Working with U-Boot tools requires that the environment has been saved with the saveenv command from U-Boot prompt, otherwise the U-Boot tools are using the default environment.
If redundant environment is configured the saveenv command must be executed twice to write the the second environment.
U-Boot provides two tools to read fw_setenv and edit fw_printenv the U-Boot environment from the Linux shell. The U-Boot tools are selected by default in the BSP's. This tutorial describes how to setup the configuration file and the usage of these tools.
The U-Boot Tools need a proper configuration in /etc/fw_env.config. The memory offset and environment size have to be configured in the config file.
In case of a unmanaged memory (e.g. SPI NOR) the block size also has to be configured. The example configurations below refers to the default partitioning of our BSP's.
TQMa7x
eMMC
# THIS IS VALID FOR TQMa7 eMMC only!
#eMMC Block device access
/dev/mmcblk0 0x100000 0x2000
# if using with redundant env
# /dev/mmcblk0 0x102000 0x2000
SD Card
# THIS IS VALID FOR TQMa7 SD-card only!
# eMMC Block device access
/dev/mmcblk1 0x100000 0x2000
# if using with redundant env
# /dev/mmcblk1 0x102000 0x2000
</code>
TQMa6UL
eMMC
# THIS IS VALID FOR TQMa6UL eMMC only!
# eMMC Block device access
/dev/mmcblk0 0x100000 0x2000
# if using with redundant env
# /dev/mmcblk0 0x102000 0x2000
SD Card
# THIS IS VALID FOR TQMa6UL SD-card only!
# eMMC Block device access
/dev/mmcblk1 0x100000 0x2000
# if using with redundant env
# /dev/mmcblk1 0x102000 0x2000
</code>
TQMa6x
# THIS IS VALID FOR TQMa6x eMMC only!
# eMMC Block device access
/dev/mmcblk0 0x100000 0x2000
# if using with redundant env
# /dev/mmcblk0 0x102000 0x2000
SD Card
# THIS IS VALID FOR TQMa6x SD-card only!
# eMMC Block device access
/dev/mmcblk1 0x100000 0x2000
# if using with redundant env
# /dev/mmcblk1 0x102000 0x2000
TQMa28
eMMC
# THIS IS VALID FOR TQMa28 eMMC only!
# eMMC Block device access
/dev/mmcblk0 0x400 0x1FC00
SD Card
# THIS IS VALID FOR TQMa28 SD-card only!
# eMMC Block device access
/dev/mmcblk1 0x400 0x1FC00
TQMLS102xA
eMMC and SD Card
# THIS IS VALID FOR TQMLS102xA SD-Card and eMMC!
# eMMC Block device access
/dev/mmcblk0 0x100000 0x8000
# if using with redundant env
/dev/mmcblk0 0x108000 0x8000
Read U-Boot Environment
Edit U-Boot Environment
fw_setenv [parameter] [value]
Example
This sets the value of the bootdelay paramter in your environment to 3
fw_setenv bootdelay 3