Print 64 comment(s) - last by clnee55.. on Dec 24 at 2:33 AM

Much of AMD's bad luck over the last three months revolves around a nasty bug it just can't shake

Erratum, to those in the hardware or software industry, is a nice way of saying "we missed a test case" during development and design. 

Yesterday, The Tech Report confirmed AMD's iteration of Intel's F00F bug.  The bug, which has been documented since at least early November, can cause a deadlock during recursive or nested cache writes. 

How does the TLB erratum occur?  All AMD quad-core processors utilize a shared L3 cache.  In instances where the software uses nested memory pages, this processor will experience a race condition. 

AMD's desktop product marketing manager Michael Saucier describes a race condition as a series of events "where the other guy wins who isn't supposed to win." 

In the software world, a typical memory race condition occurs when the memory arbiter is instructed to overwrite an older block of memory, but write the old block of memory to somewhere else in cache.  In the instance where two arbiters follow this same rule set, its easy to see how a race condition can occur: both arbiters attempt to overwrite the same blocks of information, resulting in a deadlock.

From what AMD engineers would tell DailyTech, this example is very similar to what occurs with nested memory pages in virtualized machines on these K10 processors. 

AMD has since released a new BIOS patch for all K10 motherboards, including the often cited but rarely seen MSI K9A2 Platinum.  This patch, confirmed by DailyTech, will result in at least a 10% reduction in general computing speed. 

AMD partners tell DailyTech that all bulk Barcelona shipments have been halted pending application screening based on the customer.  Cray, for example, was allowed its latest allocation for machines that will not use these nested virtualization techniques.  Other AMD corporate customers were told to use Revision F3 (K8) processors in the meantime. 

The TLB erratum will be fixed in the B3 stepping of all AMD quad-core processors, including Phenom and Barcelona.  However, AMD considers the B3 stepping a "March" item on its 2008 roadmap.  Processors shipped between then and now will still carry the TLB bug, though with the BIOS workaround these machines will not experience a lockup. 

The delayed Phenom 9700 is affected by the TLB bug, though AMD insiders tell DailyTech the upcoming 2.6 GHz Phenom 9900 is not affected.  This indicates Phenom 9900 will carry the B3-stepping designation.

AMD's latest roadmap hints that its tri-core processors are merely quad-core processors with one core disabled. The company also indicated that it will introduce some of these tri-core processors with the L3 cache disabled.  Removing the shared-L3 cache from the chip design eliminates the TLB bug.

In a likely-related event, AMD's newest corporate roadmap scheduled three Phenom processors for the first half of 2008; one of which is the Phenom 9700.  The company will launch eleven new 65nm K8 processors in the same time period.

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By MagnumMan on 12/5/2007 2:45:09 PM , Rating: 2
I think I should get a 10-20% refund from AMD on my Phenom 9500, for the 10-20% performance reduction this BIOS fix implements. That or offer to upgrade 9500s to something newer for early adopters when a fix comes out.

RE: 10-20%
By masher2 on 12/5/2007 2:55:42 PM , Rating: 2
Don't worry. I'm sure an attorney is already putting together details of a class action suit for everyone affected by the bug.

RE: 10-20%
By KristopherKubicki on 12/5/2007 4:18:11 PM , Rating: 2
Now it would be nice if they included journalists too so I could get the last 3 months of my life back ... :)

RE: 10-20%
By Clauzii on 12/5/2007 6:00:53 PM , Rating: 2
True, but in the court You'd probably only get 10-20% of that since that was the actual time lost!

Or You can sue them for all of it. Spending time writing articles about something buggy...

Nah, maybe not.

Btw.: How many Barcelona/Phenoms are already sold?

PS: Living in Denmark rocks (the 18x Opterons).
At the moment, Barcelona GOT rocks.

RE: 10-20%
By Ringold on 12/5/2007 8:14:31 PM , Rating: 2
I just did a quick & dirty estimation, and living in the US the difference in our marginal tax rates would allow me to buy, I think, about 30 extra Opterons, plugging in $200 each. There's some fudge there, but didn't count the VAT, don't know how you guys apply that.

America rocks. :P

RE: 10-20%
By Strunf on 12/5/2007 6:42:52 PM , Rating: 2
Yeah and they'll probably ask for a 10-20% of the AMD profits... and since they are negative it's actually the attorney that will pay AMD instead. That would be the a first on the never ending list of dumb class actions.

RE: 10-20%
By TomZ on 12/5/2007 3:15:00 PM , Rating: 1
They have stopped volume shipments of the processors, so I would guess that AMD sees this as a pretty serious issue. Therefore, I think it is reasonable to request/demand a replacement part when they finally ship them.

If AMD is proactive, they will offer this anyway, but I'd be surprised if they do.

RE: 10-20%
By GeorgeOrwell on 12/6/2007 7:02:37 AM , Rating: 1
If you use Firefox, it looks like you are in line for a 57% refund.

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