public static TimeVal GetBoottime()
    {
        var pLen = Marshal.AllocHGlobal(sizeof(int));
        sysctlbyname("kern.boottime", IntPtr.Zero, pLen, IntPtr.Zero, 0);
        var length = Marshal.ReadInt32(pLen);
        var pStr = Marshal.AllocHGlobal(length);
        sysctlbyname("kern.boottime", pStr, pLen, IntPtr.Zero, 0);
        return Marshal.PtrToStructure<TimeVal>(pStr);
    }