Newbie need help building pixhawk code

i just cloned the ardupilot project and I’m trying to compile using make command. It runs for a while then errors out; not sure if I’m missing something. My first instinct tells me a submodule is missing but I did initialize the pixhawk submodules. it seems like i’m getting a lot of undefined references. one of the errors reads as follows: "make[2] ***[path/modules/px4firmware/build/pl4io-v2_default.build/firmware.elf} Error 1. Thanks.

git submodule update --init in the main repo directory will set it up correctly