root/tools/testing/selftests/intel_pstate/msr.c

DEFINITIONS

1. main

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <math.h>
   3 #include <unistd.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <sys/types.h>
   7 #include <sys/stat.h>
   8 #include <fcntl.h>
   9 #include <sys/timeb.h>
  10 #include <sched.h>
  11 #include <errno.h>
  12 
  13 
  14 int main(int argc, char **argv) {
  15         int cpu, fd;
  16         long long msr;
  17         char msr_file_name[64];
  18 
  19         if (argc != 2)
  20                 return 1;
  21 
  22         errno = 0;
  23         cpu = strtol(argv[1], (char **) NULL, 10);
  24 
  25         if (errno)
  26                 return 1;
  27 
  28         sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
  29         fd = open(msr_file_name, O_RDONLY);
  30 
  31         if (fd == -1) {
  32                 perror("Failed to open");
  33                 return 1;
  34         }
  35 
  36         pread(fd, &msr,  sizeof(msr), 0x199);
  37 
  38         printf("msr 0x199: 0x%llx\n", msr);
  39         return 0;
  40 }