6 Minimizing Boot Services Using init Script

The first program that starts after the Linux boot is /sbin/init, which can be replaced with a custom boot script. To replace /sbin/init, create a script first, then delete /sbin/init, and finally soft-link the custom script as the boot program using the ln -sf <your script> /sbin/init command.

The following is a reference script for CMS fast boot. This script ultimately launches the edgeai-tiovx-apps-main application. It first executes some mount commands to mount necessary partitions. It then loads several necessary modules using the modprobe command, including camera drivers, csi-rx, v4l2 (for camera data input), rpmsg (for communication with the AI DSP and the R-core that executes the ISP), tidss, and display_connecter (for display). After that, it exports some environment variables to prepare for the final run of services. Finally, it runs the edgeai-tiovx-apps-main executable program.

#!/bin/sh
set -x
export PATH=/usr/bin:/sbin:/bin
export LD_LIBRARY_PATH=/lib:/usr/lib:$LD_LIBRARY_PATH
mount -t proc proc /proc
mount -n -t sysfs sysfs /sys
mount -t debugfs debugfs /sys/kernel/debug
mount -t configfs configfs /sys/kernel/config
mount -t efivarfs efivarfs /sys/firmware/efi/efivars
mount -n -t tmpfs none /run
mount -n -t devtmpfs devtmpfs /dev
mkdir -p /dev/shm
chmod 1777 /dev/shm
mount -t tmpfs /dev/shm
export SOC=am62a
export DEVICE_NAME=AM62A
# Load essential kernel modules
insmod /lib/modules/6.6.58-ti-01497-ga7758da17c28-dirty/kernel/drivers/rpmsg/rpmsg_char.ko
insmod /lib/modules/6.6.58-ti-01497-ga7758da17c28-dirty/kernel/drivers/rpmsg/rpmsg_ctrl.ko
modprobe sii902x
modprobe tidss
modprobe display_connector
modprobe ti_k3_r5_remoteproc
modprobe ti_k3_dsp_remoteproc
modprobe omap_mailbox
modprobe cdns_csi2rx
modprobe j721e_csi2rx
modprobe v4l2_cci
modprobe videobuf2_dma_contig
modprobe v4l2_fwnode
modprobe videobuf2_memops
modprobe videobuf2_v4l2
modprobe videobuf2_common
modprobe v4l2_async
modprobe videodev
modprobe cdns_dphy_rx
modprobe mc
modprobe imx219
ulimit -c unlimited
echo "/tmp/core.%e.%p" > /proc/sys/kernel/core_pattern
export EDGEAI_GST_APPS_PATH=/opt/edgeai-gst-apps
export EDGEAI_DATA_PATH=/opt/edgeai-test-data
export OOB_DEMO_ASSETS_PATH=/opt/oob-demo-assets
export MODEL_ZOO_PATH=/opt/model_zoo
export EDGEAI_VERSION=10.1
export EDGEAI_SDK_VERSION=10_01_00
bash /opt/edgeai-gst-apps/scripts/setup_cameras.sh
./opt/edgeai-tiovx-apps/bin/Release/edgeai-tiovx-apps-main ./opt/edgeai-tiovx-apps/configs/linux/imx219_cam_example.yaml &
echo "System initialized: Hello world!!!!!!"
/bin/sh