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INVD            Invalidate Internal Caches           Flags: Not altered

INVD                                                 CPU: 486+ Priv

    Invalidates (flushes) the processor's internal caches and issues a
    special-function 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.


    Note
    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. This instruction is also
    implementation-dependent; its function may be implemented
    differently on future Intel Architecture processors.

    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.


    Opcode      Format
    0F 08       INVD


    Length and timing
    Operands    Bytes   8088    186     286     386     486     Pentium
    -             2     -       -       -       -       ??     ??    NP