Build KIS Image (Kernel, Initrd, System)

Abstract

This page explains how to build an image that consists of three components: the kernel, an initrd, and an optional root filesystem image. In KIWI NG terminology, this type of image is called KIS.

A KIS image is a collection of image components that are not associated with a dedicated use case. This means that as far as KIWI NG is concerned, it is not known in which environment these components are expected to be used. The predecessor of this image type was called pxe under the assumption that the components will be used in a PXE boot environment. However, this assumption is not always true, and the image components may be used in different ways. Because there are so many possible deployment strategies for a kernel plus initrd and an optional system root filesystem, KIWI NG provides this as the universal KIS type.

The former pxe image type still exists, but it is expected to be used only in combination with the legacy netboot infrastructure, as described in Build PXE Root Filesystem Image for the legacy netboot infrastructure.

To add a KIS build to an appliance, create a type element with image set to kis in config.xml, as shown below:

<preferences>
    <type image="kis"/>
</preferences>

With this image type setup, KIWI NG builds a kernel and initrd not associated with any system root filesystem. Normally, such an image is only useful with certain custom dracut extensions as part of the image description.

The following attributes of the type element are often used when building KIS images:

• filesystem: Specifies the root filesystem and triggers the build of an additional filesystem image of that filesystem. The generated kernel command-line options file (append file) will then also include a root= parameter that references this filesystem image’s UUID. Whether the information from the append file should be used or not is optional.

• kernelcmdline: Specifies kernel command-line options that are part of the generated kernel command-line options file (append file). By default, the append file contains neither information nor a reference to the root UUID if the filesystem attribute is used.

All other attributes of the type element that apply to an optional root filesystem image remain in effect in the system image of a KIS image as well.

With the appropriate settings present in config.xml, you can use KIWI NG to build the image:

$ sudo kiwi-ng --type kis system build \
    --description kiwi/build-tests/x86/tumbleweed/test-image-pxe \
    --set-repo https://download.opensuse.org/tumbleweed/repo/oss \
    --target-dir /tmp/myimage

The resulting image components are saved in /tmp/myimage. Outside of a deployment infrastructure, the example KIS image can be tested with QEMU as follows:

$ sudo qemu
    -kernel /tmp/myimage/*.kernel \
    -initrd /tmp/myimage/*.initrd \
    -append "$(cat /tmp/myimage/*.append) rw" \
    -drive file=/tmp/myimage/kiwi-test-image-pxe.*-1.15.6,if=virtio,driver=raw \
    -serial stdio

Note

Testing the components of a KIS image normally requires a deployment infrastructure and a deployment process. An example of a deployment infrastructure using PXE is provided by KIWI NG with the netboot infrastructure. However, that netboot infrastructure is no longer developed and is only kept for compatibility reasons. For details, see Build PXE Root Filesystem Image for the legacy netboot infrastructure.