[CentOS] How do I configure additional serial ports?

Alfred von Campe alfred at 110.net
Mon Mar 12 16:11:11 UTC 2007

On Mar 9, 2007, at 15:53, Matt Hyclak wrote:

> Have you looked at http://wiki.centos.org/HowTos/Custom_Kernel?

OK, I've rebuilt the kernel according to the instructions on this  
page (I ran into some issues; see earlier post in another thread).  I  
only changed two settings in the config file:

   CONFIG_SERIAL_8250_MANY_PORTS=y    [originally disabled]
   CONFIG_SERIAL_8250_NR_UARTS=20     [originally 4]

The good news is that the system now sees all eight serial ports  
(nine counting the one on the MB itself).  But the naming convention  
for the serial ports leaves something to be desired:

   # dmesg | fgrep tty
   ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
   ttyS14 at I/O 0x5020 (irq = 177) is a 16C950/954
   ttyS15 at I/O 0x5028 (irq = 177) is a 16C950/954
   ttyS44 at I/O 0x5030 (irq = 177) is a 16C950/954
   ttyS45 at I/O 0x5038 (irq = 177) is a 16C950/954
   ttyS46 at I/O 0x5060 (irq = 193) is a 16450
   ttyS47 at I/O 0x5068 (irq = 193) is a 16450
   ttyS48 at I/O 0x5070 (irq = 193) is a 16450
   ttyS49 at I/O 0x5078 (irq = 193) is a 16450
   ttyS50 at I/O 0x50a0 (irq = 217) is a 16C950/954
   ttyS51 at I/O 0x50a8 (irq = 217) is a 16C950/954
   ttyS52 at I/O 0x50b0 (irq = 217) is a 16C950/954
   ttyS53 at I/O 0x50b8 (irq = 217) is a 16C950/954
   ttyS54 at I/O 0x50e0 (irq = 225) is a 16450
   ttyS55 at I/O 0x50e8 (irq = 225) is a 16450
   ttyS56 at I/O 0x50f0 (irq = 225) is a 16450
   ttyS57 at I/O 0x50f8 (irq = 225) is a 16450

I haven't tested the ports yet, but it looks like they are now  
ttyS14, 15, 44, 45, 50, 51, 52, and 53.


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