1、fw_printenv/fw_setenv
u-boot提供fw_printenv/fw_setenv 为Linux访问uboot环境编译。
在uboot端编译，在Linux端使用
2、测试环境
source /opt/fsl-imx-xwayland/4.14-sumo/environment-setup-aarch64-poky-linux
make envtools CC="$CC"
Now, you will find the u-boot/tools/env/fw_printenv
Note: the fw_setenv is applet of fw_printenv as busybox does
fw_env.config
fw_env.config default directory is in the /etc/
如下
/dev/mmcblk1 0x400000 0x2000
uboot/include/configs/imx8qxp_mek.h
0x2000 : #define CONFIG_ENV_SIZE 0x2000
0x400000 : #define CONFIG_ENV_OFFSET (64 * SZ_64K)
3、所有文件集成在rootfs里面
fw_env.config copy to /etc/
fw_printenv copy to /bin
Make symbol link fw_setenv from fw_printenv
ln -s fw_printenv fw_setenv
fw_setenv -> fw_printenv
4、Test fw_printenv/fw_setenv
注意以下文字，第一次开机的时候需要在uboot中设置saveenv
The first boot ， the environment is generated by uboot C code.
i.MX uboot detects the which board it is, then give proper u-boot environment
variables. It is in the memory not in the storage such as emmc, till you use
saveenv to do save.
If it is the first time to do the test, get into uboot run saveenv first.
Test fw_printenv/fw_setenv(Cont.)
Get in to linux then test fw_printenv
