Specifications

98 Product Errata
25759 Rev. 3.79 July 2009
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
353 SYSRET Instruction May Execute Incorrectly Due to
Breakpoint
Description
A SYSRET instruction will execute incorrectly and an incorrect debug exception will be taken when
all of the following conditions are satisfied:
• An enabled instruction breakpoint address matches the RIP of the SYSRET instruction.
• The processor is in 64-bit mode or compatibility mode.
• The instruction would not generate any other exception.
• R11[16] is cleared to 0b.
• RFLAGS.RF is set to 1b.
Potential Effect on System
None expected during normal operation. Kernel debuggers may observe unpredictable system
behavior.
Suggested Workaround
Software should set R11[16] to 1b before executing the SYSRET instruction in 64-bit mode.
Fix Planned
No