Environment variables exported for plugins¶

If --verbose is used, $KERNEL_INSTALL_VERBOSE=1 will be exported for plugins. They may output additional logs in this case.

$KERNEL_INSTALL_MACHINE_ID is set for the plugins to the desired machine-id to use. It's always a 128-bit ID. Normally it's read from /etc/machine-id, but it can also be overridden via $MACHINE_ID (see below). If not specified via these methods a fallback value will generated by kernel-install, and used only for a single invocation.

$KERNEL_INSTALL_ENTRY_TOKEN is set for the plugins to the desired entry "token" to use. It's an identifier that shall be used to identify the local installation, and is often the machine ID, i.e. same as $KERNEL_INSTALL_MACHINE_ID, but might also be a different type of identifier, for example a fixed string or the ID=, IMAGE_ID= values from /etc/os-release. The string passed here will be used to name Boot Loader Specification entries, or the directories the kernel image and initial RAM disk images are placed into.

Note that while $KERNEL_INSTALL_ENTRY_TOKEN and $KERNEL_INSTALL_MACHINE_ID are often set to the same value, the latter is guaranteed to be a valid 32 character ID in lowercase hexadecimals while the former can be any short string. The entry token to use is read from /etc/kernel/entry-token, if it exists. Otherwise a few possible candidates below $BOOT are checked for Boot Loader Specification Type 1 entry directories, and if found the entry token is derived from that. If that is not successful, $KERNEL_INSTALL_MACHINE_ID is used as fallback.

$KERNEL_INSTALL_BOOT_ROOT is set for the plugins to the absolute path of the root directory (mount point, usually) of the hierarchy where boot loader entries, kernel images, and associated resources should be placed. This usually is the path where the XBOOTLDR partition or the ESP (EFI System Partition) are mounted, and also conceptually referred to as $BOOT. Can be overridden by setting $BOOT_ROOT (see below).

$KERNEL_INSTALL_LAYOUT=bls|other|... is set for the plugins to specify the installation layout. Defaults to bls if $BOOT/ENTRY-TOKEN exists, or other otherwise. Additional layout names may be defined by convention. If a plugin uses a special layout, it's encouraged to declare its own layout name and configure layout= in install.conf upon initial installation. The following values are currently understood:

bls

other

$KERNEL_INSTALL_INITRD_GENERATOR is set for plugins to select the initrd generator. This may be configured as initrd_generator= in install.conf, see below.

$KERNEL_INSTALL_STAGING_AREA is set for plugins to a path to a directory. Plugins may drop files in that directory, and they will be installed as part of the loader entry, based on the file name and extension.

Environment variables understood by kernel-install¶

$KERNEL_INSTALL_CONF_ROOT can be set to override the location of the configuration files read by kernel-install. When set, install.conf, entry-token, and other files will be read from this directory.

$KERNEL_INSTALL_PLUGINS can be set to override the list of plugins executed by kernel-install. The argument is a whitespace-separated list of paths. "KERNEL_INSTALL_PLUGINS=:" may be used to prevent any plugins from running.

$MACHINE_ID can be set for kernel-install to override $KERNEL_INSTALL_MACHINE_ID, the machine ID.

$BOOT_ROOT can be set for kernel-install to override $KERNEL_INSTALL_BOOT_ROOT, the installation location for boot entries.

The last two variables may also be set in install.conf. Variables set in the environment take precedence over the values specified in the config file.