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feat: Kernel config validation tool (#16224)
Adds a Python-based kernel config checker that validates kernel .config files against a centralized JSON schema of required configurations. This catches unintentional config regressions during PR review.
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‎.github/workflows/check-kernel-configs.yml‎

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# Copyright (c) Microsoft Corporation.
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# Licensed under the MIT License.
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# This action checks that required kernel configs have not been removed or
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# modified to an undesirable value.
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name: Kernel Required Configs Check
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on:
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push:
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branches: [3.0*, fasttrack/*]
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paths:
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- 'SPECS/kernel*/config*'
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pull_request:
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branches: [3.0*, fasttrack/*]
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paths:
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- 'SPECS/kernel*/config*'
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jobs:
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check:
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name: Kernel configs check
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runs-on: ubuntu-latest
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steps:
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# Checkout the branch of our repo that triggered this action
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- name: Workflow trigger checkout
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uses: actions/checkout@v4
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- name: Get base commit for PRs
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if: ${{ github.event_name == 'pull_request' }}
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run: |
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git fetch origin ${{ github.base_ref }}
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echo "base_sha=$(git rev-parse origin/${{ github.base_ref }})" >> $GITHUB_ENV
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echo "Merging ${{ github.sha }} into ${{ github.base_ref }}"
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- name: Get base commit for Pushes
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if: ${{ github.event_name == 'push' }}
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run: |
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git fetch origin ${{ github.event.before }}
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echo "base_sha=${{ github.event.before }}" >> $GITHUB_ENV
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echo "Merging ${{ github.sha }} into ${{ github.event.before }}"
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# For consistency, we use the same major/minor version of Python that Azure Linux ships
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- name: Setup Python 3.12
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uses: actions/setup-python@v5
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with:
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python-version: 3.12
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- name: Get Python dependencies
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run: python3 -m pip install -r toolkit/scripts/requirements.txt
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# Check if kernel configs changed
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- name: Check if config files changed
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run: |
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echo "Files changed: '$(git diff-tree --no-commit-id --name-only -r ${{ env.base_sha }} ${{ github.sha }})'"
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changed_configs=$(git diff-tree --diff-filter=d --no-commit-id --name-only -r ${{ env.base_sha }} ${{ github.sha }} | { grep "SPECS/kernel.*/config.*$" || test $? = 1; })
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echo "Files to validate: '${changed_configs}'"
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echo "updated_configs<<EOF" >> $GITHUB_ENV
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echo "${changed_configs}" >> $GITHUB_ENV
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echo "EOF" >> $GITHUB_ENV
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# Run kernel config checker against each changed config file
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- name: Run kernel config checking script
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if: ${{ env.updated_configs != '' }}
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run: |
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JSON_PATH="toolkit/scripts/kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json"
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# Extract kernel names that have overrides in the JSON (these are the kernels we track)
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tracked_kernels=$(python3 -c "
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import json
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with open('${JSON_PATH}') as f:
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data = json.load(f)
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for o in data['overrides']:
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print(o['name'])
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")
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echo "Tracked kernels: ${tracked_kernels}"
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failed=0
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holder="${{ env.updated_configs }}"
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for file in $holder; do
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# Extract kernel name from path (e.g., SPECS/kernel-hwe/config -> kernel-hwe)
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kernel_name=$(echo "$file" | sed 's|SPECS/\([^/]*\)/.*|\1|')
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# Skip kernels that don't have overrides in the JSON
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if ! echo "${tracked_kernels}" | grep -qx "${kernel_name}"; then
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echo "============================================"
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echo "Skipping: ${file} (kernel=${kernel_name} not tracked in JSON)"
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echo "============================================"
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continue
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fi
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# Determine architecture from filename
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if [[ "$file" == *"aarch64"* ]]; then
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arch="arm64"
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else
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arch="x86_64"
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fi
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echo "============================================"
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echo "Checking: ${file} (kernel=${kernel_name}, arch=${arch})"
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echo "============================================"
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if ! (cd toolkit/scripts && python3 -m kernel_config_checker.check_config \
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"../../${file}" \
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kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json \
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"${kernel_name}" "${arch}"); then
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failed=1
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fi
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done
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if [ "$failed" -eq 1 ]; then
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echo ""
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echo "✗ One or more kernel config checks failed"
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exit 1
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fi

‎toolkit/scripts/kernel_config_checker/README.md‎

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# Kernel Config Checker
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A robust kernel configuration validation system using Pydantic v2 schemas. Supports default configurations and per-kernel overrides with architecture-specific settings.
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## Features
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- **Schema-based validation** - Uses Pydantic v2 for robust config validation
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- **Multi-architecture support** - Handles x86_64 and arm64 architectures
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- **Flexible overrides** - Default configs with per-kernel overrides
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- **Interactive config management** - Add new configs with guided prompts
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- **Config querying** - Check config values across all kernels/architectures
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- **Legacy conversion** - Tools to migrate existing configurations
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## Installation
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From the repo root, install the Python dependencies:
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```bash
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pip install -r toolkit/scripts/requirements.txt
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```
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All commands below should be run from `toolkit/scripts/`:
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```bash
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cd toolkit/scripts
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```
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## Usage
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### Check Kernel Config
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Validate a `.config` file against intentional configurations:
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```bash
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python -m kernel_config_checker.check_config /path/to/.config kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json kernel-name architecture
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```
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Example:
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```bash
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python -m kernel_config_checker.check_config kernel.config kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json kernel x86_64
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```
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### Add New Config
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Interactively add a new kernel configuration:
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```bash
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python -m kernel_config_checker.check_config --add-config kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json
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```
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Features:
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- Add to default or override sections
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- Support for single or multiple architectures
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- Leave architectures blank to omit them from JSON
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- Create new override sections or use existing ones
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### Query Config Values
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Check a config value across all architectures and kernels:
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```bash
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python -m kernel_config_checker.check_config --check-all kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json CONFIG_NAME
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```
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Example:
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```bash
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python -m kernel_config_checker.check_config --check-all kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json CONFIG_DRM
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```
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## Configuration Schema
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The system uses a structured JSON schema with default and override sections:
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```json
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{
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"default": {
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"kernel_configs": [
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{
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"name": "CONFIG_EXAMPLE",
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"values": [
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{
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"architecture": "x86_64",
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"value": "y"
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},
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{
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"architecture": "arm64",
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"value": "m"
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}
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],
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"justification": "Explanation for this config"
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}
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]
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},
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"overrides": [
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{
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"name": "kernel-64k",
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"kernel_configs": [
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{
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"name": "CONFIG_ARM64_64K_PAGES",
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"values": [
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{
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"architecture": "arm64",
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"value": "y"
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}
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],
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"justification": "needed for 64k page size"
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}
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]
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}
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]
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}
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```
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### Architecture Support
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- Configs can specify values for `x86_64`, `arm64`, or both
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- When adding configs, leaving an architecture blank omits it from the JSON
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- At least one architecture must be specified
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### Value Types
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- `y` - Built into kernel
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- `m` - Built as module
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- `n` - Disabled ("is not set" or missing)
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- Custom values supported for specific configs
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## Project Structure
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```text
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toolkit/scripts/kernel_config_checker/
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├── schema/
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│ ├── __init__.py # Package init
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│ ├── schema.py # Pydantic schema definitions
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│ └── print_schema.py # Schema utility
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├── kernel_configs_json/
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│ └── azl3-os-required-kernel-configs.json # Main config file
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├── __init__.py # Package init
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├── check_config.py # Main checker and utilities
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└── README.md # This file
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```
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## Examples
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### Adding a Config for Single Architecture
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```bash
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$ python -m kernel_config_checker.check_config --add-config test.json
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Adding new kernel configuration...
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Enter config name (e.g., CONFIG_EXAMPLE): CONFIG_X86_ONLY
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Enter values for each architecture (y/n/m or specific value, leave blank to skip):
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x86_64 value: y
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arm64 value:
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Enter justification: Only needed on x86_64
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Add to [d]efault or [o]verride? [d]: d
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✓ Added CONFIG_X86_ONLY to default section
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```
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Results in:
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```json
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{
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"name": "CONFIG_X86_ONLY",
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"values": [
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{
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"architecture": "x86_64",
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"value": "y"
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}
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],
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"justification": "Only needed on x86_64"
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}
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```
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### Querying Config Values
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```bash
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$ python -m kernel_config_checker.check_config --check-all kernel_config_checker/kernel_configs_json/azl3-os-required-kernel-configs.json CONFIG_DRM
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Config: CONFIG_DRM
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arm64: default=m, kernel-hwe=y
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x86_64: default=m
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⚠️ Conflicts in: arm64
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Reason: amdgpu - https://github.com/microsoft/azurelinux/pull/10612
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```
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## Contributing
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1. Ensure all configs have proper justifications
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2. Test schema validation after changes
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3. Use the add-config command for consistency
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4. Validate configs against actual kernel .config files
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## License
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This project follows the same licensing as the Azure Linux project.

‎toolkit/scripts/kernel_config_checker/__init__.py‎

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# Copyright (c) Microsoft Corporation.
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# Licensed under the MIT License.

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