Comment 13 for bug 1487365

Any idea which distro you saw supported this? Upstream grub explicitly does not support diskfilter writes (in other words, writing directly to /dev/md* devices, LVM, etc), but rather expects one to write to the underlying device, because there are just too many different cases in which writing directly to the top layer might break things.

My workaround (I'm still testing) would be to have grub-installer pick the underlying devices to install to.