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Yocto Linux for BeagleBone


Build and setup Yocto Kirkstone Linux image for BeagleBone


# Install dependencies
sudo apt-get install bc build-essential chrpath diffstat gawk git libncurses5-dev pkg-config socat subversion texi2html texinfo u-boot-tools liblz4-tool

# Clone yocto repo
git clone -b kirkstone

# Source build env
source poky/oe-init-build-env

# Build minimal image
MACHINE="beaglebone-yocto" bitbake core-image-full-cmdline

Boot up

# Setup sd card
1. make sure that sd card is empty
2. lsblk
  sdc           8:32   1    58G  0 disk
3. if not, sudo cfdisk /dev/sdc -> delete all partitions and write
4. eject the sd card and connect back in, check that the card is empty

# Flash image to beaglebone
cd tmp/deploy/images/beaglebone-yocto
sudo dd if=core-image-full-cmdline-beaglebone-yocto.wic of=/dev/sdc bs=4M

# Bootup linux
Eject sd card, connect it to beaglebone
Open serial console:
  gtkterm -p /dev/ttyUSB0 -s 115200
Press and hold the button near the sd card slot to boot from sd card, power up the beaglebone


SDK Setup
# Create extenesible sdk
bitbake core-image-full-cmdline -c populate_sdk_ext

# Install SDK
Set executable if it isn't already and run the script'

# set executable if it isn't already and run the script
chmod +x tmp/deploy/sdk/

# To change the install directory
./tmp/deploy/sdk/ -d /my/path/here

# SDK Usage
source /home/ton/beaglebone_os/sdk/test_sdk_full/environment-setup-cortexa8hf-neon-poky-linux-gnueabi

Yocto Recipes

Add new packages
# Example: Add recipe to the target image

# On target, htop missing
root@beaglebone-yocto:~# htop
-sh: htop: command not found

# Add new recipe to the sdk
devtool -d add --srcbranch main

# Try to build the recipe
devtool build htop

# Edit recipe
# Fix recipe by adding 'FILES:${PN} += "/usr/share/icons"' or in older yocto versions 'FILES_${PN} += "/usr/share/icons"'
devtool edit-recipe htop

# Deploy to the target
devtool deploy-target htop root@
Run new package on target device

At this point the binary is on the target, but shared libraries are missing

root@beaglebone-yocto:~# htop 
htop: error while loading shared libraries: cannot open shared object file: No such file or directory

If the recipe depends on other packages ( for example in htop: DEPENDS = "systemd libcap libnl xz" ) that are not on the target device yet, image needs to be built and deployed to target. Sdk gets updated with workdir recipe and it's dependencies, so the image can be built with devtool

devtool build-image

Alternatively, you can copy the runtime libs to the target: On the target, find out where the binary is located

root@beaglebone-yocto:~# find /usr/ -name "htop"

Cd to target root

cd /run/user/1000/gvfs/sftp:host=,user=root/home/root

Source sdk, if not sourced already

source ~/beaglebone_os/sdk/test_sdk_full/environment-setup-cortexa8hf-neon-poky-linux-gnueabi

Find dependencies

for file in $(arm-poky-linux-gnueabi-readelf -a /usr/bin/htop | \
grep "Shared library" | \
sed -nr '/Shared library:/ s/.*Shared library:([^"]+).*/\1/p' | \
tr -d "[]"); \
do name=$(echo $file | cut -d '.' -f 1) && find /home/ton/beaglebone_os/build/tmp/sysroots-components/cortexa8hf-neon -name $name.*; \
done \
> dependencies.txt

Copy libs to target

cat dependencies.txt | xargs -i sudo scp {} root@

Htop should now be usable on the target

  CPU[||||||                                                           7.1%] Tasks: 29, 1 thr, 64 kthr; 1 running
  Mem[||||||||||||||                                             30.1M/488M] Load average: 0.89 0.23 0.08 
  Swp[                                                                0K/0K] Uptime: 00:00:39

  [Main] [I/O]
  PID USER       PRI  NI  VIRT   RES   SHR S  CPU%-MEM%   TIME+  Command
  210 root        20   0  4036  3116  2356 R   2.6  0.6  0:00.22 htop
    1 root        20   0 10076  7188  5788 S   0.6  1.4  0:04.44 /sbin/init
  184 messagebus  20   0  4932  3116  2804 S   0.6  0.6  0:00.31 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activati
  133 rpc         20   0  3936  2248  2020 S   0.0  0.4  0:00.03 /usr/sbin/rpcbind -w -f

Apply the recipe to source tree

ton@mx-5:~/beaglebone_os/sdk/htop$ devtool finish htop ../../sources/meta-bbb/