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I was wondering if there was any resources available online that explains what happens with something, like printf of C, that explains what's going on in the very low level (BIOS/kernel calls)
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The printf function (the name comes from “print formatted”) prints a string on the screen using a “format string” that includes the instructions to mix several strings and produce the final string to be printed on the screen.
The printf() is a library function to send formatted output to the screen. The function prints the string inside quotations. To use printf() in our program, we need to include stdio.h header file using the #include <stdio.h> statement.
Printf in Assembly To call printf from assembly language, you just pass the format string in rdi as usual for the first argument, pass any format specifier arguments in the next argument register rsi, then rdx, etc.
"printf" is the name of one of the main C output functions, and stands for "print formatted". printf format strings are complementary to scanf format strings, which provide formatted input (lexing aka. parsing).
Linux:
printf() ---> printf() in the C library ---> write() in C library ---> write() system call in kernel.
To understand the interface between user space and kernel space, you will need to have some knowledge of how system calls work.
To understand what is going on at the lowest levels, you will need to analyze the source code in the kernel.
The Linux system call quick reference (pdf link) may be useful as it identifies where in the kernel source you might begin looking.
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