Liangxu Linux

Jun 30, 2025 · Fundamentals

How Linux Detects Physical Memory: Inside the E820 BIOS Interface

This article explains how the Linux kernel discovers physical memory during boot by invoking the BIOS interrupt 0x15 with the E820 function, how firmware (ACPI) provides the memory map, and how the kernel stores, prints, and later manages those memory regions using e820 tables, memblock, and the buddy allocator.