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Vol. 2A 3-417
INSTRUCTION SET REFERENCE, A-M
FXRSTOR—Restore x87 FPU, MMX , XMM, and MXCSR State
Virtual-8086 Mode Exceptions
Same exceptions as in real address mode.
#PF(fault-code) For a page fault.
#AC For unaligned memory reference.
#UD If the LOCK prefix is used.
Compatibility Mode Exceptions
Same exceptions as in protected mode.
64-Bit Mode Exceptions
#SS(0) If a memory address referencing the SS segment is in a non-
canonical form.
#GP(0) If the memory address is in a non-canonical form.
If memory operand is not aligned on a 16-byte boundary,
regardless of segment.
For an attempt to set reserved bits in MXCSR.
#MF If there is a pending x87 FPU exception.
#PF(fault-code) For a page fault.
#NM If CR0.TS[bit 3] = 1.
#UD If CR0.EM[bit 2] = 1.
If CPUID.01H:EDX.FXSR[bit 24] = 0.
If instruction is preceded by a LOCK prefix.
#AC If this exception is disabled a general protection exception
(#GP) is signaled if the memory operand is not aligned on a
16-byte boundary, as described above. If the alignment check
exception (#AC) is enabled (and the CPL is 3), signaling of #AC
is not guaranteed and may vary with implementation, as
follows. In all implementations where #AC is not signaled, a
general protection exception is signaled in its place. In addition,
the width of the alignment check may also vary with implemen-
tation. For instance, for a given implementation, an alignment
check exception might be signaled for a 2-byte misalignment,
whereas a general protection exception might be signaled for all
other misalignments (4-, 8-, or 16-byte misalignments).