Bootloaders in bootc

bootc uses bootupd by default to manage bootloader installation and configuration. bootupd is an external project that abstracts over bootloader installs and upgrades, providing a consistent interface for different bootloader types (e.g., GRUB, systemd-boot).

When you run bootc install, it invokes bootupctl backend install to install the bootloader to the target disk or filesystem. The specific bootloader configuration is determined by the container image and the target system's hardware.

Currently, bootc only runs bootupd during the installation process. It does not automatically run bootupctl update to update the bootloader after installation. This means that bootloader updates must be handled separately, typically by the user or an automated system update process.

For s390x, bootc uses zipl instead of bootupd.

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