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7.4.3. Watchdog – CPU Watchdog Control
The "watchdog" command is used to control the i.MX8X CPU internal watchdog. After watchdog has been started
using "watchdog start", the watchdog is kicked periodically by U-Boot to prevent expiration.
Watchdog timeout can be changed at any time. However, it is not possible to stop watchdog
once it has been started.
Syntax:
=> help watchdog
watchdog - start/stop/kick IMX watchdog
Usage:
watchdog <timeout>
watchdog start <timeout> - start watchdog and set timeout
Example:
Start watchdog with 5 seconds timeout and stop kicking watchdog some time later. Board will reset after watchdog
has been expired.
=> watchdog 5
=> watchdog 0
7.5. Bootloader Environment
The bootloader environment is used to control bootloader and OS startup behavior. Environment variables can be
used to control boot timing (e.g. bootdelay), interface properties (e.g. baudrate, ethact) or they define memory
locations where OS images are stored before boot (e.g. loadaddr, fdt_addr). In addition, bootloader shell commands
can be combined to environment scripts.
The redundant bootloader environment is permanently stored in the QSPI flash device at offset 0x0C0000 and
0x0C8000. During bootloader operation, the environment is held in RAM memory and can be modified and written
back to persistent storage.
Bootloader commands to modify the environment are summed up under the "env" command group:
env default [-f] –a
env default [-f] var [...]
env delete [-f] var [...]
env edit name
env exists name
env print [-a | name ...]
env run var [...]
env save
env set [-f] name [arg ...]
However, the legacy commands for environment handling are still available:
"setenv",
"editenv",
"printenv"
"saveenv".
www.kontron.com
- kick watchdog and set timeout (0 = disable kicking)
[forcibly] reset default environment
[forcibly] reset variable(s) to their default values
[forcibly] delete variable(s)
edit environment variable
tests for existence of variable
print environment
run commands in an environment variable
save environment
SMARC-sAMX8X User Guide. Rev. 1.1
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