Linux Kernel Memory Detection via E820 Mechanism

This article details the Linux kernel's memory detection process during boot, focusing on the E820 mechanism. Firmware communicates available memory ranges to the kernel through interrupt 15H with E820 opcode, which the kernel stores in boot_params.e820_table and later transfers to a global e820_table structure.

The kernel then prints memory maps showing usable and reserved regions. Code examples illustrate the detect_memory_e820 function that handles interrupt handling and data parsing. The process ensures the kernel understands physical memory layout before allocating resources via memblock and buddy allocator systems.

Key steps include firmware initialization, E820 interrupt handling, memory mapping storage, and subsequent memory management by kernel subsystems. The article also demonstrates how to inspect these results using dmesg commands.