Intel architecture ia-32 User Manual

1-8 Vol. 3A

An exception is an event that typically occurs when an instruction causes an error. For example,
an attempt to divide by zero generates an exception. However, some exceptions, such as break-
points, occur under other conditions. Some types of exceptions may provide error codes. An
error code reports additional information about the error. An example of the notation used to
show an exception and error code is shown below:

#PF(fault code)

This example refers to a page-fault exception under conditions where an error code naming a
type of fault is reported. Under some conditions, exceptions which produce error codes may not

Input value for EAX register

CPUID.01H:ECX.SSE [bit 25] = 1

Value (or range) of output

Output register and feature flag or field 

name with bit position(s)

CR4.OSFXSR[bit 9] = 1

Feature flag or field name 

with bit position(s)

Value (or range) of output

Example CR name

Feature flag or field name with bit position(s)

IA32_MISC_ENABLES.ENABLEFOPCODE[bit 2] = 1

Value (or range) of output

Example MSR name

OM17732