Learning source code of utility 'devmem2'
C Dev Infection
- Sep 04, 2016 Actually the numbers are read using C strtoul function, so it will interpret numbers like 0123 as octal! Probably not what you want! NOTE: It is not guaranteed that any physical address can be accessed by this program. Validity of the ADDRESS may be checked by the OS. See the source of the kernel driver which provides the /dev/mem device for.
- Dec 18, 2008 How to map to Physical Address by using mmap in Linux Showing 1-9 of 9 messages. How to map to Physical Address by using mmap in Linux: khadar: 12/18/08 6:08 AM: Hi, I want to use mmap system call from User space to map the user space file(/dev/mem) to memory and write some file at that address. How to map to Physical Address by using.
- Random Access Memory (RAM) is a block device, why Linux uses a character device file instead of a block device file for user-processes to interface with /dev/mem? $ ls -l /dev/mem crw-r- 1 root kmem 1, 1 Jul 24 19:05 /dev/mem.
- In the Linux kernel source, the code providing per-process entries in /proc is in fs/proc/base.c, and the function to read from /proc/$pid/mem is memread. The additional check is performed by checkmempermission. Here's some sample C code to attach to a process and read a chunk its of mem file (error checking omitted).
/dev/mem is a character device file that is an image of the main memory of the computer. It may be used, for example, to examine (and even patch) the system. It may be used, for example, to examine (and even patch) the system. Sep 04, 2016 Creating copies or links with different names (ex. 'mem' instead of 'devmem') to the executable file is ok.Runtime dependencies.: only the C library (libc.so, etc.) unless built statically. This program needs that access to /dev/mem file is enabled in the kernel.
Linux C /dev/mem
Refer to 'AMDM37x Multimedia Device Silicon Revision 1.x Technical Reference Manual___sprugn4m.pdf'
Dev C++ Linux Mint
Page 2434: For OMAP37x (Beagle Board's processor), its pin gpmc_ncs4 (Mode 0, CONTROL_PADCONF_GPMC_NCS3[31:16]) can also be switched to gpt9_pwm_evt (Mode 3), whose physical address is 0x4800 20B4.
I run below command on Beagle Board(OMAP ):ubuntu@omap:~/tom/test$ sudo devmem2 0x480020b4 w/dev/mem opened.Memory mapped at address 0xb6f4b000.Value at address 0x480020B4 (0xb6f4b0b4): 0x180018
Linux C Dev Mem Free
Refer to page 2428: 0x18 (high 16 bits) means mode 0 = gpmc_ncs4. So to turn it to PWM functionality, (means mode 0 to mode 3 at high 16 bits), 0x18 -> 0x18+0x3=0x1bubuntu@omap:/tom/test$ sudo devmem2 0x480020b4 w 0x1b0018/dev/mem opened.Memory mapped at address 0xb6f31000.Value at address 0x480020B4 (0xb6f310b4): 0x180018Written 0x1B0018; readback 0x1B0018ubuntu@omap:/tom/test$ sudo devmem2 0x480020b4 w/dev/mem opened.Memory mapped at address 0xb6fa7000.Value at address 0x480020B4 (0xb6fa70b4): 0x1B0018