[Fedora-xen] ups connected to serial port, but can't communicate via ttyS0

[Richard W.M. Jones]

Kanwar Ranbir Sandhu wrote:
> On Mon, 2007-07-09 at 13:56 +0100, Richard W.M. Jones wrote:
>> Try the suggestions here:
>>
>> http://phaq.phunsites.net/2007/06/30/xen-console-grabbded-devttys0/
>>
>> In particular try booting with xencons=off (on the kernel command line, 
>> not the Xen hypervisor command line).
> 
> That worked!  My Smart UPS 1400 is now being monitored/controlled from
> dom0 with apcupsd.
> 
> There were some errors in /var/log/messages, though:
> 
> Jul  9 12:50:45 xenmaster kernel: serial8250: ttyS0 at I/O 0x3f8 (irq =
> 4) is a 16550A
> Jul  9 12:50:45 xenmaster kernel: 00:06: ttyS0 at I/O 0x3f8 (irq = 4) is
> a 16550A
> Jul  9 12:55:02 xenmaster kernel: Kernel command line: ro
> root=/dev/vg00/root xencons=tty1
> Jul  9 12:55:11 xenmaster kernel: WARNING: Failed to register Xen
> virtual console driver as 'tty1'
> Jul  9 12:55:14 xenmaster kernel: serial8250: ttyS0 at I/O 0x3f8 (irq =
> 4) is a 16550A
> Jul  9 12:55:14 xenmaster kernel: 00:06: ttyS0 at I/O 0x3f8 (irq = 4) is
> a 16550A
> 
> I'll try with a different tty later, say tty6.  But, I don't know if
> that will fix the above warning.

It's absolutely ages since I used serial ports under Linux -- I mean 10 
years at least -- but my recollection is that they are called things 
like ttyS1 (with the 'S' in there).

> I have another question: can I hand the serial port to a domU, or does
> it have to be present in dom0?

There's a bit about this on the Xen wiki:

http://wiki.xensource.com/xenwiki/InstallationNotes#head-327388b324997719e864f8740fed06036c799e38

Rich.

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