Please help me on kernel configuration with rt-patch applied

Hello,

I'm facing a strange issue on kernel configuration with rt-patch applied.

I'm using buildroot-2020.02.8 with kernel 5.4.78 and rt-patch 5.4.78-rt44, patch is applied through BR2_GLOBAL_PATCH_DIR variable and custom kernel configuration that takes it into account is passed through BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE variable.

Patch is correctly applied and above configuration file is copied into kernel build directory. However after this the following message is displayed:

Using /home/user/buildroot-2020.02.8/output/build/linux-5.4.78/.config as base #

# merged configuration written to
/home/user/buildroot-2020.02.8/output/build/linux-5.4.78/.config
(needs make)
#
scripts/kconfig/conf  --olddefconfig Kconfig
#

And then my custom configuration is overwritten and rt-patch config variables are not present anymore in actual kernel .config file.

I also tried with BR2_LINUX_KERNEL_PATCH variable, but the result is the same.

May you please help me? I've used BR2_GLOBAL_PATCH_DIR variable to apply other kernel patches since now without any problems.

Thanks, Matteo

Hello Andreas,

many thanks for your answer and sorry for the delay of mine, during the weekend I did not have the chance to work on this issue.

Anyway, I checked BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES variable in my Buildroot configuration file and is empty, my approach
for kernel patching always worked in other cases, what am I doing wrong now?

Regards, Matteo

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-----Messaggio originale-----
Da: Andreas Ziegler [mailto:[email protected]]
Inviato: venerdì 22 ottobre 2021 18:27
A: Pampolini Matteo <[email protected]>
Oggetto: Re: Please help me on kernel configuration with rt-patch applied

Ciao Matteo,

Quoted 18 lines

Hello,

I'm facing a strange issue on kernel configuration with rt-patch applied.

I'm using buildroot-2020.02.8 with kernel 5.4.78 and rt-patch 5.4.78-rt44, patch is applied through BR2_GLOBAL_PATCH_DIR variable and custom kernel configuration that takes it into account is passed through BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE variable.

Patch is correctly applied and above configuration file is copied into kernel build directory. However after this the following message is displayed:

Quoted 8 lines

Using /home/user/buildroot-2020.02.8/output/build/linux-5.4.78/.config as base
#

# merged configuration written to
/home/user/buildroot-2020.02.8/output/build/linux-5.4.78/.config
(needs make)
#
scripts/kconfig/conf  --olddefconfig Kconfig #

It looks as if you have a configuration fragment file configured which is big enough to overwrite everything. Check BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES directly below the kernel configuration file and the content of the file.

Quoted 5 lines

And then my custom configuration is overwritten and rt-patch config variables are not present anymore in actual kernel .config file.

I also tried with BR2_LINUX_KERNEL_PATCH variable, but the result is the same.

I do not think this is patch related; you still should be able to configure RT settings when you execute 'make nconfig'.

Quoted 2 lines

May you please help me? I've used BR2_GLOBAL_PATCH_DIR variable to apply other kernel patches since now without any problems.

Kind regards,
Andreas

Quoted 1 line

Thanks, Matteo