topic Re: Access u-boot varibale from linux user space in i.MX Processors

Access u-boot varibale from linux user space

kartheek — Tue, 16 Dec 2025 10:54:13 GMT

Hi,

Processor: IMX8M PLUS

Yocto : 5.15-kirkstone

While booting through SD card able to access fw_printenv/setenv by adding below line in image recipe of yocto build.

IMAGE_INSTALL += " u-boot-fw-utils"

u-boot configuration is as below.

CONFIG_ENV_SIZE=0x80000 CONFIG_ENV_OFFSET=0x380000 CONFIG_ENV_IS_NOWHERE=y CONFIG_ENV_IS_IN_MMC=y CONFIG_SYS_MMC_ENV_DEV=1 CONFIG_SYS_MMC_ENV_PART=0

But when executing those commands on target gives below error.

~# fw_printenv Configuration file wrong or corrupted

Kindly suggest a procedure to make fw_printenv/setenv work.

Thanks,
Kartheek

Re: Access u-boot varibale from linux user space

Zhiming_Liu — Wed, 17 Dec 2025 03:09:16 GMT

Hi,

Please refer patch here.

https://github.com/nxp-imx-support/meta-swupdate-imx/blob/kirkstone_5.15.71_2.2.0/recipes-bsp/u-boot/files/0001-enable-env_redunand-bootcount-limit-LF_v5.15.71-2.2.0.patch

https://github.com/nxp-imx-support/meta-swupdate-imx/blob/kirkstone_5.15.71_2.2.0/recipes-bsp/u-boot/u-boot-imx_%25.bbappend

Best Regards,
Zhiming

Re: Access u-boot varibale from linux user space

kartheek — Thu, 18 Dec 2025 06:10:45 GMT

Hi,

After configuring fw_env.config in etc folder and running saveenv in U-Boot, I can access U-Boot environment variables from Linux user space.

However, we plan to remove the serial debugger later. In that case, we won’t be able to execute saveenv at the U-Boot prompt. Is there a way to automatically save the environment during the boot process?

Thanks,
Kartheek

Re: Access u-boot varibale from linux user space

Zhiming_Liu — Fri, 19 Dec 2025 00:29:40 GMT

Hi,

You can define a command in uboot env, then run it in mmcboot(include/configs/<board>.h).

Best Regards,
Zhiming

Re: Access u-boot varibale from linux user space

vopal — Mon, 22 Dec 2025 13:19:44 GMT

If you carefully read the u-boot documentation, you'll find that u-boot provides a complete solution. During u-boot compilation, `make u-boot-initial-env` generates default u-boot environment variables. `fw_printenv`/`fw_setenv` can use the `-f` parameter on the first run to access this default u-boot environment variable file. This is also the method used by swupate on its first run.

Re: Access u-boot varibale from linux user space

vopal — Mon, 22 Dec 2025 14:49:05 GMT

If I remember correctly, yocto generates a default environment variable file for u-boot by default.

Re: Access u-boot varibale from linux user space

vopal — Mon, 22 Dec 2025 15:07:44 GMT

@kartheek

This link is helpful.

https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/u-boot-environment-preset-for-sdcard-mirror/ta-p/1702549