Memory Management

Physical Memory

MerlionOS uses a bitmap frame allocator to track 4 KiB physical page frames. The memory map is provided by the bootloader.

Virtual Memory

Each process has its own page table hierarchy (4-level paging on x86_64). The kernel maps itself into the upper half of every address space.

Key Features

• Demand paging: Pages are allocated lazily on first access via page fault handler
• Per-process page tables: Full isolation between user processes
• Slab allocator: Fixed-size object caching for frequently allocated kernel structures

Kernel Heap

The kernel heap uses a linked-list allocator bootstrapped early in boot, later supplemented by the slab allocator for common object sizes.

Shell command heap shows allocator statistics. memmap displays the physical memory map with color coding.