> __asm__("movl $0xa, %%eax" : ); // Moves 0xA in EAX: CPUID input param to
> get performance monitoring info
> __asm__("cpuid" : );
> __asm__("movl %%eax, %0" :"=r"(resultEax) : :);
> __asm__("movl %%ebx, %0" :"=r"(resultEbx) : :);
> __asm__("movl %%edx, %0" :"=r"(resultEdx) : :);
This is not a correct way to write gcc inline assembler, you cannot
assume that registers stay valid between assembler statements.
The easiest way is to use the macros from cpuid.h.
Here's a valid test program. Various Intel CPUs report REF_TSC (2) not
there, but it's really there, just not quite following the
descriptions. Other than that the architectural events are generally
available.
#include <cpuid.h>
#include <stdio.h>
int main()
{
unsigned a, b, c, d;
/* check __get_cpuid_max here */
__cpuid(10, a, b, c, d);
printf("eax: %x ebx %x ecx %x edx %x\n", a, b, c, d);
int i;
for (i = 0; i < 10; i++)
if (b & (1 << i))
printf("event %d not supported\n", i);
return 0;
}
-Andi
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