Compiling GRUB2

We have a working uBoot, and Kernel, work on UEFI GRUB booting is deprecated for the moment

We will use a pre-patched GRUB from as this will work out of the box on both the SurfaceRT and SurfaceRT2
You will need to have installed the compiler tools and libraries noted in Cross Compiling We recommend using a small Debian or Ubuntu machine or similar for development. A Raspberry PI4 is quite a good option.
git clone cd grub-2.04 ./bootstrap ./configure --with-platform=efi --target=arm-linux-gnueabihf --enable-mm-debug --enable-boot-time
Grub should compile successfully and you should see something similar to the results below: ******************************************************* GRUB2 will be compiled with following components: Platform: arm-efi With devmapper support: Yes With memory debugging: Yes With disk cache statistics: No With boot time statistics: Yes efiemu runtime: No (not available on efi) grub-mkfont: Yes grub-mount: Yes starfield theme: Yes With DejaVuSans font from /usr/share/fonts/truetype/ttf-dejavu/DejaVuSans.ttf With libzfs support: No (need zfs library) Build-time grub-mkfont: Yes With unifont from /usr/share/fonts/X11/misc/unifont.pcf.gz With liblzma from -llzma (support for XZ-compressed mips images) *******************************************************
We now need to compile grub as below:
make cd grub-core ../grub-mkimage -O arm-efi -d . -o grub.efi -p / part_gpt part_msdos ntfs ntfscomp hfsplus fat ext2 normal chain boot configfile linux gfxterm videoinfo efi_gop all_video video video_fb loadenv help reboot raid6rec raid5rec mdraid1x mdraid09 lvm diskfilter zfsinfo zfscrypt gcry_rijndael gcry_sha1 zfs true test sleep search search_fs_uuid search_fs_file search_label png password_pbkdf2 gcry_sha512 pbkdf2 part_apple minicmd memdisk lsacpi lssal lsefisystab lsefimmap lsefi disk keystatus jpeg iso9660 halt gfxterm_background gfxmenu trig bitmap_scale video_colors bitmap font fshelp efifwsetup echo terminal gettext efinet net priority_queue datetime bufio cat btrfs gzio lzopio crypto acpi extcmd mmap
The compiled grub.efi should now be in the current directory. Rename that file to boot.efi and copy to the root of a prepared USB for testing. A pre-compiled GRUB2 that will work on SurfaceRT and SurfaceRT2 is below: