Feeds

AMD Opteron CPUs hit by heat stroke

'Marginal' effect, chip maker claims

Top three mobile application threats

Exclusive AMD today admitted it has inadvertently allowed a number of 2.6GHz and 2.8GHz single-core Opteron x52 and x54 processors that could corrupt data under extreme conditions to escape into the wild.

It is believed that the glitch is triggered when the affected chip's FPU is made to loop through a series of memory-fetch, multiplication and addition operations without any condition checks on the result of the calculations. The loop has to run over and over again for long enough to cause localised heating which together with high ambient temperatures could combine to cause the result of the operation to be recorded incorrectly, leading to data corruption.

To trigger the effect, the loop has to be run millions of time, an AMD customer source told Reg Hardware, potentially for hours at a time with no other operations being introduced during the run.

According to the source - who claimed to be party to emails highlighting the issue and sent by AMD to a number of the chip maker's major customers and partners - AMD has investigated the problem and found it was only able to reproduce the bug's effects in a synthetic benchmark test.

The problem is believed to affect only a fraction - perhaps no more than 3,000 individual CPUs - which managed to slip through AMD's screening net. It is not known how this so-called 'test escape' ocurred, but it took place "in part of 2005 and early 2006", an AMD spokesman said.

AMD said it has introduced another screening test to catch any further affected parts. Chips caught in this test in future will be re-rated at a lower clock speed to prevent the problem. The company is also working with OEMs to identify affected parts and contact customers who could be affected - if they are, they will be offered free replacements.

AMD stressed the problem was due to "a convergence of three specific simultaneous conditions", not a fault with the Opteron architecture. The company claimed the issue had not been observed on systems running commercially available applications.

"It's very hard to imagine this type of [tight FP loop] code in our [financial services] environment," Reg Hardware's source said. "The only thing I could think that would be coded this way would be some type of strange cipher code. For example, any type of 'for' loop that uses a compare operation would not have the problem." ®

Combat fraud and increase customer satisfaction

More from The Register

next story
Samsung Galaxy S5 fingerprint scanner hacked in just 4 DAYS
Sammy's newbie cooked slower than iPhone, also costs more to build
Leaked pics show EMBIGGENED iPhone 6 screen
Fat-fingered fanbois rejoice over Chinternet snaps
Microsoft lobs pre-release Windows Phone 8.1 at devs who dare
App makers can load it before anyone else, but if they do they're stuck with it
Report: Apple seeking to raise iPhone 6 price by a HUNDRED BUCKS
'Well, that 5c experiment didn't go so well – let's try the other direction'
Feast your PUNY eyes on highest resolution phone display EVER
Too much pixel dust for your strained eyeballs to handle
US mobile firms cave on kill switch, agree to install anti-theft code
Slow and kludgy rollout will protect corporate profits
Rounded corners? Pah! Amazon's '3D phone has eye-tracking tech'
Now THAT'S what we call a proper new feature
Oh no, Joe: WinPhone users already griping over 8.1 mega-update
Hang on. Which bit of Developer Preview don't you understand?
Zucker punched: Google gobbles Facebook-wooed Titan Aerospace
Up, up and away in my beautiful balloon flying broadband-bot
Sony battery recall as VAIO goes out with a bang, not a whimper
The perils of having Panasonic as a partner
prev story

Whitepapers

Designing a defence for mobile apps
In this whitepaper learn the various considerations for defending mobile applications; from the mobile application architecture itself to the myriad testing technologies needed to properly assess mobile applications risk.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.