11.1. How do I tell if FreeBSD found my serial ports or modem cards?

As the FreeBSD kernel boots, it will probe for the serial ports in your system for which the kernel was configured. You can either watch your system closely for the messages it prints or run the command

            dmesg | grep sio
          

Here's some example output from the above command:

            sio0 at 0x3f8-0x3ff irq 4 on isa
            sio0: type 16550A
            sio1 at 0x2f8-0x2ff irq 3 on isa
            sio1: type 16550A
          

This shows two serial ports. The first is on irq 4, is using port address 0x3f8, and has a 16550A-type UART chip. The second uses the same kind of chip but is on irq 3 and is at port address 0x2f8. Internal modem cards are treated just like serial ports---except that they always have a modem ``attached'' to the port.

The GENERIC kernel includes support for two serial ports using the same irq and port address settings in the above example. If these settings aren't right for your system, or if you've added modem cards or have more serial ports than your kernel is configured for, just reconfigure your kernel. See section about building a kernel for more details.