Feeds

'Super-secret' debugger discovered in AMD CPUs

Password-protected feature goes beyond x86

Top 5 reasons to deploy VMware with Tegile

A hardware hacker has discovered a secret debugging feature hidden in all AMD chips made in the past decade.

The password-protected debugger came as a shock to reverse-engineers who have hungered for an on-chip mechanism for performing conditional and direct-hardware breakpoint operations. Although AMD has built the firmware-controlled feature into all chips since the Athlon XP, the company kept it a closely guarded secret that was only disclosed late last week by a hacker who goes by the name Czernobyl.

“AMD processors (Athlon XP and better) have included firmware-based debugging features that expand greatly over standard, architecturally defined capabilities of x86,” the hacker wrote. “For some reason, though, AMD has been tightly secretive about these features; hint of their existence was gained by glancing at CBID's page.”

To put a chip into developer mode, a user must first enter what amounts to a password — 9C5A203A — into the CPU's EDI register. Czernobyl was able to deduce the secret setting by brute forcing the key.

Presumably, the debugger is an internal AMD utility used during development and then turned off before shipping. Its discovery by world + dog means that everyday users may have powerful new tools to hack, debug, and reverse-engineer their hardware. Now that its existence and the instructions for turning it on are known, the real discoveries about exactly what can be done with it are sure to commence. ®

Top 5 reasons to deploy VMware with Tegile

More from The Register

next story
Oi, Tim Cook. Apple Watch. I DARE you to tell me, IN PERSON, that it's secure
State attorney demands Apple CEO bows the knee to him
Phones 4u website DIES as wounded mobe retailer struggles to stay above water
Founder blames 'ruthless network partners' for implosion
Will BlackBerry make a comeback with its SQUARE smartphones?
Plus PC PIMs from company formerly known as RIM
Apple's iPhone 6 first-day sales are MEANINGLESS, mutters analyst
Big weekend queues only represent fruity firm's supply
Hey, Mac fanbois. HGST wants you drooling over its HUGE desktop RACK
What vast digital media repository could possibly need 64 TERABYTES?
Soundbites: News in brief from the Wi-Fi audiophile files
DTS and Sonos sing out but not off the same hymnsheet
prev story

Whitepapers

Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Beginner's guide to SSL certificates
De-mystify the technology involved and give you the information you need to make the best decision when considering your online security options.