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  • smidlaAugust 24, 2011 4:32 PM PDT   
    Detecting AVX
    Hi!

    I have a processor with the next brand string: "Intel(R) Core(TM) 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!

    Brijender Bharti August 24, 2011 4:49 PM PDT
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    		 #1
    Detecting AVX
    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

    smidlaAugust 24, 2011 5:16 PM PDT
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    		 #2 Reply To #1
    Detecting AVX
    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?

    Brijender Bharti August 24, 2011 5:41 PM PDT
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    		 #3 Reply To #2
    Detecting AVX
    Thats true. But you should have Win7 SP1 also. Win7 does not support AVX.

    Igor LevickiOctober 9, 2011 6:56 AM PDT
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    		 #4
    Detecting AVX
    That CPU does not support AVX, just AES.
    http://ark.intel.com/products/43560


    --
    Regards,
    Igor Levicki

    If you find my post helpfull, please rate it and/or select it as a best answer where applies. Thank you.

    Pourya_ShirazianOctober 26, 2011 10:58 AM PDT
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    		 #5 Reply To #4
    Detecting AVX
    You can use this C code to detect AVX and other features on the processor:

    #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;
}


    Pourya Shirazian

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