3-318
INSTRUCTION SET REFERENCE
INVDInvalidate Internal Caches
Description
This instruction invalidates (flushes) the processors internal caches and issues a special-func-
tion bus cycle that directs external caches to also flush themselves. Data held in internal caches
is not written back to main memory.
After executing this instruction, the processor does not wait for the external caches to complete
their flushing operation before proceeding with instruction execution. It is the responsibility of
hardware to respond to the cache flush signal.
The INVD instruction is a privileged instruction. When the processor is running in protected
mode, the CPL of a program or procedure must be 0 to execute this instruction.
Use this instruction with care. Data cached internally and not written back to main memory will
be lost. Unless there is a specific requirement or benefit to flushing caches without writing back
modified cache lines (for example, testing or fault recovery where cache coherency with main
memory is not a concern), software should use the WBINVD instruction.
Intel Architecture Compatibility
The INVD instruction is implementation dependent, and its function may be implemented
differently on future Intel Architecture processors. This instruction is not supported on Intel
Architecture processors earlier than the Intel486 processor.
Operation
Flush(InternalCaches);
SignalFlush(ExternalCaches);
Continue (* Continue execution);
Flags Affected
None.
Protected Mode Exceptions
#GP(0)
If the current privilege level is not 0.
Opcode
Instruction
Description
0F 08
INVD
Flush internal caches; initiate flushing of external caches.
