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C28111

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warning C28111: The IRQL where the floating-point state was saved does not match the current IRQL (for this restore operation).

Additional information

The floating Save/Restore functions require that the IRQL be the same at the time of save and the corresponding restore.

The IRQL at which the driver is executing when it restores a floating-point state is different than the IRQL at which it was executing when it saved the floating-point state.

Because the IRQL at which the driver runs determines how the floating-point state is saved, the driver must be executing at the same IRQL when it calls the functions to save and to restore the floating-point state.

Example

The following code example elicits this warning.

void driver_utility()
{
    // running at APC level
    KFLOATING_SAVE FloatBuf;
    if (KeSaveFloatingPointState(&FloatBuf))
    {
        KeLowerIrql(PASSIVE_LEVEL);
        ...
        KeRestoreFloatingPointState(&FloatBuf);
    }
}

The following code example avoids this warning.

void driver_utility()
{
    // running at APC level
    KFLOATING_SAVE FloatBuf;
    if (KeSaveFloatingPointState(&FloatBuf))
    {
        KeLowerIrql(PASSIVE_LEVEL);
        ...
        KeRaiseIrql(APC_LEVEL, &old);
        KeRestoreFloatingPointState(&FloatBuf);
    }
}