Specifications

Product Errata 97
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
25759 Rev. 3.79 July 2009
352 SYSCALL Instruction May Execute Incorrectly Due to
Breakpoint
Description
A SYSCALL 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 SYSCALL instruction.
• The processor is in 64-bit mode or compatibility mode.
• The instruction would not generate any other exception.
• SYSCALL Flag Mask Register[16] (MSRC000_0084[16]) is set to 1b.
• RFLAGS.RF is set to 1b.
Potential Effect on System
None expected during normal operation. Kernel debuggers may observe unpredictable system
behavior.
Suggested Workaround
Operating system software should clear SYSCALL Flag Mask Register[16] (MSRC000_0084[16]) to
0b during initialization.
Fix Planned
No