[TF-A] PIE in tf-a

Hello tf experts, I've been studying the PIE support in TF-A recently, and there is one thing I'm confused about.

One is GOT table entry, is there any difference between this and .rela.dyn? I have done some homework, but I didn't find the answer. If someone can tell me, thanks a lot.

It looks like the current got segment is only 8 byte, so why must I need this section? Which kind of code will put into this section?