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311bd47795
Fix the instructions in the README guide when setting up kernel source code. Fixes: #673 Signed-off-by: Nitesh Konkar <niteshkonkar@in.ibm.com>
131 lines
4.8 KiB
Markdown
131 lines
4.8 KiB
Markdown
# Build Kata Containers Kernel
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* [Requirements](#requirements)
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* [Setup kernel source code](#setup-kernel-source-code)
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* [Build the kernel](#build-the-kernel)
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* [Install the Kernel in the default path for Kata](#install-the-kernel-in-the-default-path-for-kata)
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* [Submit Kernel Changes](#submit-kernel-changes)
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* [How is it tested](#how-is-it-tested)
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* [Contribute](#contribute)
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This document explains the steps to build a kernel recommended for use with
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Kata Containers. To do this use `build-kernel.sh`, this script
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automates the process to build a kernel for Kata Containers.
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## Requirements
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The `build-kernel.sh` script requires an installed Golang version matching the
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[component build requirements](https://github.com/kata-containers/documentation/blob/master/Developer-Guide.md#requirements-to-build-individual-components).
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## Setup kernel source code
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```bash
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$ go get -d -u github.com/kata-containers/packaging
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$ cd $GOPATH/src/github.com/kata-containers/packaging/kernel
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$ ./build-kernel.sh setup
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```
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The script `./build-kernel.sh` tries to apply the patches from
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`${GOPATH}/src/github.com/kata-containers/packaging/kernel/patches/` when it
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sets up a kernel. If you want to add a source modification, add a patch on this
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directory.
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The script also adds a kernel config file from
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`${GOPATH}/src/github.com/kata-containers/packaging/kernel/configs/` to `.config`
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in the kernel source code. You can modify it as needed.
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## Build the kernel
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After the kernel source code is ready, it is possible to build the kernel.
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```bash
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$ ./build-kernel.sh build
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```
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## Install the Kernel in the default path for Kata
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Kata Containers uses some default path to search a kernel to boot. To install
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on this path, the following command will install it to the default Kata
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containers path (`/usr/share/kata-containers/`).
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```bash
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$ ./build-kernel.sh install
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```
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## Submit Kernel Changes
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Kata Containers packaging repository holds the kernel configs and patches. The
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config and patches can work for many versions, but we only test the
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kernel version defined in the [runtime versions file][runtime-versions-file].
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For further details, see [the kernel configuration documentation](configs).
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## How is it tested
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The Kata Containers CI scripts install the kernel from [CI cache
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job][cache-job] or build from sources.
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If the kernel defined in the [runtime versions file][runtime-versions-file] is
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built and cached with the latest kernel config and patches, it installs.
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Otherwise, the kernel is built from source.
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The Kata kernel version is a mix of the kernel version defined in the [runtime
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versions file][runtime-versions-file] and the file `kata_config_version`. This
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helps to identify if a kernel build has the latest recommend
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configuration.
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Example:
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```bash
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# From https://github.com/kata-containers/runtime/blob/master/versions.yaml
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$ kernel_version_in_versions_file=4.10.1
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# From https://github.com/kata-containers/packaging/blob/master/kernel/kata_config_version
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$ kata_config_version=25
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$ latest_kernel_version=${kernel_version_in_versions_file}-${kata_config_version}
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```
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The resulting version is 4.10.1-25, this helps identify whether or not the kernel
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configs are up-to-date on a CI version.
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## Contribute
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In order to do Kata Kernel changes. There are places to contribute:
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1. [Kata runtime versions file][runtime-versions-file]: This file points to the
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recommended to use by Kata. To update the kernel version send a pull request
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to update that version. The Kata CI will run all the use cases and verify it
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works.
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1. Kata packaging repository. This repository contains all the kernel configs
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and patches recommended for Kata Containers kernel:
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- If you want to upload one new configuration (new version or architecture
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specific) make sure the config file name has the following format:
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```bash
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# Format:
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$ ${arch}_kata_${hypervisor_target}_${major_kernel_version}.x
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# example:
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$ arch=x86_64
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$ hypervisor_target=kvm
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$ major_kernel_version=4.19
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# Resulting file
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$ name: x86_64_kata_kvm_4.19.x
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```
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- Kernel patches, the CI and packaging scripts will apply all patches in the
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[patches directory][patches-dir].
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Note: The kernel version and configuration file live in different locations,
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which could result in a circular dependency on your (runtime or packaging) PR.
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In this case, the PR you submit needs to be tested together with a patch from
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another Kata Containers repository. To do this you have to specify which
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repository and which pull request [it depends on][depends-on-docs].
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[runtime-versions-file]: https://github.com/kata-containers/runtime/blob/master/versions.yaml
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[patches-dir]: https://github.com/kata-containers/packaging/tree/master/kernel/patches
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[depends-on-docs]: https://github.com/kata-containers/tests/blob/master/README.md#breaking-compatibility
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[cache-job]: http://jenkins.katacontainers.io/job/image-nightly-x86_64/
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