Xen的内存空间

32位PAE模式X86架构下，Xen占用了最顶部的64MB的线性地址空间。分布如下：

IOREMAP_VIRT_END :0
IOREMAP_VIRT_START :FFC00000

 

 

DIRECTMAP_VIRT_END :FFC00000
DIRECTMAP_VIRT_START :FF000000

 

MAPCACHE_VIRT_END :FF000000
MAPCACHE_VIRT_START :FEC00000

 

 

PERDOMAIN_VIRT_END :FF000000
PERDOMAIN_VIRT_START :FE800000

 

SH_LINEAR_PT_VIRT_END :FE800000
SH_LINEAR_PT_VIRT_START :FE000000

 

LINEAR_PT_VIRT_END :FE000000
LINEAR_PT_VIRT_START :FD800000

 

RDWR_MPT_VIRT_END :FD800000
RDWR_MPT_VIRT_START :FC800000

 

FRAMETABLE_VIRT_END :FC800000
FRAMETABLE_VIRT_START :F6800000

 

RO_MPT_VIRT_END :F6800000
RO_MPT_VIRT_START :F5800000

 

 

非PAE模式，分布如下：

I/O Remapping Area:I/O重映射

IOREMAP_VIRT_END :0
IOREMAP_VIRT_START :FFC00000

 

Direct-map: 直接映射区域

DIRECTMAP_VIRT_END :FFC00000
DIRECTMAP_VIRT_START :FF000000

 

Map Cache:映射缓存，用于缓存Domain地址映射 

MAPCACHE_VIRT_END :FF000000
MAPCACHE_VIRT_START :FEC00000

 

Per-Domain Mappings: 用于每个Domain地址映射

PERDOMAIN_VIRT_END :FF000000
PERDOMAIN_VIRT_START :FE800000

 

Shadow Linear Pagetable: 映射影子页目录和页表

SH_LINEAR_PT_VIRT_END :FE800000
SH_LINEAR_PT_VIRT_START :FE400000

 

Guest Linear Pagetable: 映射当前Guest OS的页表结构，包括页目录和页表

LINEAR_PT_VIRT_END :FE400000
LINEAR_PT_VIRT_START :FE000000

 

Machine-to-physical Translation Table(RW): 可写M2P表，能被Xen读写，Guest OS不能访问

RDWR_MPT_VIRT_END :FE000000
RDWR_MPT_VIRT_START :FDC00000

 

Frame-info Table: 系统物理页信息表，对应frame_table数组

FRAMETABLE_VIRT_END :FDC00000
FRAMETABLE_VIRT_START :FC400000

 

Machine-to-physical Translation Table(RO): 只读M2P表，能够被Guest OS访问。

RO_MPT_VIRT_END :FC400000
RO_MPT_VIRT_START :FC000000

 

 

 

 

附：

1、Xen堆(Xenheap)区域即直接映射区域(Direct-map)，大小为12 MB。Xen堆和传统操作系统的内核相当，在系统初始化时占用了机器物理地址空间的前面12MB。

2、

 

#include <stdio.h>#include <stdlib.h> #define IOREMAP_MBYTES 4#define DIRECTMAP_MBYTES 12#define MAPCACHE_MBYTES 4#define PERDOMAIN_MBYTES 8#ifdef CONFIG_X86_PAE# define LINEARPT_MBYTES 8# define MACHPHYS_MBYTES 16 /* 1 MB needed per 1 GB memory */# define FRAMETABLE_MBYTES (MACHPHYS_MBYTES * 6)#else# define LINEARPT_MBYTES 4# define MACHPHYS_MBYTES 4# define FRAMETABLE_MBYTES 24#endif#define IOREMAP_VIRT_END 0UL#define IOREMAP_VIRT_START (IOREMAP_VIRT_END - (IOREMAP_MBYTES<<20))#define DIRECTMAP_VIRT_END IOREMAP_VIRT_START#define DIRECTMAP_VIRT_START (DIRECTMAP_VIRT_END - (DIRECTMAP_MBYTES<<20))#define MAPCACHE_VIRT_END DIRECTMAP_VIRT_START#define MAPCACHE_VIRT_START (MAPCACHE_VIRT_END - (MAPCACHE_MBYTES<<20))#define PERDOMAIN_VIRT_END DIRECTMAP_VIRT_START#define PERDOMAIN_VIRT_START (PERDOMAIN_VIRT_END - (PERDOMAIN_MBYTES<<20))#define SH_LINEAR_PT_VIRT_END PERDOMAIN_VIRT_START#define SH_LINEAR_PT_VIRT_START (SH_LINEAR_PT_VIRT_END - (LINEARPT_MBYTES<<20))#define LINEAR_PT_VIRT_END SH_LINEAR_PT_VIRT_START#define LINEAR_PT_VIRT_START (LINEAR_PT_VIRT_END - (LINEARPT_MBYTES<<20))#define RDWR_MPT_VIRT_END LINEAR_PT_VIRT_START#define RDWR_MPT_VIRT_START (RDWR_MPT_VIRT_END - (MACHPHYS_MBYTES<<20))#define FRAMETABLE_VIRT_END RDWR_MPT_VIRT_START#define FRAMETABLE_VIRT_START (FRAMETABLE_VIRT_END - (FRAMETABLE_MBYTES<<20))#define RO_MPT_VIRT_END FRAMETABLE_VIRT_START#define RO_MPT_VIRT_START (RO_MPT_VIRT_END - (MACHPHYS_MBYTES<<20))#define XENHEAP_DEFAULT_MB (DIRECTMAP_MBYTES)#define DIRECTMAP_PHYS_END (DIRECTMAP_MBYTES<<20)int main( ) { FILE *fp; int a = 1; char c ='a'; fp=fopen("output.txt","w"); if(fp==NULL) { printf("Can not create the file！"); exit(0); } fprintf(fp,"IOREMAP_VIRT_END :%X/n",IOREMAP_VIRT_END); fprintf(fp,"IOREMAP_VIRT_START :%X/n/n",IOREMAP_VIRT_START); fprintf(fp,"DIRECTMAP_VIRT_END :%X/n",DIRECTMAP_VIRT_END); fprintf(fp,"DIRECTMAP_VIRT_START :%X/n/n",DIRECTMAP_VIRT_START); fprintf(fp,"MAPCACHE_VIRT_END :%X/n",MAPCACHE_VIRT_END); fprintf(fp,"MAPCACHE_VIRT_START :%X/n/n",MAPCACHE_VIRT_START); fprintf(fp,"PERDOMAIN_VIRT_END :%X/n",PERDOMAIN_VIRT_END); fprintf(fp,"PERDOMAIN_VIRT_START :%X/n/n",PERDOMAIN_VIRT_START); fprintf(fp,"SH_LINEAR_PT_VIRT_END :%X/n",SH_LINEAR_PT_VIRT_END); fprintf(fp,"SH_LINEAR_PT_VIRT_START :%X/n/n",SH_LINEAR_PT_VIRT_START); fprintf(fp,"LINEAR_PT_VIRT_END :%X/n",LINEAR_PT_VIRT_END); fprintf(fp,"LINEAR_PT_VIRT_START :%X/n/n",LINEAR_PT_VIRT_START); fprintf(fp,"RDWR_MPT_VIRT_END :%X/n",RDWR_MPT_VIRT_END); fprintf(fp,"RDWR_MPT_VIRT_START :%X/n/n",RDWR_MPT_VIRT_START); fprintf(fp,"FRAMETABLE_VIRT_END :%X/n",FRAMETABLE_VIRT_END); fprintf(fp,"FRAMETABLE_VIRT_START :%X/n/n",FRAMETABLE_VIRT_START); fprintf(fp,"RO_MPT_VIRT_END :%X/n",RO_MPT_VIRT_END); fprintf(fp,"RO_MPT_VIRT_START :%X/n/n",RO_MPT_VIRT_START); fclose(fp); return 0;}