swupdate.md

Over The Air (OTA) Updates

SWUpdate is used for providing OTA updates.

SWUpdate Configuration

• Build configuration: swupdate.config
• Runtime configuration: /etc/swupdate.cfg
  • Configuration documentation

SWUpdate Tools

The following client tools are included:

• Mongoose web server
• swupdate-client
• swupdate-progress
• swupdate-sysrestart
• swupdate-hawkbitcfg
• swupdate-sendtohawkbit

U-Boot Integration

U-Boot Environment

Key	Value	Description
bootcount	0..n	U-Boot feature
bootlimit	3	"
altbootcmd		"
upgrade_available	1	"
boot_system	A,B	Specifies the active system to boot

Boot Script

The U-Boot boot script uboot-boot.ush reads the environment variables and loads either system A or B.

Failed boot handling with bootcount > bootlimit is handled by U-Boot itself. If the bootlimit is reached, the altbootcmd is executed, which swaps the value in boot_system.

Linux Integration

Good Boot Verification

After a system update the boot up is monitored to determine if the update suceeded. The good boot is confirmed by the /usr/libexec/reset-bootcount.sh script and triggered by systemd app-update-bootcount.service and app-update-bootcount.timer:

• The good boot verification is only active if upgrade_available=1 is set.
• If the app is still running 3 minutes after boot up, then this is considered a succesful update.
• The systemd app.service has a watchdog configured, which reboots the system if the app is restarted more than twice within a minute.