u-boot 2025.04 setting CONFIG_SYS_DEVICE_NULLDEV - where and how! Yocto 6.12.20

[edwardtyrrell]

Hi All,

We're having great difficulty in setting a few of the u-boot build configuration parameters in particular CONFIG_SYS_DEVICE_NULLDEV=y which needs to be off i.e. # CONFIG_SYS_DEVICE_NULLDEV is not set    

BTW The build is Yocto 6.12.20 and apparently there is an issue in not being able to use bitbake u-boot-imx -c menuconfig; which we can't. After fixing the KCONFIG_CONFIG_ENABLE_MENUCONFIG error the pop-up menuconfig window still fails. 

My actual question is where can I set CONFIG_SYS_DEVICE_NULLDEV (without using the GUI menuconfig as above)? I have tried a number of config files within tmp/work/imx7dsabresd-poky-linux-gnueabi/u-boot-imx but after compiling and deploying all the contents within the config files get overwritten.  Where is the source for these CONFIG settings? I've grep'd the entire build but cannot find a reliable file to change so the 'changes' are passed on to the autogenerated configs. 

 A number of the config files state "Automatically generated file; DO NOT EDIT." what and where are these files being generated?

Kind regards.

[AldoG]

Hello,

Could you share for which device are you trying to enable this Config?
Also, are you looking for only building Uboot?

Best regards/Saludos,
Aldo.

[edwardtyrrell]

Hi @AldoG 

It's the imx7dsabresd.

Thanks.

[AldoG · Accepted solution]

Hello,

Then for this target you'll need to modify the following defconfig:
https://github.com/nxp-imx/uboot-imx/blob/lf_v2025.04/configs/mx7dsabresd_defconfig

Secondly for configuring yocto for an specific target that you'll be using then you'll need to create a patch and then create a layer which will then apply the patch to the source, this would be the clean way to do it, at least for me.

But as it is yocto there is many ways to do it you may want to have a look here:
https://stackoverflow.com/questions/47047209/how-to-change-the-config-of-u-boot-in-yocto

Best regards/Saludos,
Aldo.

[edwardtyrrell]

Hi @AldoG 

Good reply, I've tried some of that already but have now decided to use the imx7s uboot for our debugging - its a simple serial output.

Kind regards.