git clone https://github.com/tianocore/edk2.git
cd edk2
OvmfPkg/build.sh -a IA32 -n 4
cp Build/OvmfX64/DEBUG_GCC4?/FV/OVMF.fd bios32.bin
OvmfPkg/build.sh -a X64 -n 4
cp Build/OvmfX64/DEBUG_GCC4?/FV/OVMF.fd bios64.bin
qemu-system-x86_64 -bios /path/to/bios32.bin ....<other qemu options>....
qemu-system-x86_64 -bios /path/to/bios64.bin ....<other qemu options>....
qemu-system-i386 -bios /path/to/bios32.bin ....<other qemu options>....