Emulate your stm32f407 SoC with QEMU.
Install QEMU:
./install.sh
Build binaries:
mkdir build
cd build
../qemu/configure --target-list=aarch64-linux-user,arm-linux-user,arm-softmmu
make -j20
./build/qemu-system-arm -machine stm32f407g_disc -kernel kernel.elf -serial stdio
cd qemu
git add -N hw/arm/stm32f407g_disc.c
git diff > ../qemu.patch