Puzzle:where .rel sections get created in gas?

[Amker.Cheng]

Hi all:
    I am studying how gas works currently.
It seems if gas cannot resolve a relocation, the relocation will be
emit to the object file,
i.e. a relocation against section symbol ".text".
I think gas write relocation into object file in function
write_relocs, but where does
the relocation sections ".rel.text" itself get created and written
into object file?
I traced gas and found even at last statement of function
"write_object_file", which is
a call to "bfd_map_over_sections" , there is no ".rel.text" section in
abfd->sections list.

I must be missed something important, could anyone help me out?a tip
will be enough and appreciated.

Thanks in advance.
Reagrds.