How to customize kernel configuration with OpenSTLinux and Yocto?

[AJank.2]

Following the tutorial on How to customize the Linux kernel I made steps as below:

1. Create a custom layer.
2. Add it to the build configuration in bblayers.conf.
3. Create a fragment.config with bitbake menuconfig and put it into my-layer/recipes-kernel/linux/linux-stm32mp/5.15/ as the kernel version is 5.15.
4. Create a my-layer/recipes-kernel/linux/linux-stm32mp_%.bbappend file as advised in the tutorial:

FILESEXTRAPATHS:prepend := "${THISDIR}:${THISDIR}/${PN}:"
 
KERNEL_CONFIG_FRAGMENTS:append = "${WORKDIR}/fragments/${LINUX_VERSION}/fragment-custom.config"
SRC_URI:append = " file://${LINUX_VERSION}/fragment-custom.config;subdir=fragments "

It seems that the kernel configuration wasn't applied at all, is there something that I'm doing wrong?

Without the FILEXTRAPATHS line, the file couldn't be found, yocto didn't look into my-layer at all.

[Erwan SZYMANSKI]

Hello @Antoni Jankowski​ ,

That is strange that you need this FILESEXTRAPATHS.

Did you already check if your layer was well parsed by Yocto with doing the following command ?

PC $> bitbake-layers show-layers

Kind regards,

Erwan.

[AJank.2]

Yes, the layer is visible and actually the first on the list of bitbake-layers show-layers. When trying without the FILESEXTRAPATHS below warning is displayed, which later turns into an error:

WARNING: /layers/meta-st/meta-st-stm32mp/recipes-kernel/linux/linux-stm32mp_5.15.bb: Unable to get checksum for linux-stm32mp SRC_URI entry fragment-custom.config: file could not be found

[Erwan SZYMANSKI]

@Antoni Jankowski​ ,

Is it possible for you to give me a tarball containing your my-layer ? I would like to reproduce from my side to understand the issue.

Kind regards,

Erwan.

[AJank.2]

Sure, checkout my-layer.tar in the attachment. To replicate the issue, check the kernel config options set in my-layer/recipes-kernel/linux/linux-stm32mp/5.15/fragment-custom.config and then when the image is build and running check /proc/config.gz and compare them. In my case the options set in the fragment-custom.config are missing from the final running config.

Kind regards,

Antoni

[Erwan SZYMANSKI]

Hello @Antoni Jankowski​ ,

Thanx for sharing, I will reproduce from my side.

Just to be sure to not face a typo issue, can you modify the name of your layer with adding "meta-" at the beginning ?

I think Yocto needs it in major situations, but I do not know in details how it can react if it does not find this prefix on a layer.

Kind regards,

erwan.

[AJank.2]

I think this is just the naming convention. I had to script the layer down out of all the proprietary names before sharing it with you. Anyway, I did my own fixing in the meantime, it could be so that the layer priority was at fault, as it was set to be the same as the original meta-st layers - at 6. Perhaps that through Yocto off the track. Let me know if you find something and I'll keep looking for errors as well.

[AJank.2]

I think this is just the naming convention. I had to script the layer down out of all the proprietary names before sharing it with you. Anyway, I did my own fixing in the meantime, it could be so that the layer priority was at fault, as it was set to be the same as the original meta-st layers - at 6. Perhaps that through Yocto off the track. Let me know if you find something and I'll keep looking for errors as well.

[Erwan SZYMANSKI]

Interesting, so when you change the priority of "my-layer" to align it with the one of layer containing ST kernel, you do not have trouble anymore ?

Rgs,

Erwan.

[AJank.2]

I'm still waiting for the build to finish, will let you know once tested, hopefully in about an hour.