79 lines
2.4 KiB
Markdown
79 lines
2.4 KiB
Markdown
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# Microdroid kernel
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This directory contains prebuilt images of the Linux kernel that is used in
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Microdroid. The kernel is built from the same source tree as Generic Kernel
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Image (GKI), but with a different config where most of the config items are
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turned off to make the kernel fast & slim.
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## How to build the Microdroid kernels
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### Checkout the GKI source code.
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```bash
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repo init -u https://android.googlesource.com/kernel/manifest -b common-android14-6.1
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repo sync
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```
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### Build the Microdroid kernels manually
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For ARM64
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```bash
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tools/bazel clean
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tools/bazel run --config=fast --lto=thin //common-modules/virtual-device:microdroid_aarch64_dist -- --dist_dir=out/dist
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```
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For x86\_64,
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```bash
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tools/bazel clean
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tools/bazel run --config=fast --lto=thin //common-modules/virtual-device:microdroid_x86_64_dist -- --dist_dir=out/dist
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```
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Note that
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[`--config=fast`](https://android.googlesource.com/kernel/build/+/refs/heads/master/kleaf/docs/fast.md)
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is not mandatory, but will make your build much faster.
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The build may fail in case you are doing an incremental build and the config has changed (b/257288175). Until that issue
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is fixed, do the clean build by invoking `tools/bazel clean` before the build command.
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### Change the kernel configs
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For ARM64
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```bash
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tools/bazel run //common-modules/virtual-device:microdroid_aarch64_config -- menuconfig
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```
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For x86\_64
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```bash
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tools/bazel run //common-modules/virtual-device:microdroid_x86_64_config -- menuconfig
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```
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## How to update Microdroid kernel prebuilts
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### For manually built kernels (only for your own development)
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Copy the built kernel image to the Android source tree directly, and build the virt APEX.
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For ARM64,
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```bash
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cp out/dist/Image <android_checkout>/packages/modules/Virtualization/microdroid/kernel/arm64/kernel-6.1
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```
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For x86\_64,
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```bash
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cp out/dist/bzImage <android_checkout>/packages/modules/Virtualization/microdroid/kernel/x86_64/kernel-6.1
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```
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### For official updates
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Use the `download_from_ci` script to automatically fetch the built images from
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a specific `<build_id>` and make commits with nice history in the message.
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```bash
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cd <android_checkout>/packages/modules/Virtualization
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repo start <topic_name>
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cd <kernel_checkout>
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ANDROID_BUILD_TOP=<android_checkout> ./build/kernel/gki/download_from_ci --update-microdroid -b <bug_id> <build_id>
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cd <android_checkout>/packages/modules/Virtualization
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repo upload .
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```
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