Implemented basic data access

build/elf/elf.md

@@ -1,12 +1,26 @@
 # ELF
 
-## File contents
+## Basic structure
 
-- ELF header
-- Program headers
-- Sections
-- Section headers
+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
+
+See `/lib/modules/$(uname -r)/build/arch/x86/include/asm/elf.h`.