Feeds

DragonFly BSD developer stung by Opteron bug

New 'Bulldozer' cores not affected

Top three mobile application threats

Matthew Dillon, the lead developer behind the DragonFly BSD fork of the open source FreeBSD Unix variant, had some issues with crashes on Opteron-based systems running his operating system for more than a year - and now Advanced Micro Devices says it's a bug in earlier generations of Opteron processors.

The errata does not affect current Opteron 4200 and 6200 processors or the impending Opteron 3200 chips, all of which have a different microarchitecture based on the "Bulldozer" cores.

Dillon described the crashes he was seeing with Dragonfly BSD in a posting on his kernel list on Christmas Day, and said he had been bug hunting for more than a year.

The problem occurs with the cc1 C compiler in the open-source GNU gcc 4.4.7 compiler set. Dillon ran tests on Opteron and Phenon II machines as well as on Sandy Bridge Xeon E3 processors from Intel, and said he didn't see the issue on Intel iron and had discounted the OS as the source of the problem causing the crashes. On Monday, in another post, Dillon said that after reviewing his issues, AMD confirmed the bug and said that doing certain kinds of loop operations, the processor can incorrectly update some Opteron stack pointers.

AMD provided El Reg with the following statement about the bug:

A program exception has been identified in previous generations of the AMD Opteron processor that occurs in certain environments that leverage a very specific GCC compiler build. A workaround has been identified for the small segment of customers this could potentially impact.

It's also important to note the following:

  • Only one external software developer has reported this observation.
  • This could only impact previous generation products (codenames: "Barcelona," "Shanghai," "Istanbul," "Lisbon," and "Magny-Cours").
  • While there are millions of these processors in the field, no other cases have been reported.
  • To see this observation multiple events needed to happen concurrently and required a certain BSD-derivative environment (BSD is based on the Unix operating system) that uses a unique GCC compiler build.
  • This erratum CANNOT occur on AMD Opteron 3200, 4200 and 6200 ("Valencia" and "Interlagos") Series processors since it utilizes a different microarchitecture.

And finally and even more important for readers to understand, AMD and Intel post errata updates on a regular basis, the difference here is a developer with a blog and unique GCC compiler build uncovered it.

In the wake of that statement, AMD told Dillon that it would be updating its revision guides for its 10h and 12h processors to document this erratum, which has been given issue #721. At that time, AMD will provide a model-specific workaround to the issue, it said. ®

Mobile application security vulnerability report

More from The Register

next story
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Captain Kirk sets phaser to SLAUGHTER after trying new Facebook app
William Shatner less-than-impressed by Zuck's celebrity-only app
Apple fanbois SCREAM as update BRICKS their Macbook Airs
Ragegasm spills over as firmware upgrade kills machines
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Put down that Oracle database patch: It could cost $23,000 per CPU
On-by-default INMEMORY tech a boon for developers ... as long as they can afford it
Google shows off new Chrome OS look
Athena springs full-grown from Chromium project's head
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.