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Re: [Xen-devel] serial ports in a pv domU

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 03/19/2010 01:29:22 PM:

> On Fri, 2010-03-19 at 17:21 +0000, Michael D Labriola wrote:
> > Is there a way to pass a system's on-board serial port(s) into a 
> > paravirtualized domU?
> I think you can pass individual IO ports and interrupt through to a PV
> guest without necessarily passing through a PCI device. 
> I'm afraid I don't actually know the exact runes to cause xend or xl or
> whatever to do this though -- I think perhaps for xend lines like:
>    ioport=03f8-03f9
>    irq=3
> (or whatever the com port uses) in your config file might do the trick.
> > I don't have any on hand to test with, but would passing a PCI serial 
> > into the domU have any issues?
> I'd expect that to work alright.

Hmm, thought I had this working.  With 'ioports = ['3f8-3ff']' and 
'irq=[4]' in my cfg file, I get appropriate messages in domU's dmesg about 
initializing ttyS0...  But the device doesn't seem to work.  And the 
device still works in dom0...

I looked at the old InstallationNotes Wiki (last touched Nov 2007?) which 
says to blacklist the 8250, 8250_pnp, and serial_core modules... is this 
still needed with the pv_ops kernels?  Pretty sure I've got the serial 
stuff compiled into the kernel, so I can't really blacklist those unless I 
recompile.  I tried unbinding the devices from their driver via sysfs, but 
then the devices don't show up in domU at all...

Michael D Labriola
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