The current version of GRUB does not allow you to pass more than 256 characters at the boot prompt. If many parameters must be specified, some of them can be put into a special file to reduce the number of characters. The file must be specified as kernel parameter as follows:
info=<Protocol://path_to_info_file>
Not every boot parameter can be configured via info files. For instance, it is not possible to set up network parameters if the info file itself is located on a network repository.
The following example shows an info file:
insecure: 1 autoupgrade: 1 dud: http://10.10.10.221/info/au_oes11/unattended_migration.dud