> As per above, usb_keyboard was linked via grub-mkimage - the keyboard/mouse do not work with/without any usb modules
> --------------------------------------
> I compiled grub from bzr a couple of days back.
> 
> I didn't use grub-install as I'm nervous about writing to the mbr and not being able to boot the mac mini at all.

If you don't supply any direct argument and explicitly add
--target=x86_64-efi then you can be sure it won't overwrite any MBR

> 
> Anyway, I can still boot using both hfs+ partition /efi/grub/grub.efi and fat partition /EFI/BOOT/ BOOTX64.EFI, but the result is the same - no usb keyboard and no usb mouse.
> 

Aa I said before: lack of USB keyboard/mouse in Linux can't be of any
GRUB wrongdoing since Linux uses its own USB driver.

> Note that I also do not get graphics, but it boots "blind" without problems.
> 

Does videotest work?

-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko