SMARC-sAMX7 User Guide. Rev. 1.9
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7.4.3.
Watchdog – CPU Watchdog Control
The "watchdog" command is used to control the i.MX7 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> - kick watchdog and set timeout (0 = disable kicking)
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
[forcibly] reset default environment
env default [-f] var [...]
[forcibly] reset variable(s) to their default values
env delete [-f] var [...]
[forcibly] delete variable(s)
env edit name
edit environment variable
env exists name
tests for existence of variable
env print [-a | name ...]
print environment
env run var [...]
run commands in an environment variable
env save
save environment
env set [-f] name [arg ...]
However, the legacy commands for environment handling are still available:
"setenv",
"editenv",
"printenv"
"saveenv".
