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Revamp kernel config section
Revamp kernel configuration section to not force the workflow of the CL team.
This commit is contained in:
puneetse
@@ -19,8 +19,8 @@ used for development instead. The latest source RPM files are available at:
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`https://download.clearlinux.org/current/source/SRPMS/`_
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Request the change be included with the |CL| kernel
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***************************************************
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Request changes be included with the |CL| kernel
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************************************************
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If the kernel modification you need is already open source and likely to be
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useful to others, consider submitting a request to include it in the
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@@ -47,7 +47,6 @@ To create a custom kernel, start with the |CL| development environment.
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Then make changes to the kernel, build it, and install it.
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Install the |CL| development tooling framework
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==============================================
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@@ -129,84 +128,106 @@ by autospec are not available and changes must be made manually.
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%define ktarget native
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.. note::
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Consider changing the Name from *linux* in the RPM spec file to easily
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identify a modified kernel.
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- Consider changing the Name from *linux* in the RPM spec file to easily
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identify a modified kernel.
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Consider changing the ktarget from *native* in the RPM spec file to easily
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identify a modified kernel.
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- Consider changing the ktarget from *native* in the RPM spec file to easily
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identify a modified kernel.
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#. Commit and save the changes to the file.
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Pull a copy of the kernel source code
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=====================================
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You will need to obtain a local copy of the source code to make modifications
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against.
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#. Run make sources to pull the kernel source code specified in the RPM
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SPEC file. In the example, it downloads the
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:file:`linux-4.20.8.tar.xz` file.
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.. code-block:: bash
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make sources
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#. Extract the kernel source code archive. This will create a working copy of
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the Linux source which you can modify.
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.. code-block:: bash
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tar -xvf linux-4.20.8.tar.xz
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#. Navigate to the extracted directory. In this example, it has been
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extracted into a :file:`linux-4.20.8` directory.
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.. code-block:: bash
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cd linux-4.20.8/
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Modify kernel configuration
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===========================
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Existing kernel features and in-tree kernel modules can be enabled or
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disabled in the kernel configuration file, :file:`.config` , at compile time.
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The kernel source has many different configuration options available to pick
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support different hardware and software features.
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To manage unique changes that have been made to the kernel config file,
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|CL| uses a kernel config fragment file named :file:`config-fragment`.
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Managing kernel configuration changes with a configuration fragment file
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instead of directly editing the :file:`.config` file helps identify the
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unique configuration changes that have been made and makes applying any
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future default configuration values easier.
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The :file:`config-fragment` is the **only** file that is modified and is
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eventually merged with the main :file:`.config`.
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These configuration values must be provided in the :file:`.config` file at
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compile time.
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#. Make sure you have followed the steps to
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`Pull a copy of the kernel source code`_ and are in the kernel source
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working directory.
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#. Open the kernel :file:`config-fragment` file in an editor.
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#. If you have an existing :file:`.config` file from an old kernel, copy it
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into the working directory as :file:`.config` for comparison.
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Otherwise, generate a base kernel configuration with default values
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for the linux source version and put them in a :file:`.config` file
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within the working directory.
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.. code-block:: bash
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$EDITOR config-fragment
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make defconfig
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#. Find the configuration values you are looking for.
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If a particular setting does not already exist, it can be added manually.
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#. Make any desired changes to the :file:`.config` using a kernel
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configuration tool. Below are some popular options:
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For example, the snippet below shows BTRFS support configuration indicating
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it is enabled in-tree.
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- :command:`$EDITOR .config` - the .config file can be directly edited for
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simple changes with names that are already known.
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- :command:`make config` - a text-based tool that asks questions
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one-by-one to decide configuration options.
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- :command:`make menuconfig` - a terminal user interface that provides
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menus to decide configuration options.
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- :command:`make xconfig` - a graphical user interface that provides
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tree views to decide configuration options.
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More configuration tools can be found by looking at the make help:
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:command:`make help | grep config`
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#. Commit and save the changes to the :file:`.config` file.
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#. Copy the :file:`.config` file from the kernel source directory into
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the kernel package directory as :file:`config` for inclusion in the build.
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.. code-block:: bash
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CONFIG_BTRFS_FS=y
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CONFIG_BTRFS_FS_POSIX_ACL=y
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cp .config ../config
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#. Modify the configuration values as desired.
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For example, the snippet below shows BTRFS support configuration changed
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change to be disabled and commented out.
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.. code-block:: bash
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# CONFIG_BTRFS_FS is not set
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# CONFIG_BTRFS_FS_POSIX_ACL is not set
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#. Commit and save the changes to the :file:`config-fragment` file.
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#. Run the :command:`make config` command to apply the changes made in the
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:file:`config-fragment` file and regenerate the :file:`config` file.
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.. code-block:: bash
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make config
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.. note::
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The |CL| packaging tools make use of :command:`mock` environments for
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building software.
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If you want to make use of GUI tools to edit the kernel confguration, such as
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:command:`menuconfig`, instead of manually editing the :file:`config`
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file, you can from the :command:`mock` environment under
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:file:`/var/lib/mock/clear-linux/root/builddir/build/BUILD/kernel-*`
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Modify kernel source code
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=========================
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@@ -223,25 +244,9 @@ consider using a patch management tool in addition to Git such as
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`Quilt`_.
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#. Run make sources to pull the kernel source code specified in the RPM
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SPEC file. In the example, it downloads the
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:file:`linux-4.20.8.tar.xz` file.
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.. code-block:: bash
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make sources
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#. Extract the kernel source code archive and enter the extracted directory.
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This will create a working copy of the Linux source you can modify.
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In this example, it is extracted into a
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:file:`linux-4.20.8` directory.
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.. code-block:: bash
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tar -xvf linux-4.20.8.tar.xz
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cd linux-4.20.8/
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#. Make sure you have followed the steps to
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`Pull a copy of the kernel source code`_ and are in the kernel source
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working directory.
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#. Make any desired code changes to the Linux source code files.
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@@ -349,10 +354,12 @@ are persistent and distributed with a customized kernel.
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$EDITOR cmdline
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#. Make any desired change to the kernel parameters.
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For example, you can remove the :command:`quiet` parameter to see more
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verbose output of kernel log messages during the boot process.
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#. Commit and save the changes to the :file:`cmdline` file.
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See the
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@@ -393,12 +400,14 @@ machine for testing. This approach works well for individual development or
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testing. For a more scalable and customizable approach, consider using the
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`mixer tool`_ to provide a custom kernel with updates.
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1. Install the kernel onto the local system by extracting the RPM with the :command:`rpm2cpio` command.
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1. Install the kernel onto the local system by extracting the RPM with the
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:command:`rpm2cpio` command.
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.. code-block:: bash
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sudo rpm2cpio linux%{name}-%{version}-%{release}.x86_64.rpm | (cd /; sudo cpio -i -d -u -v);
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#. Update the |CL| boot manager using :command:`clr-boot-manager` and reboot.
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.. code-block:: bash
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@@ -408,6 +417,7 @@ testing. For a more scalable and customizable approach, consider using the
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sudo reboot
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#. After a reboot, verify the customized kernel is running.
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.. code-block:: bash
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