# ELF

## Basic structure

1. ELF header (0x00 - 0x40)
2. Program header (0x40 - 0x78)
3. Padding (0x78 - 0x80)
4. Machine code (0x80)

## Entry point

The entry point is defined in the first 64 bytes (ELF header).

## Base address

The minimum base address is controlled by the `mmap` settings:

```shell
sysctl vm.mmap_min_addr
```

Usually, this value is 65536 (0x1000).

## Initialization in Linux

ELF loader:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/binfmt_elf.c

ELF register definitions:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/include/asm/elf.h