Intel IA-32 - Manual (Page 215)

Vol. 3A 5-39
INTERRUPT AND EXCEPTION HANDLING
Interrupt 9—Coprocessor Segment Overrun
Exception Class Abort. (Intel reserved; do not use. Recent IA-32 processors do not
generate this exception.)
Description
Indicates that an Intel386 CPU-based systems with an Intel 387 math coprocessor detected a
page or segment violation while transferring the middle portion of an Intel 387 math copro-
cessor operand. The P6 family, Pentium, and Intel486 processors do not generate this exception;
instead, this condition is detected with a general protection exception (#GP), interrupt 13.
Exception Error Code
None.
Saved Instruction Pointer
The saved contents of CS and EIP registers point to the instruction that generated the exception.
Program State Change
A program-state following a coprocessor segment-overrun exception is undefined. The program
or task cannot be resumed or restarted. The only available action of the exception handler is to
save the instruction pointer and reinitialize the x87 FPU using the FNINIT instruction.