[CentOS] How do I configure additional serial ports?

Alfred von Campe alfred at 110.net
Fri Mar 9 20:40:52 UTC 2007

On Mar 9, 2007, at 14:42, Michael D. Kralka wrote:
> The OX16PCI954 chip from Oxford includes a PCI bridge (0a:0a.1 and
> 0a:0c.1 in your lspci list) that can be used to "glue" additional (non
> PCI-enabled) Quad-UARTs to the OX16CPI954.
> The standard Linux serial driver always detects 4 phantom ports on  
> this
> bridge; which explains why ttyS1-ttyS3 are detected as 16450 (Linux
> cannot detect what they are -- since they don't exist -- and  
> defaults to
> 16450s).
> When reconfiguring your kernel, you should take these 4 phantom ports
> (per card) into account (since they will consumed /dev/ttyS# device
> files). If you have two such cards, you should configure at lest 16
> non-legacy ports.

This is very interesting.  Thanks for posting that.  I was wondering  
what those ports were and why there were only three.  I think what's  
happening is that by default, only device nodes /dev/sttyS0-7 are  
created, and since there is one serial port on the motherboard  
(ttyS0), that only leaves room for 7 more: 3 phantom and 4 real (I'm  
just glad it's not the other way around).

Until I can get the kernel to rebuild (see my previous post), I can  
not test the theory that changing the kernel config file will make  
the other 4 ports available.


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