A simple 64bit UEFI application of Hello World! without using any UEFI toolkit.
If you use Fedora, you first need to install the mingw cross compiler by the following command.
yum install mingw64-gcc
If you use a distribution other than Fedora, find a 64bit mingw cross compiler, and set its name to "CC" in the Makefile.
Just typing the following command will compile and run the UEFI application on QEMU.
make qemu
The Makefile will download the current latest version of UEFI firmware (OVMF-X64-r15214.zip). If you can't download it, find the latest version from http://tianocore.sourceforge.net/wiki/OVMF