Let's manage Linux with Systemd! | APS｜組み込み業界専門メディア

How to use the development environment
What is Systemd
How to auto-launch the app

How to use the development environment

For C/C++

If you are writing a program in C/C++, run Yocto’s environment variable setup script.

$ . /opt/poky/2.1.1/environment-setup-cortexa8hf-neon-poky-linux-gnueabi

The minimum command options are set in the environment variable CC to compile C or in the environment variable CXX to compile C++, so you can compile as follows
C example: a

Cの例：
$ $CC APS.c –o APS

C++ example:
$ $CXX APS.cc –o APS

Read here to learn more!

The case of the script

Linux supports many scripts such as Python, Perl, Shell Script, etc.

If you use these scripts, install each package in SMART.

What is Systemd

Systemd to manage the system

Systemd is a framework for managing Linux systems. It provides not only the system startup, which replaces the traditional init daemon, but also many basic OS features such as inter-process communication, device manager, logging, containers and bootloaders. Many Linux distributions, such as pre-installed Angstrom, use Systemd.

Build with Systemd enabled.

In the poky directory, the
$ . oe-init-build-env build.armv7

At the end of conf/local.conf
DISTRO_FEATURES_append = " systemd"
VIRTUAL-RUNTIME_init_manager = "systemd"
DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
VIRTUAL-RUNTIME_initscripts = "“
Add.

Build!
$ bitbake core-image-sato

Read here to learn more!

After building it, install it in SMART.

How to auto-launch the app

Systemd manages tasks in units of units. To auto-launch the app, register it as follows

aps-linux.service
[Unit]
Description=APS Linux sample script     # Transition to a state of waiting to wake up
[Service]
Type=oneshot                            # Specify how to manage it; oneshot will consider the app finished when it has finished running
ExecStart=/home/root/aps-linux.sh       # Specify the app to run
[Install]
WantedBy=multi-user.target              # Specify when to run the app

Save the unit file in /lib/systemd/system. Then run the following command to complete the autostart configuration.

$ systemctl daemon-reload
$ systemctl enable aps-linux

Read here to learn more about how to write unit files!

If you want to know more about the whole Systemd, read here!

Check to see if it’s auto-starting!

$ systemctl status aps-linux
● aps-linux.service - APS Linux sample script
   Loaded: loaded (/lib/systemd/system/aps-linux.service; enabled; vendor preset: enabled)
   Active: activating (start) since Fri 2015-10-09 11:49:00 UTC; 21s ago
 Main PID: 1221 (aps-linux.sh)
   CGroup: /system.slice/aps-linux.service
           ├─1221 /bin/sh /home/root/aps-linux.sh
           └─1280 sleep 60

Oct 09 11:49:00 atlas systemd[1]: Starting APS Linux sample script...

After 60 seconds
$ systemctl status aps-linux
● aps-linux.service - APS Linux sample script
   Loaded: loaded (/lib/systemd/system/aps-linux.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Fri 2015-10-09 11:50:01 UTC; 28s ago
  Process: 1221 ExecStart=/home/root/aps-linux.sh (code=exited, status=0/SUCCESS)
 Main PID: 1221 (code=exited, status=0/SUCCESS)

Oct 09 11:49:00 atlas systemd[1]: Starting APS Linux sample script...
Oct 09 11:50:01 atlas systemd[1]: Started APS Linux sample script.

aps-linux.sh

#!/bin/sh

cd /sys/class/leds/fpga_led0
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led1
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led2
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led3
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led4
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led5
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led6
echo timer > trigger
sleep 0.1

cd /sys/class/leds/fpga_led7
echo timer > trigger
sleep 60

Cyclone V SoC-equipped board by Altera

The Altera SoC integrates an Arm-based hard processor system (HPS) consisting of processor, peripherals and memory interfaces with a customizable FPGA fabric on a high-bandwidth interconnector backbone. The hard IP includes PCI Express Gen2, multi-memory ports, ECC, memory protection and high-speed serial transceivers, combining features of low performance and power consumption with programmable logic flexibility. It significantly reduces the system board size, which previously consisted of a CPU and FPGA. In this course, the DE0-Nano-SoC Kit/Atlas-SoC Kit from Terasic will be used.
Japan Altera Corporation

TRACE32 made by Lauterbach

The world’s most used hardware-assisted debugger, TRACE32, which supports more than 70 processor architectures, not to mention Arm as well as Nios II. The multicore support of SMP systems allows you to control multiple cores simultaneously and to use the reference core as a Debugging can proceed seamlessly while switching between them. Another feature is the OS recognition function, which supports debugging of SMP-compatible operating systems such as Linux, as standard equipment. This allows you to smoothly debug a program running in user space without worrying about which core the task to be debugged is assigned to.
Japan Roterbach Corporation