hi this is srikanthpilli, i am using arm9-cortex A9 processor. i wanna find arm9 processor cpu id by using linux 'C'. how i will write C code? and how i will check code in arm9-cortex-A9 processor? please help this problem


sorry about my english

Thanks in Advance

srikanthpilli

You should be able to get the info you need by checking the content of /proc/cpuinfo

Thanks for your suggestion, this was done successfully in my console. but i wanna store getting data after type cat /proc/cpuinfu in some other location. so that's why i am asking you how to write code in linux C and how i will store that data in file.


thanks
srikanthpilli

Hello srikanth,

Here is the solution of your problem, maybe this code can help you:

#include <stdio.h>

int main(int argc, char **argv)
{
unsigned eax, ebx, ecx, edx;

eax = 1; /* processor info and feature bits */
native_cpuid(&eax, &ebx, &ecx, &edx);

printf("stepping %d\n", eax & 0xF);
printf("model %d\n", (eax >> 4) & 0xF);
printf("family %d\n", (eax >> 8) & 0xF);
printf("processor type %d\n", (eax >> 12) & 0x3);
printf("extended model %d\n", (eax >> 16) & 0xF);
printf("extended family %d\n", (eax >> 20) & 0xFF);
}


And let us know if this code works for you.

And this command will tell you Api usage:

/usr/bin/lsb_release -a

I meant you can open /proc/cpuinfo inside your C program to get and store the data.
But if Satyaveer Arya code works, it looks much better.

Yes ofcourse you can open /proc/cpuinfo file inside C program to get and store data in some other file.

---------- Post added 18th Dec 2011 at 10:05 AM ----------

Try the above code given by me and please share the results with us.

after save the above program with cpuid.c, i tried with gcc cpuid.c, it shows the following error.

i.e
/tmp/cc2NybTs.o: In function `main':
cpuid.c.text+0x31): undefined reference to `native_cpuid'
collect2: ld returned 1 exit status

Satyaveer Arya's code seems to have been brought from this page:
Stack Overflow: Getting Machine Serial number and CPU Id using c/c++ in Linux

That page provides the definition for native_cpuid() that should be included as part of the C source file.

In addition, the solution on the page links to a wikipedia article (Wikipedia: CPUID) that describes bit ranges and their meanings for the various processor registers that are read by native_cpuid().

As far as I can tell, the above examples are specific to x86 architecture, and will not work on ARM A9.

Obviously, A9 does have a mechanism for obtaining processor and architecture information; you might be able to use inline assembly to do that. However, it seems to me there are a lot of details to worry about (looking at some of the kernel sources), enough so that it makes more sense to let the kernel people worry about detecting the features, and just read /proc/cpuinfo in userspace programs instead.

If you are worried about memory usage or similar issues, you can use low-level I/O (unistd.h) to read /proc/cpuinfo to a small buffer, splitting each line into name : value pairs for parsing. Parse each pair, perhaps using a helper function for each different name, populating a structure describing the current CPU architecture with the results. This may sound a bit complicated, but it is not at all difficult to do. If you are only interested in specific capabilities (as in whether certain features are available or not), it is even easier.

If you'd like to see some example code, please show the /proc/cpuinfo file from your ARM Cortex A9 first.