What is the significance of ".note.ABI-tag" section in ELF?

Question

I see a .note.ABI-tag section when I objdump -h <binary> on a ELF file.

As per the ELF man page:

   .note.ABI-tag
             This section is used to declare the expected run-time ABI
             of the ELF image.  It may include the operating system name
             and its run-time versions.  This section is of type
             SHT_NOTE.  The only attribute used is SHF_ALLOC.

1. Is this section necessary?
2. What could be the side effects removing this section?
3. How to remove this section (a gcc flag) from ELF?

Answer 1

Could break the executable on some systems. It is supposed to give information on which kernel it's compatible with so if the binary's ABI are not compatible with the current kernel's ABI. See more information here https://refspecs.linuxfoundation.org/LSB_1.2.0/gLSB/noteabitag.html

However if your binary is not compiled for a specific kernel(not necessarily Linux as a lot of different targets use the ELF output) it doesn't matter and could just be cut if your goal is to reduce the executable's size. You should however be aware that it's already ignored if you are doing a objcopyfrom ELF to BIN.