Re: [Xen-users] Export /dev/lp0 as VBD?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> My Xen 3.0.3 server has a printer attached on the printer port /dev/lp0.
> I would like to set up a domU printserver. Can I treat /dev/lp0 as a
> block device and give a domU access to it simply by adding something
> like this to the domU's configuration:
>
>  'phy:lp0,lp0,w'

I'm afraid not, printers appear as character devices and there's not a generic 
way of passing them through.

> If not, is there another way of letting domU use the printer, short of
> getting an lpt->usb convertor

That wouldn't be very helpful if your domU is PV since it's not possible to 
pass through USB to PV guests.  There is passthrough for FV guests, but I've 
heard some dubious accounts of its stability - I'm not sure if it's an 
officially supported option...

> or installing a PCI card with an lpt port? 

That would work (although it would imply giving the guest more permissions in 
order to let it own the PCI device) for a PV domU.

> I really don't like setting up dom0 as a printserver.

That's sensible, although I sometimes suggest this sort of thing because it 
makes life easier (depending on your deployment).

One thing you might be able to do is just give the domain access to the IO 
ports for the parallel port (and interrupts if there are any...  I don't know 
much about the parallel port hardware).  You could then have the guest drive 
the printer directly through it; this might work, although it may be 
necessary to make sure dom0 doesn't try to do anything with the port...

Hope this helps,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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