meta-linux-mainline

A collection of Yocto Project recipes for the mainline and stable Linux kernel releases from kernel.org.

• Goals and non-goals of this layer
  • Goals: things this layer is intentionally aiming to achieve
  • Non-goals: things this layer is intentionally aiming not to achieve
• Contents of this layer
• Using this layer
  • As a dependency of a BSP layer
  • Replacing your vendor kernel
• Contributing to this layer
• Maintainers
• License

Goals and non-goals of this layer

Goals: things this layer is intentionally aiming to achieve

• We provide recipes for all Linux kernel releases currently supported on kernel.org. These recipes are regularly updated to make it easy to follow mainline releases, the latest stable series or a chosen LTS release series.

• We aim to be compatible with all currently supported Yocto Project releases as well as the upstream master branch.

• We provide examples of how to use this layer in the form of BSP configurations for various QEMU and Raspberry Pi targets.

Non-goals: things this layer is intentionally aiming not to achieve

• We do not carry patches against upstream kernel releases without a documented, exceptionally good reason.

• We do not support obsolete kernel versions. Recipes are only provided for the latest patch release within a given release series. Once a release series becomes End-Of-Life (EOL) on kernel.org, the corresponding recipe will be removed from this layer.

• We provide no guarantees that kernels built with this layer will boot successfully on your hardware or that particular features (e.g. perf) will work out of the box. The example BSP configurations are not intended to be directly used in production. To use this layer in production, create your own layer for configuration & integration and use this layer as a dependency.

• We do not aim to replace the linux-yocto kernel from the Yocto Project.

Contents of this layer

This layer currently contains the following kernel recipes:

• linux-stable (multiple versions): These recipes follow the patch releases in each currently supported stable release series of the Linux kernel. The currently supported release series can be seen at kernel.org.

• linux-mainline: This recipe uses AUTOREV to pull the latest commit to the master branch of the mainline Linux repository. As this branch includes release candidate (rc) kernels it is only recommended for testing and active development.

Using this layer

As a dependency of a BSP layer

It is expected that some BSP layers will directly use this layer to provide a vanilla kernel recipe where a vendor kernel is not needed. In these cases no changes will be needed to make use of the kernel recipes in this layer.

For other BSP layers you may be given a choice between a vendor kernel and a vanilla kernel. The method of choosing the desired kernel provider will be BSP-specific. An example of this can be seen in the meta-sancloud BSP where the kernel recipes from this layer are used if BBE_KERNEL_PROVIDER is set to stable, lts or mainline.

Replacing your vendor kernel

Many Board Support Package (BSP) layers default to using a vendor-specific kernel repository (containing many patches which haven't been incorporated into the upstream kernel) or an obsolete kernel version. However, most boards are supported by the mainline Linux kernel to some degree or other. Switching to a mainline kernel allows you to take advantage of bugfixes & new features and enables you to work more closely with the kernel community.

Selecting a kernel recipe

The kernel recipes in this layer are intended as optional replacements for the vendor kernel recipes included in a BSP directory. Simply including this layer in your build will not alter the kernel recipe in use. To select a kernel recipe from this layer you should override the PREFERRED_PROVIDER_virtual/kernel variable to either linux-stable or linux-mainline as appropriate. If using linux-stable it also also possible to set PREFERRED_VERSION_linux-stable to choose a stable kernel release series.

To simplify the process of selecting a kernel recipe from this layer, 3 .inc files are provided which can be included from your local.conf file or from a distro conf file:

• conf/linux-mainline/stable.inc: Selects the linux-stable recipe for the latest stable kernel version (typically not an LTS kernel).

• conf/linux-mainline/lts.inc: Selects the linux-stable recipe for the latest LTS kernel version.

• conf/linux-mainline/mainline.inc: Selects the linux-mainline recipe.

Board support

To support a particular target board with linux-stable or linux-mainline it is usually necessary to select an appropriate defconfig from the kernel source tree. It may also be necessary to provide additional configuration or to make changes to the bootloader to properly support a vanilla kernel.

This layer includes a selection of .inc files which add support for a vanilla kernel if it is not supported already by the relevant BSP layer. To use the appropriate .inc file, add the following line to your local.conf or distro conf file:

include conf/linux-mainline/bsp/${MACHINE}

Contributing to this layer

meta-linux-mainline is developed on sourcehut at https://sr.ht/~pbarker/meta-linux-mainline/.

If you find any bugs or have a feature request feel free to open a ticket in the issue tracker.

We welcome contributions to this layer, provided that they fit within the goals and non-goals of this layer identified above. Each commit or patch must include a Signed-off-by line indicating acceptance of the Developer's Certificate of Origin for it to be accepted into this layer.

Please send patches and pull requests for this project to the maintainer's public inbox with [meta-linux-mainline] in the subject line. Please use plain text email when sending messages to this list. Submitted patches and other discussions may be found in the archives of this mailing list.

The following commands can be used to configure git to format patches appropriately:

git config format.to '~pbarker/[email protected]'
git config format.subjectPrefix 'meta-linux-mainline][PATCH'

Further instructions on how to set up git to send emails can be found at git-send-email.io.

Maintainers

Paul Barker <[email protected]>

License

The files in this repository are distributed under various licenses depending on the type of content:

• Recipes, config files and scripts in this layer are distributed under the MIT License for compatibility with other Yocto Project layers, with the exception of auto-generated files.

• Documentation files (such as this readme) are distributed under the Creative Commons Attribution 4.0 International License.

• Metadata files, trivial configuration files and auto-generated files (such as the MAINTAINERS list, .gitignore and linux-mainline.bb) are distributed under the CC0 1.0 Public Domain Dedication.