<para>If <varname>MACHINE_ID=</varname> is set and not empty, it will be used as <replaceable>MACHINE-ID</replaceable>,
overriding any automatic detection attempts. The value must be a valid machine ID (32 hexadecimal characters).</para>
+
+ <para><varname>KERNEL_INSTALL_MACHINE_ID=</varname> is set for the plugins to the desired <replaceable>MACHINE-ID</replaceable> –
+ either 32 hexadecimal characters or the special value <literal>Default</literal>.</para>
+ <para><varname>KERNEL_INSTALL_BOOT_ROOT=</varname> is set for the plugins to the root directory (mount point, usually) of the hierarchy
+ where boot-loader entries, kernel images, and associated resources should be placed. Can be overriden by setting <varname>BOOT_ROOT=</varname>.</para>
</refsect1>
<refsect1>