Test variations of xgetbv

xgetbv_test.c

#include <stdio.h>

static unsigned long long _xgetbv(unsigned int index){
      unsigned int eax, edx;

      /* original code
      __asm__ __volatile__("xgetbv" : "=a"(eax), "=d"(edx) : "c"(index));
      */

      /* Nokia code */
      __asm__ __volatile__(".byte 0x0f, 0x01, 0xd0"
            : "=a"(eax), "=d"(edx) : "c"(index));

      /* modified code, segfaults
      __asm__ __volatile__ (".byte 0x0f\n");
      __asm__ __volatile__ (".byte 0x01\n");
      __asm__ __volatile__ (".byte 0xd0\n" // xgetbv instruction
            : "=a"(eax), "=d"(edx) : "c"(index));
      */

      return ((unsigned long long)edx << 32) | eax;
}

int main() {
      printf("666 is %i\n", _xgetbv(666));
}