Feeds

DragonFly BSD developer stung by Opteron bug

New 'Bulldozer' cores not affected

Top 5 reasons to deploy VMware with Tegile

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. ®

Intelligent flash storage arrays

More from The Register

next story
Netscape Navigator - the browser that started it all - turns 20
It was 20 years ago today, Marc Andreeesen taught the band to play
Sway: Microsoft's new Office app doesn't have an Undo function
Content aggregation, meet the workplace ... oh
Sign off my IT project or I’ll PHONE your MUM
Honestly, it’s a piece of piss
Return of the Jedi – Apache reclaims web server crown
.london, .hamburg and .公司 - that's .com in Chinese - storm the web server charts
NetWare sales revive in China thanks to that man Snowden
If it ain't Microsoft, it's in fashion behind the Great Firewall
Chrome 38's new HTML tag support makes fatties FIT and SKINNIER
First browser to protect networks' bandwith using official spec
Admins! Never mind POODLE, there're NEW OpenSSL bugs to splat
Four new patches for open-source crypto libraries
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
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?
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.