Microdroid kernel

This directory contains prebuilt images of the Linux kernel that is used in Microdroid. The kernel is built from the same source tree as Generic Kernel Image (GKI), but with a different config where most of the config items are turned off to make the kernel fast & slim.

How to build the Microdroid kernels

Checkout the GKI source code.

repo init -u https://android.googlesource.com/kernel/manifest -b android14-5.15
repo sync

Build the Microdroid kernels manually

For ARM64

FAST_BUILD=1 BUILD_CONFIG=common-modules/virtual-device/build.config.microdroid.aarch64 build/build.sh

For x86_64,

FAST_BUILD=1 BUILD_CONFIG=common-modules/virtual-device/build.config.microdroid.x86_64 build/build.sh

Note that FAST_BUILD=1 is not mandatory, but will make your build much faster.

How to update Microdroid kernel prebuilts

For manually built kernels (only for your own development)

Copy the built kernel image to the Android source tree directly, and build the virt APEX.

For ARM64,

cp out/android14-5.15/dist/Image <android_checkout>/packages/modules/Virtualization/microdroid/kernel/arm64/kernel-5.15

For x86_64,

cp out/android14-5.15/dist/bzImage <android_checkout>/packages/modules/Virtualization/microdroid/kernel/arm64/kernel-5.15

For official updates

Use the download_from_ci script to automatically fetch the built images from a specific <build_id> and make commits with nice history in the message.

cd <android_checkout>/packages/modules/Virtualization
repo start <topic_name>
cd <kernel_checkout>
ANDROID_BUILD_TOP=<android_checkout> ./build/kernel/gki/download_from_ci  --update-microdroid -b <bug_id> <build_id>
cd <android_checkout>/packages/modules/Virtualization
repo upload .