passing FDT(flattened device tree) to kernel during booting

Hello all, I read here (https://www.kernel.org/doc/Documentation/arm64/booting.txt https://www.kernel.org/doc/Documentation/arm64/booting.txt) the device tree blob location should be passed to the kernel during  arm64 booting through x0 register. But  I see many .dts files under arch/arm64/boot/dts for many commercial boards. Does this mean that 1) we are supposed to use one of these files in the bootloader program to setup the device tree and pass it to kernel? or 2) we can embed the device tree inside the kernel during kernel building and just use it during the boot? Any help will be appreciated. Chan Kim