[CentOS-virt] working config for xen which would transfer a serial interface

[Manuel Wolfshant]

  On 08/06/2010 04:24 PM, Philippe Naudin wrote:
>
> Are you sure your expansion board is based on the "classical" UART
> (8250 or 16550) ? Many add-on cards require specific modules.
>
Let's say I am 99% sure. It behaves exactly as a 16550, is listed in 
dmesg as
         0000:03:05.0: ttyS0 at I/O 0xec00 (irq = 21) is a 16550A
         0000:03:05.0: ttyS1 at I/O 0xe880 (irq = 21) is a 16550A
  and it works perfectly from Dom0. The only problem I face is 
transferring it to DomU.

> This will not work on dom0 if the serial port is already shared, but
> you can try it when no domU is running :
>
> $ for x in 0 1 2 3 4 ; do setserial /dev/ttyS$x ; done
> /dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
> /dev/ttyS1, UART: unknown, Port: 0x02f8, IRQ: 3
> /dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4
> /dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3
> /dev/ttyS4: No such file or directory
I did not mention in the first message, but both serial interfaces from 
the card are perfectly usable from Dom0, from a standard kernel and from 
Windows ( the computer was previously used to monitor some industrial 
equipments, without adding any special drivers).

[root at Dom0 ~]# for x in 0 1 2 3 4 ; do setserial /dev/ttyS$x ; done
/dev/ttyS0, UART: 16550A, Port: 0xec00, IRQ: 21
/dev/ttyS1, UART: 16550A, Port: 0xe880, IRQ: 21
/dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4
/dev/ttyS3, UART: unknown, Port: 0x02e8, IRQ: 3
/dev/ttyS4: No such file or directory


     What I am not 100% sure is that we correctly blacklist all the 
modules related to serial interfaces in Dom0. But OTOH exactly the same 
config ( modulo ports / irq ) works with the onboard interface.


     manuel