Bulldozer Opterons L3 Cache

[Mixeur]

I'm currently testing some Bulldozer Opteron ES samples and I discovered that all cpus supposedly having 2x8MB are reported having 6MB by CPU-Z & 12MB by HWInfo.
I then checked my records I made on some serial models, and this is the same.
L3 cache is not reported at the level it should be.

Same with K10 Opterons. 2MB missing (6174 => 10MB instead of 12MB)

Any idea ?

[frag_]

I looked at 6174 cpuid dump and... probably AMD is at fault here +)
If you parse it according to AMD CPUID Specification, you will get that L3 size range (!) is between 10MB and 10.5MB.

[Mixeur]

So it would be "just" a CPUID Specification bug ?

Interesting that none reported it before. Some of those parts are 10 years old !

[frag_]

CPU reports wrong value or the Specification was not updated.
I found lots of 61xx results and all are with wrong 10MB size.

[Mixeur]

Yes. And all 62xx and all 63xx I tested so far as well.

[Neon]

Part of the discrepancy is that Windows does not see all of the L3 cache, which I wrote about here:
http://www.cpu-world.com/forum/viewtopic.php?p=222361#222361

[Mixeur]

perfect answer. Never seen that thread before

[frag_]

In theory you can get full L3 disabling "Probe Filter" (or "HT Assist") option in BIOS.
Can you try it?