On Sun, 8 Sep 2019 14:21:59 -0700
Samuel Sieb wrote:
BIOS boots using MBR,
> invokes Grub, which then (optionally) invokes UEFI to boot Windows. Or
> is this not possible?
You can't because the EFI services would not be available.
Could you have a separate grub instance that is UEFI and chainload
over to it?