Re: [gentoo-user] serial port identification question

[David Relson]

On Fri, 25 Dec 2009 16:56:00 -0600
Dale wrote:

...[snip]...

> Are you sure you enabled this in the kernel?  It is under   Device
> Drivers > Character devices > Serial Drivers then enable these:
>
> <*> 8250/16550 and compatible serial support
> (4) Maximum number of 8250/16550 serial ports
> (4) Number of 8250/16550 serial ports to register at runtime
>
> At least that works for my dial-up modem and my UPS.
>
> You may be able to put two instead of four but as I said, it works
> here like this.  I only have two ports tho.
>
> Dale
>
> :-)  :-)

Hello Dale,

My 32-bit gentoo system, which is the one in question, has the
following options set:

   #
   # Serial drivers
   # CONFIG_SERIAL_8250=m
   CONFIG_FIX_EARLYCON_MEM=y
   CONFIG_SERIAL_8250_PCI=m
   # CONFIG_SERIAL_8250_CS is not set
   CONFIG_SERIAL_8250_NR_UARTS=4
   CONFIG_SERIAL_8250_RUNTIME_UARTS=4
   # CONFIG_SERIAL_8250_EXTENDED is not set

This should be sufficient to create /dev/ttyS0 thru /dev/ttyS3, though
they are not created.

(In truth NR_UARTS=2 is the proper value.)

Using MAKEDEV, I can manually create ttyS0 thru ttyS3.  

Running "stty -f /dev/ttyS? -a" indicates that ttyS0 and ttyS1 are fine
while ttyS2 and ttyS3" gives:
                                                                                                                    
    stty: /dev/ttyS2: Input/output error
    stty: /dev/ttyS3: Input/output error

Regards,

David