Manpages - kernel-install.8

kernel-install - Add and remove kernel and initramfs images to and from /boot

kernel-install COMMAND [OPTIONS…] KERNEL-VERSION KERNEL-IMAGE [/INITRD-FILE/…]

kernel-install is used to install and remove kernel and initramfs images to and from the boot loader partition, referred to as $BOOT here. It will usually be one of boot, efi, or boot/efi, see below.

kernel-install will execute the files located in the directory usr/lib/kernel/install.d and the local administration directory etc/kernel/install.d. All files are collectively sorted and executed in lexical order, regardless of the directory in which they live. However, files with identical filenames replace each other. Files in etc/kernel/install.d take precedence over files with the same name in usr/lib/kernel/install.d. This can be used to override a system-supplied executables with a local file if needed; a symbolic link in etc/kernel/install.d with the same name as an executable in usr/lib/kernel/install.d, pointing to /dev/null, disables the executable entirely. Executables must have the extension “.install”; other extensions are ignored.

An executable should return 0 on success. It may also return 77 to cause the whole operation to terminate (executables later in lexical order will be skipped).

The following commands are understood:

add */KERNEL-VERSION/ KERNEL-IMAGE [*/INITRD-FILE/* …]*

This command expects a kernel version string and a path to a kernel image file as arguments. kernel-install calls the executables from /usr/lib/kernel/install.d/*.install and /etc/kernel/install.d/*.install with the following arguments:

#+begin_quote

      add KERNEL-VERSION $BOOT/MACHINE-ID/KERNEL-VERSION/ KERNEL-IMAGE [INITRD-FILE ...]

Three default plugins execute the following operations in this case:

·

00-entry-directory.install creates the directory $BOOT//MACHINE-ID///KERNEL-VERSION// if $BOOT//MACHINE-ID// already exists.

·

50-depmod.install runs *depmod*(8) for the KERNEL-VERSION.

·

90-loaderentry.install copies KERNEL-IMAGE to $BOOT//MACHINE-ID///KERNEL-VERSION//linux. If an INITRD-FILE is provided, it also copies INITRD-FILE to $BOOT//MACHINE-ID///KERNEL_VERSION///INITRD-FILE/. It also creates a boot loader entry according to the Boot Loader Specification[1] in $BOOT/loader/entries//MACHINE-ID/-KERNEL-VERSION.conf. The title of the entry is the PRETTY_NAME parameter specified in etc/os-release or /usr/lib/os-release (if the former is missing), or “Linux /KERNEL-VERSION“, if unset.

If the entry directory $BOOT//MACHINE-ID///KERNEL-VERSION// does not exist, this plugin does nothing.

#+end_quote

*remove */KERNEL-VERSION/

This command expects a kernel version string as single argument. This calls executables from /usr/lib/kernel/install.d/*.install and /etc/kernel/install.d/*.install with the following arguments:

#+begin_quote

      remove KERNEL-VERSION $BOOT/MACHINE-ID/KERNEL-VERSION/

Afterwards, kernel-install removes the directory $BOOT//MACHINE-ID///KERNEL-VERSION// and its contents.

Two default plugins execute the following operations in this case:

·

50-depmod.install removes the files generated by depmod for this kernel again.

·

90-loaderentry.install removes the file $BOOT/loader/entries//MACHINE-ID/-KERNEL-VERSION.conf.

#+end_quote

The partition where the kernels and Boot Loader Specification[1] snippets are located is called $BOOT. kernel-install determines the location of this partition by checking efi, boot, and boot/efi in turn. The first location where $BOOT/loader/entries/ or $BOOT/$MACHINE_ID/ exists is used.

The following options are understood:

-v, –verbose

Output additional information about operations being performed.

-h, –help

Print a short help text and exit.

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

If every executable returns 0 or 77, 0 is returned, and a non-zero failure code otherwise.

/usr/lib/kernel/install.d/*.install /etc/kernel/install.d/*.install

Drop-in files which are executed by kernel-install.

/etc/kernel/cmdline /proc/cmdline

Read by 90-loaderentry.install. The content of the file /etc/kernel/cmdline specifies the kernel command line to use. If that file does not exist, /proc/cmdline is used.

/etc/kernel/tries

Read by 90-loaderentry.install. If this file exists a numeric value is read from it and the naming of the generated entry file is slightly altered to include it as $BOOT/loader/entries//MACHINE-ID/-KERNEL-VERSION/+/TRIES.conf. This is useful for boot loaders such as *systemd-boot*(7) which implement boot attempt counting with a counter embedded in the entry file name.

/etc/machine-id

The content of this file specifies the machine identification MACHINE-ID. If it cannot read /etc/machine-id, kernel-install will use “Linux” as the machine ID instead.

/etc/os-release /usr/lib/os-release

The content of the file specifies the operating system title PRETTY_NAME.

machine-id*(5), *os-release*(5), *depmod*(8), *systemd-boot*(7), *Boot Loader Specification[1]

1.

Boot Loader Specification

https://systemd.io/BOOT_LOADER_SPECIFICATION