# Triggering Special Instructions

There are special instructions in x86 and AMD64 processors that might be configured to cause vm-exits when executed; thus, we can intercept them.

For example, we might be interested in the execution of I/O instructions (IN & OUT). We can monitor memory-mapped I/O using the [!monitor](https://docs.hyperdbg.org/commands/extension-commands/monitor) command, but for I/O mapped devices, we can use [!ioin](https://docs.hyperdbg.org/commands/extension-commands/ioin) and [!ioout](https://docs.hyperdbg.org/commands/extension-commands/ioout) commands.

{% hint style="danger" %}
Do not try to monitor all I/O ports or the I/O port for the serial device connected to the debugger if you are operating on **Debugger Mode**.
{% endhint %}

Using these commands, we can monitor I/O ports. For examples, let say we want to monitor the I/O port `0x3f8` for `IN`instruction.

```c
HyperDbg> !ioin 0x3f8
```

If we want to monitor port `0x3f8` for `OUT` instruction, we use the following command.

```c
HyperDbg> !ioout 0x3f8
```

Let's intercept another instruction.

We know that **CPUID** is an important instruction that tries to get processor features to see if a processor supports a special feature or not.

For example, we want to intercept all the CPUIDs that a process with process ID **0x490** tries to execute.

```c
HyperDbg> !cpuid pid 490
```

You can also break on the execution of other instructions like:

* **RDTSC** and **RDTSCP** using [!tsc](https://docs.hyperdbg.org/commands/extension-commands/tsc) command
* **RDPMC** using [!pmc](https://docs.hyperdbg.org/commands/extension-commands/pmc) command
* **VMCALL**s using [!vmcall](https://docs.hyperdbg.org/commands/extension-commands/vmcall) command


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