Question

I’m reading this course on the structure of an executable and it says there are three data sections in an executable:

• code section — where the instructions are stored
• data section
  • .data — stores initialized global data
  • .bss — stores uninitialized global data
  • .rodata — stores read-only data, such as literals

My question is, why is the distinction made between initialized and uninitialized global data?

(We use C in class, but I guess this is a language agnostic subject.)

Answer 1

Image size. The program image has to contain the initialization data for .data, but it does not have to contain .bss.