Potential Dragonfly Issue with some older AMD processors

Solution Verified - Updated -


Servers utilizing AMD family 10h processors running Red Hat Enterprise
Linux version 5 or version 6 in 64-bit mode. The related processors are:

  • AMD Opteron(tm) 1300 Series Processor (Budapest, Suzuka)
  • AMD Opteron 2300 Series Processor (Barcelona, Shanghai)
  • AMD Opteron 8400 Series Processor (Barcelona, Shanghai)
  • AMD Opteron 2400 Series Processor (Istanbul)
  • AMD Opteron 8400 Series Processor (Istanbul)
  • AMD Opteron 4100 Series Processor (Lisbon)
  • AMD Opteron 6100 Series Processor (Magny-Cours)

For additional information, see:
- The family 10h revision guide
- AMD erratum #721 in the following AMD documents: Revision Guide for
- AMD Family 10h Processors, order #41322
Both are at



Possible problem known as the "dragonfly issue" with some older AMD processors:



AMD has informed Red Hat that any customers wishing to disable the stack engine offset feature for the specific families and architecture affected to eliminate any possibility of this issue should contact their AMD representative. If they do not know or have an AMD representative, they could contact eric.morton@amd.com.

Note that disabling the stack engine may affect performance. Benchmarks observed the impact was a 1.6% performance hit that would only impact the affected CPUs and all existing code would be immediately fixed.

Root Cause

AMD and Red Hat have researched this issue at length. While we have not seen this problem in our internal testing or reported by any of our customers, our joint analysis shows that there is a small risk that the stack pointer may be incorrectly updated after a highly specific and uncommon sequence of instructions is executed as part of a recursive call or return. We have not been able to recreate the bug.

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