This section answers common questions about serial communications with FreeBSD. PPP is covered in the Networking section.
14.1. | Which multi-port serial cards are supported by FreeBSD? |
There is a list of these in the Serial Communications chapter of the handbook. Most multi-port PCI cards that are based on 16550 or clones are supported with no extra effort. Some unnamed clone cards have also been known to work, especially those that claim to be AST compatible. Check uart(4) and sio(4) to get more information on configuring such cards. | |
14.2. | How do I get the boot: prompt to show on the serial console? |
14.3. | 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 this command after your system is up and running: % dmesg | grep -E "^sio[0-9]" Here is some example output from the above command: sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
sio0: type 16550A
sio1: <16550A-compatible COM port> port 0x2f8-0x2ff irq 3 on acpi0
sio1: type 16550A This shows two serial ports. The first is on
IRQ 4, is using port address The | |
14.4. | How do I access the serial ports on FreeBSD? |
The third serial port, You use
| |
14.5. | How do I enable support for a multiport serial card? |
Again, the section on kernel configuration provides information about configuring your kernel. For a multiport serial card, place an sio(4) line for each serial port on the card in the device.hints(5) file. But place the IRQ specifiers on only one of the entries. All of the ports on the card should share one IRQ. For consistency, use the last serial port to specify the IRQ. Also, specify the following option in the kernel configuration file: options COM_MULTIPORT The following hint.sio.4.at="isa"
hint.sio.4.port="0x2a0"
hint.sio.4.flags="0x701"
hint.sio.5.at="isa"
hint.sio.5.port="0x2a8"
hint.sio.5.flags="0x701"
hint.sio.6.at="isa"
hint.sio.6.port="0x2b0"
hint.sio.6.flags="0x701"
hint.sio.7.at="isa"
hint.sio.7.port="0x2b8"
hint.sio.7.flags="0x701"
hint.sio.7.irq="12" The flags indicate that the master port has minor number
| |
14.6. | Can I set the default serial parameters for a port? |
See the Serial Communications section in the FreeBSD Handbook. | |
14.7. | How can I enable dialup logins on my modem? |
Please read the section about Dial-in Services in the FreeBSD Handbook. | |
14.8. | How can I connect a dumb terminal to my FreeBSD box? |
You can find this information in the Terminals section of the FreeBSD Handbook. | |
14.9. | Why can I not run |
On your system, the programs tip(1) and cu(1)
can only access the Alternatively, you can let everyone on your system run tip(1) and cu(1) by typing: # chmod 4511 /usr/bin/cu
# chmod 4511 /usr/bin/tip |
This, and other documents, can be downloaded from http://ftp.FreeBSD.org/pub/FreeBSD/doc/
For questions about FreeBSD, read the
documentation before
contacting <questions@FreeBSD.org>.
For questions about this documentation, e-mail <doc@FreeBSD.org>.