An extremely lightweight UEFI SDK that uses a standard clang instalation to compile C directly into UEFI applications. It uses the gnu-efi library and header files, but does not use any of its toolchain. I've also included a build of edk2 to make it easy to run the UEFI applications in qemu.
This is largely based off of the the setup outlined here https://wiki.osdev.org/UEFI_Bare_Bones but with a Makefile that deals with a lot of the boring stuff around compiling and packaging UEFI applications, and better integration with gnu-efi.
makecompiles.cfiles in the current directory into an efi application, it will then package that into a FAT-formatted image ready to run in qemu.make qemuruns the compiled image in qemu.make cleandeletes the files created by the build process.make update_edk2will download and update to the latest version of edk2.
├── hello_world.c # A Hello world example program
├── LICENSE # BSD 2-Clause License
├── Makefile # Makefile for GNU Make
├── README.md # Instructions
└── sdk
├── edk2.git-ovmf-x64-0-20200309.1355.g6e9bd495b3.noarch # A build of edk2 from Tianocore
└── gnu-efi # A fork of gnu-efi