Ivy Bridge i5-3570K without rdrand

[Mario Andretti]

Installed i5-3570K into GA-Z68MA-D2H-B3 mobo. I am not getting the
RDRAND feature!

The rdrand instruction results in "illegal opcode".

Looking at the feature vector of the cpuid instruction reveals rdrand as
absent.

$ cpuid
eax in eax ebx ecx edx
00000000 0000000d 756e6547 6c65746e 49656e69
00000001 000306a9 06100800 3f9ae3bf bfebfbff
^

Bit 30 (counting from zero) of ecx will indicate presence of rdrand
according to http://www.intel.com/Assets/PDF/appnote/241618.pdf.

Any ideas?
- Bad processor with disabled execution unit
- Bad microcode from mobo
- This particular processor does not have it?

[VanguardLH]

Mario Andretti wrote:

> Installed i5-3570K into GA-Z68MA-D2H-B3 mobo. I am not getting the
> RDRAND feature! The rdrand instruction results in "illegal opcode".
> Looking at the feature vector of the cpuid instruction reveals rdrand
> as absent.
>

> Bit 30 (counting from zero) of ecx will indicate presence of rdrand
> according to http://www.intel.com/Assets/PDF/appnote/241618.pdf.

http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/3rd-gen-core-desktop-specification-update.pdf
Errata (sheet 3 of 4), page 11
Number 54

The comment field is supposed to be clickable but didn't work for me, so
jump to page 31 for the "BV54" section.

No, I don't do assembly coding on IA-86/64 architecture nor do I have
this processor and mobo setup. I just Google around and hope the above
article addresses your concern. Yeah, I know your reaction will likely
be "farking Intel, farking Gigabyte, won't work together, I'm screwed".

[Mario Andretti]

Am 17.06.2012 19:14, schrieb VanguardLH:

> http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/3rd-gen-core-desktop-specification-update.pdf
> Errata (sheet 3 of 4), page 11
> Number 54

This points to a processor erratum fixable by a BIOS workaround.
I have looked at Gigabyte, and, although not clearly visible, they do
have a fresher BIOS.
I was running f10c since about February, now they call it (just) f10.

This indeed fixed the problem!

Thanks for your help.

[Bill Davidsen]

VanguardLH wrote:
> Mario Andretti wrote:
>
>> Installed i5-3570K into GA-Z68MA-D2H-B3 mobo. I am not getting the
>> RDRAND feature! The rdrand instruction results in "illegal opcode".
>> Looking at the feature vector of the cpuid instruction reveals rdrand
>> as absent.
>>
>> Bit 30 (counting from zero) of ecx will indicate presence of rdrand
>> according to http://www.intel.com/Assets/PDF/appnote/241618.pdf.
>
> http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/3rd-gen-core-desktop-specification-update.pdf
> Errata (sheet 3 of 4), page 11
> Number 54
>
> The comment field is supposed to be clickable but didn't work for me, so
> jump to page 31 for the "BV54" section.
>

Good catch, a fixable issue.