passing options to grub in xen,openfirmware and efi

[Olaf Hering]

Is there a way to pass options to grub in a Xen PV domU, in openfirmware
and in EFI environment?

In a PV domU arguments can be passed to the specified
kernel="/path/file" with the extra="what ever" option.
In openfirmware the arguments may come from the /boot/chosen node.
In EFI it may be possible as well, not my area of expertise.
In the wellknown dumb i386 BIOS no such way exist.

In case grub has code to evalute these things, how can such arguements
be used within grub.cfg? Where is that documented?

Thanks,

Olaf