This patch implements badram filtering in GRUB. It's the same idea as in http://rick.vanrein.org/linux/badram/ but applied to GRUB.
The badram module sits between loaders (or other users like lsmmap) and filters the mmap entries, but only when user previously set the "badram" variable (whose syntax is the same as the one in badram patch for Linux).
NOTE this won't affect loadees that get the memory map from BIOS instead of from GRUB. This means it currently works for Multiboot and for the new/experimental Linux loader.