"global main" in Assembly

Question

I came across this snippet of code:

section .text
    global  main    ;must be declared for linker (gcc)

and then there is a function called main after this line:

main:    ;tell linker entry point

but i don't seem to understand what global main means, and the comment doesn't seem to help much...

i am using this site as a reference to Assembly language programming.

i can analyse that main refers to the function main, but i don't understand the use of the global keyword...

thank you in advance...

Answer 1

global main basically means that the symbol should be visible to the linker because other object files will use it. Without it, the symbol main is considered local to the object file it's assembled to, and will not appear after the assembly file is assembled.