An instability counter is used to detect system instability.

• If 16 consecutive reboots are detected due to a watchdog, a “backup restore” operation is triggered.
• If 32 consecutive reboots are detected due to a watchdog, a “stock restore” operation is triggered.

The counter is reset if the system is up during at least 10 minutes. This feature cannot be disabled as it avoids bricking the gateway in case of software failure.

The counter bootfail is displayed at boot time only if the reboot is due to a watchdog. Bootcause information are available here.

Bootcause - Example

U-Boot 2015.04 (Aug 21 2018 - 18:53:11)

CPU:   Freescale i.MX6SX rev1.2 at 792 MHz
CPU:   Temperature 48 C
Reset cause: WDOG
       Watchdog enabled
I2C:   ready
DRAM:  240 MiB
MMC:   FSL_SDHC: 0
Using default environment

In:    serial
Out:   serial
Err:   serial
bootcause = SW
bootcount = 32
bootfail = 0
bootmode = nominal
boardconfig = 0x0
Net:   FEC0
Normal Boot

Packages installed during an update could make the system unstable, therefore, they are not immediately included in the backup.
There will be included the next time an update is triggered. Before each update, a snapshot of the firmware is done. It contains all the previously installed packages.
This snapshot is used if a “backup restore” is triggered.
If a backup recovery is triggered, only the stored packages are restored. Other packages are discarded.

Modifications in rootfs will be lost except system upgrade files.

This mecanism is divided in 2 elements:

• /etc/sysupgrade.conf: Contains the system (KerOS) elements to backup/restore.
• /etc/sysupgrade.d/: a directory with .conf files where additional elements to backup/restore can be added (i.e. by additional packages).

By default, some system configuration files are backed up like the network configuration.

To trigger a backup restore execute the following commands:

kerosd -b
reboot

The stock firmware is backuped at production time (or when updated with a KerOS liveburner.ipk file).
A “stock restore” will factory reset the station. All data will be lost. To trigger a stock restore execute the following commands:

kerosd -s 
reboot

Since firmware >= 4.1, a “stock restore” can also be triggered manually without console access.
To manually trigger a stock restore on Wirnet iBTS or iStation, please follow this procedure:

1. Unpower the gateway by pushing ON/OFF button more than 5 seconds
2. Make sure Power led is off and release button
3. Push On/OFF button to power-up the gateway and maintain until power and status leds blink alternatively. At this step, the gateway is ready to execute a stock restore operation. It will wait for a confirmation during 10 seconds
4. Release button and push it again to confirm the operation (leds will then stop blinking alternatively)
5. Wait for the end of this operation (Leds behavior described here). It takes approximately 2 minutes

To manually trigger a stock restore on Wirnet iFemtocell, please follow this procedure:

1. Push WPS button and maintain it
2. Push Reset button one second
3. At this step, the gateway is ready to execute a stock restore operation. It will wait for a confirmation during 10 seconds
4. Release WPS button and push it again to confirm the operation (leds will then stop blinking alternatively)
5. Wait for the end of this operation (Leds behavior described here). It takes approximately 2 minutes

This functionality from firmware < 4.0 must not be used to store configuration files. In order to save configuration use the sysupgrade management.