los_vm_page.h

/*
 * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
 * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
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#ifndef __LOS_VM_PAGE_H__
#define __LOS_VM_PAGE_H__

#include "los_typedef.h"
#include "los_bitmap.h"
#include "los_list.h"
#include "los_atomic.h"

#ifdef __cplusplus
#if __cplusplus
extern "C" {
#endif /* __cplusplus */
#endif /* __cplusplus */
/******************************************************************************
 虚拟内存体现的是程序对内存资源的需求，而物理内存是对该请求的供应。
 伙伴算法的思想是：把内存中连续的空闲页框空间看成是空闲页框块，并按照它们的大小（连续页框的数目）分组
******************************************************************************/
//注意: vmPage 中并没有虚拟地址，只有物理地址
typedef struct VmPage {	//物理页框描述符
    LOS_DL_LIST         node;        /**< vm object dl list */ //虚拟内存节点,通过它挂/摘到全局g_vmPhysSeg[segID]->freeList[order]物理页框链表上
    PADDR_T             physAddr;    /**< vm page physical addr */		//物理页框起始物理地址,只能用于计算,不会用于操作(读/写数据==)
    Atomic              refCounts;   /**< vm page ref count */			//被引用次数,共享内存会被多次引用
    UINT32              flags;       /**< vm page flags */				//页标签，同时可以有多个标签（共享/引用/活动/被锁==）
    UINT8               order;       /**< vm page in which order list */	//被安置在伙伴算法的几号序列(              2^0,2^1,2^2,...,2^order)
    UINT8               segID;       /**< the segment id of vm page */	//所属段ID
    UINT16              nPages;      /**< the vm page is used for kernel heap */	//分配页数,标识从本页开始连续的几页将一块被分配
} LosVmPage;//注意:关于nPages和order的关系说明,当请求分配为5页时,order是等于3的,因为只有2^3才能满足5页的请求

extern LosVmPage *g_vmPageArray;//物理页框(page frame)池,在g_vmPageArray中:不可能存在两个物理地址一样的物理页框,
extern size_t g_vmPageArraySize;//物理总页框(page frame)数

LosVmPage *LOS_VmPageGet(PADDR_T paddr);
VOID OsVmPageStartup(VOID);

#ifdef __cplusplus
#if __cplusplus
}
#endif /* __cplusplus */
#endif /* __cplusplus */

#endif /* __LOS_VM_PAGE_H__ */