topic Detecting AVX in Intel® ISA Extensions

Detecting AVX

smidla — Wed, 24 Aug 2011 23:32:39 GMT

Hi!

I have a processor with the next brand string: "Intel Core i7 CPU M 620 @ 2.67GHz"

I have read that i7 CPU-s supports AVX technology. I wrote a program that detects cpu features by cpuid instructon. The program says that this processor DOESN'T supports AVX. When I check the result of cat /proc/cpuinfo in linux, avx is missing from the flags. What is the problem?

Thank You for Your help!

Detecting AVX

Brijender_B_Intel — Wed, 24 Aug 2011 23:49:40 GMT

I beleive this is a generation before Sandy Bridge. It does not support AVX. Processor with AVX support are mainly launched in 2011.
http://ark.intel.com/products/family/59143

Detecting AVX

smidla — Thu, 25 Aug 2011 00:16:44 GMT

I see. I browsed the list of "2nd Generation Core i7 Processors", but i didn't find processors with avx. Or in 2nd generation the avx is a default feature?

Detecting AVX

Brijender_B_Intel — Thu, 25 Aug 2011 00:41:50 GMT

Thats true. But you should have Win7 SP1 also. Win7 does not support AVX.

Detecting AVX

levicki — Sun, 09 Oct 2011 13:56:12 GMT

That CPU does not support AVX, just AES.
http://ark.intel.com/products/43560

Detecting AVX

Pourya_Shirazian — Wed, 26 Oct 2011 17:58:49 GMT

You can use this C code to detect AVX and other features on the processor:

[cpp]
#define OSXSAVEFlag (1UL<<27)
#define AVXFlag     ((1UL<<28)|OSXSAVEFlag)
#define FMAFlag     ((1UL<<12)|AVXFlag|OSXSAVEFlag)
#define CLMULFlag   ((1UL<< 1)|AVXFlag|OSXSAVEFlag)
#define VAESFlag    ((1UL<<25)|AVXFlag|OSXSAVEFlag)



inline bool SimdDetectFeature(U32 idFeature)
{
	int EAX, EBX, ECX, EDX;
	cpuid(0, EAX, EBX, ECX, EDX);
	if((ECX & idFeature) != idFeature)
		return false;
	return true;
}
[/cpp]