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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2026 Richard Qin
*/
#pragma once
#include "common/types.h"
#include "kernel/spinlock.h"
#include "kernel/fdt.h" // For g_devices
// Physical Memory Layout Definition
#define KERNBASE 0x80000000
// Dynamic memory size from FDT
// Default to 128MB if FDT not present/parsed
extern uint64 g_phys_size;
#define PHYSIZE (g_phys_size)
#define PHYSTOP (KERNBASE + PHYSIZE)
// Buddy System Max Order
// Order 10 => 2^10 pages = 1024 * 4KB = 4MB contiguous block
// Order 11 => 2^11 pages = 8MB
#define MAX_ORDER 11
// Page flag
#define PG_used 0x01 // This page is occupied
#define PG_reserved 0x02 // This page is reserved (kernel code/data, DTB, MemMap)
// Physical Page Metadata Structure
struct Page
{
uint8 flags; // Page Status (PG_used, PG_reserved)
uint8 order; // If it is the first page of a free block, record the order of the current block
uint16 refcnt; // Reference Counting
struct Page *next; // Free list pointer (points to the next free block of the same size)
struct Page *prev; // Doubly linked list (easy to remove)
};
namespace PMM
{
// Initialize physical memory management
void init();
// Core Allocation Interface (Buddy System)
// order: 0 ~ MAX_ORDER-1
void *alloc_pages(int order);
void free_pages(void *pa, int order);
// Compatible with old interface (allocate single page with order=0 and automatically reset to zero)
void *alloc_page();
void free_page(void *pa);
// Helper function
struct Page *pa_to_page(uint64 pa);
uint64 page_to_pa(struct Page *page);
// Debug information
void print_free_lists();
}
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