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linux上查看系统的物理/虚拟地址的数据： 查看物理地址： 首先下载：apt-get install devmem2 使用: devmem2 命令 例如: devmem2 0x40402000 可以查看系统上面的实际的物理地址0x40402000的数据：32bit = 4byte 打印如下： /dev/mem opened. Memory mapped at address 0xb6f67000. Value at address 0x40402000 (0xb6f67000): 0xC6FBCB00 这里地址的实际值是： 0xC6FBCB00， 这个地址通过MMU映射到虚拟地址0xb6f67000 注意并不是所有的地址都可以访问的。 源代码：
/*
* devmem2.c: Simple program to read/write from/to any location in memory.
*
* Copyright (C) 2000, Jan-Derk Bakker ([email protected])
*
*
* This software has been developed for the LART computing board
* (http://www.lart.tudelft.nl/). The development has been sponsored by
* the Mobile MultiMedia Communications (http://www.mmc.tudelft.nl/)
* and Ubiquitous Communications (http://www.ubicom.tudelft.nl/)
* projects.
*
* The author can be reached at:
*
* Jan-Derk Bakker
* Information and Communication Theory Group
* Faculty of Information Technology and Systems
* Delft University of Technology
* P.O. Box 5031
* 2600 GA Delft
* The Netherlands
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \
__LINE__, __FILE__, errno, strerror(errno)); exit(1); } while(0)
#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE - 1)
int main(int argc, char **argv) {
int fd;
void *map_base, *virt_addr;
unsigned long read_result, writeval;
off_t target;
int access_type = 'w';
if(argc 2)
access_type = tolower(argv[2][0]);
if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL;
printf("/dev/mem opened.\n");
fflush(stdout);
/* Map one page */
map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK);
if(map_base == (void *) -1) FATAL;
printf("Memory mapped at address %p.\n", map_base);
fflush(stdout);
virt_addr = map_base + (target & MAP_MASK);
switch(access_type) {
case 'b':
read_result = *((unsigned char *) virt_addr);
break;
case 'h':
read_result = *((unsigned short *) virt_addr);
break;
case 'w':
read_result = *((unsigned long *) virt_addr);
break;
default:
fprintf(stderr, "Illegal data type '%c'.\n", access_type);
exit(2);
}
printf("Value at address 0x%X (%p): 0x%X\n", target, virt_addr, read_result);
fflush(stdout);
if(argc > 3) {
writeval = strtoul(argv[3], 0, 0);
switch(access_type) {
case 'b':
*((unsigned char *) virt_addr) = writeval;
read_result = *((unsigned char *) virt_addr);
break;
case 'h':
*((unsigned short *) virt_addr) = writeval;
read_result = *((unsigned short *) virt_addr);
break;
case 'w':
*((unsigned long *) virt_addr) = writeval;
read_result = *((unsigned long *) virt_addr);
break;
}
printf("Written 0x%X; readback 0x%X\n", writeval, read_result);
fflush(stdout);
}
if(munmap(map_base, MAP_SIZE) == -1) FATAL;
close(fd);
return 0;
}
查看虚拟地址的数据 devkmem：查看虚拟地址的数据 源代码：
#include
#include
#include
#include
#include
#include
#include
#include
#define DEVKMEM "/dev/kmem"
#define PAGE_SIZE 0x1000
#define PAGE_MASK (~(PAGE_SIZE-1))
int main(int argc, char* argv[])
{
int fd;
char *mbase;
char read_buf[10];
unsigned int regAddr;
varAddr = strtoul(argv[1], 0, 16);
unsigned int ptr = varAddr & ~(PAGE_MASK);
fd = open(DEVKMEM, O_RDONLY);
if (fd == -1) {
perror("open");
exit(-1);
}
mbase = mmap(0,PAGE_SIZE,PROT_READ,MAP_SHARED,fd, (varAddr & PAGE_MASK));
if (mbase == MAP_FAILED) {
printf("map failed %s\n",strerror(errno));
}
printf("varAddr = 0x%X \n", varAddr);
printf("mapbase = 0x%X \n", (unsigned int)mbase);
printf("value = 0x%X \n",*(unsigned int*)(mbase+ptr));
close(fd);
munmap(mbase,PAGE_SIZE);
return 0;
}
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