINE=bytedevkit DISTRO=poky-bytesatwork EULA=1 . setup-environment build

The final command builds an installable toolchain:

$ cd $BUILDDIR
$ bitbake bytesatwork-minimal-image -c populate_sdk

The toolchain is located under:

~/workdir/bytedevkit/3.0/build/tmp/deploy/sdk

How to modify your toolchain

Currently the bytesatwork toolchain is generated out of the bytesatwork-minimal-image recipe. If you want to add additional libraries and development headers to customize the toolchain, you need to modify the bytesatwork-minimal-image recipe. It can be found under ~/workdir/<machine name>/<yocto version>/sources/meta-bytesatwork/recipes-core/images

For example if you want to develop your own ftp client and you need libftp and the corresponding header files, edit the recipe bytesatwork-minimal-image.bb and add ftplib to the IMAGE_INSTALL variable.

This will provide the ftplib libraries and development headers in the toolchain. After adding additional software components, the toolchain needs to be rebuilt by:

$ cd ~/workdir/<machine name>/<yocto version>
$ MACHINE=<machine> DISTRO=poky-bytesatwork EULA=1 . setup-environment build
$ bitbake bytesatwork-minimal-image -c populate_sdk

The newly generated toolchain will be available under:

~/workdir/<machine name>/<yocto version>/build/tmp/deploy/sdk

For additional information, please visit: https://www.yoctoproject.org/docs/3.0.3/overview-manual/overview-manual.html#cross-development-toolchain-generation

Kernel

Download the Linux Kernel

Device	Branch	git URL
byteDEVKIT	baw-v4.19-stm32mp	https://github.com/bytesatwork/linux-stm32mp.git

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Build the Linux Kernel

For both targets, an ARM toolchain is necessary. You can use the provided toolchain from Where do you get the toolchain? or any compatible toolchain (e.g. from your distribution)

Important

The following tools need to be installed on your development system:

• git

• make

• bc

Note

The following instructions assume, you installed the provided toolchain for the respective target.

Important

The following tools need to be installed on your development system:

• OpenSSL headers (Debian package: libssl-dev)

• depmod (Debian package: kmod)

1. Download kernel sources

   Download the appropriate kernel from Download the Linux Kernel.

2. Source toolchain

   source /opt/poky-bytesatwork/3.0.3/environment-setup-cortexa7t2hf-neon-vfpv4-poky-linux-gnueabi
   

3. Create defconfig

   make multi_v7_defconfig
   scripts/kconfig/merge_config.sh -m -r .config arch/arm/configs/fragment-*
   make olddefconfig
   

4. Build Linux kernel

   make LOADADDR=0xC2000040 -j `nproc` uImage stm32mp157c-bytedevkit-v1-1.dtb modules
   

5. Install kernel and device tree

   To use the newly created kernel, device tree and/or module, the necessary files need to be installed on the target. This can be done either via Ethernet (e.g. scp) or by copying the files to the SD card.

   Note

   For scp installation: Don’t forget to mount /boot on the target.

   File	Target path	Target partition
   arch/arm/boot/uImage	/boot/uImage	/dev/mmcblk0p4
   arch/arm/boot/dts/stm32mp157c-bytedevkit-v1-1.dtb	/boot/stm32mp157c-bytedevkit.dtb	/dev/mmcblk0p4

   Note

   After installing a new kernel, it often fails to load modules, as the _signature_ of the kernel changed and it fails to find its corresponding modules folder. This issue can often be resolved with a symlink:

   ln -s /lib/modules/<EXISTING FOLDER> /lib/modules/`uname -r`
   

   Otherwise, please follow the instructions to copy the kernel modules

6. Install kernel modules

   To copy all available modules to the target, it’s best to deploy them locally first and then copy all modules to the target.

   mkdir /tmp/bytedevkit
   make INSTALL_MOD_PATH=/tmp/bytedevkit modules_install
   

Now you can copy the content of the folder /tmp/bytedevkit into the target’s root folder (/) which is partition /dev/mmcblk0p5.