This is where the message comes from: https://github.com/yast/yast-storage-ng/blob/master/src/lib/y2storage/boot_requirements_strategies/base.rb#L99 Here the disk space space is checked: https://github.com/yast/yast-storage-ng/blob/master/src/lib/y2storage/boot_requirements_strategies/base.rb#L134 Fallback for disk size requirements for /boot: https://github.com/yast/yast-storage-ng/blob/master/src/lib/y2storage/volume_specification_builder.rb#L88 (i.e. 100 MiB min size) AFAICS since there is no volume specification for /boot in control.xml, the fallback is used.