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I am trying to build a GKI kernel image from aosp. After updating the kernel config, the build does not seem to use my config. Instead, it always uses some default config.

How can I build with custom kernel configs?

I am using this branch: https://android.googlesource.com/kernel/devices/google/felix/+/refs/heads/android-gs-felix-6.1-android15-qpr2-beta

I am updating the config as follows:

CC=clang ARCH=arm64 LLVM=1 make gki_defconfig

CC=clang ARCH=arm64 LLVM=1 make nconfig #this is where I edit

CC=clang ARCH=arm64 LLVM=1 make savedefconfig

mv defconfig arch/arm64/configs/gki_defconfig

make mrproper

Then I build

ENABLE_STRICT_KMI=0 BUILD_AOSP_KERNEL=1 ./build_felix.sh --kernel_package=@//aosp

But on inspecting the kernel inside the boot.img using extract-ikconfig, I find that my config changes are not present. It seem to be reset.

This workflow used to work in older aosp branches but doesn't in newer ones. I also tried using bazel but in vain

tools/bazel run //common:kernel_aarch64_config -- nconfig

How can I build with custom kernel configs?

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  • Why are you assuming that the kernel build is going to use arch/arm64/configs/gki_defconfig? How have you tried to confirm if your assumption is true? BTW "I am updating the config as follows: ..." - This should actually be preceded with a make distclean or make mrproper. "Then I build ..." - Instead of sitting back and waiting for the build to complete, review the output on the screen to see what is actually performed. Commented Feb 6 at 1:44
  • @sawdust The older aosp branches used aosp/arch/arm64/configs/gki_defconfig and it looks like this does the same. I confirmed by removing/renaming the file (or adding a bad config) and it complains. I am running make mrproper but forgot to mention it in the question. The output unfortunately does not clearly indicate where the config is coming from. Commented Feb 6 at 3:05
  • "I confirmed by removing/renaming the file ... and it complains" - Okay, did you then locate the source code and investigate what this "it" does? Is there a make command to build the kernel, or is there something else? Commented Feb 6 at 6:23
  • Check that your new defconfig (after make savedefconfig) differs. Use scripts/diffconfig. I suspect that your changes somehow not applicable to the machine in question. Most likely due to some kernel configuration dependencies or limitations. Commented Feb 8 at 15:22
  • It looks like the "--use_prebuilt_gki=false" doesn't work as expected because device.bazelrc explicitly sets the option to download pre-built GKI. Disabling this option in the script was the only way I could get it to work. However, I guess more patching is required because after changing certain configs from 'm' to 'y', the build fails. For example, ERROR: Unable to find drivers/usb/class/cdc-acm.ko in any of the following directories: bazel-out/k8-fastbuild/bin/aosp/kernel_aarch64/staging/lib/modules/6.1.99-android14-11-gc151586fe278-dirty/kernel Commented Feb 9 at 20:27

1 Answer 1

Reset to default
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BUILD_AOSP_KERNEL=1 is deprecated and only adding --kernel_package=@//aosp seems not to work for me as well. But I found this in one of the other kernel build scripts and this seems to work:

--config=no_download_gki

E.g.,

./build_DEVICE.sh --kernel_package=@//aosp --config=no_download_gki

Clean builds will also not download any prebuilts anymore.

https://android.googlesource.com/kernel/devices/google/akita/+/a67ed82dbf3baabcf9d5e256284961f4aa1949f7%5E%21/#F0

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