[et-mgmt-tools] -parallel supported?

Cole Robinson crobinso at redhat.com
Wed Sep 24 20:11:56 UTC 2008


Bob Tennent wrote:
>  >|>  >|>  I added
>  >|>  >|>
>  >|>  >|>     <parallel type='pty'>
>  >|>  >|>       <source path='/dev/lp0' />
>  >|>  >|>       <target port='0'/>
>  >|>  >|>     </parallel>
>  >|>  >|>
>  >|>  >|> to the <devices> section of the relevant file in
>  >|/etc/libvirt/qemu. The
>  >|>  >|> parallel "hardware" shows up in virt-manager, but with - as
>  >|the source
>  >|>  >|> path; running the domain yields
>  >|>  >|
>  >|>  >|>   libvirtError: internal error Timed out while reading console
>  >|startup
>  >|>  >|>   output
>  >|>  >|>
>  >|>  >|> Same result if I use <source path='/dev/pts/2' />. If I remove the
>  >|>  >|> parallel "hardware" in the virt-manager, the guest starts up OK.
>  >|>  >|
>  >|>  >|Your XML syntax is wrong. You specified a 'pty' but then gave it a
>  >|>  >|real path which doesn't make sense. You want type='dev' instead,
>  >|>  >|and the <target> element is redundant - that's an output only
>  >|>  >|element at this time. So, eg
>  >|>  >|
>  >|>  >|     <parallel type='dev'>
>  >|>  >|       <source path='/dev/lp0' />
>  >|>  >|     </parallel>
>  >|>  >|
>  >|>
>  >|> The example syntax at the libvirt.org site I was directed to is
>  >|>
>  >|>         <parallel type='pty'>
>  >|>           <source path='/dev/pts/2'/>
>  >|>           <target port='0'/>
>  >|>         </parallel>
>  >|>
>  >|> so that should be corrected if it's "wrong".
>  >|>
>  >|
>  >|The docs clearly explain that type='pty' is for redirection
>  >|to a psuedo tty, and type='dev' is for redirection to a
>  >|physical device. So in that respect, the docs are not
>  >|"wrong".
> 
> I'd be grateful if you could point me to that documentation. I can't
> find any reference to the difference between type 'dev' and type 'pty'
> at the libvirt.org site.
> 

>From the original link I posted:

http://libvirt.org/formatdomain.html#elementsConsole

Scroll down and it enumerates all the different serial/parallel/
console types (starting with 'Domain Logfile'). Fifth one listed
is 'Psuedo TTY', the type demonstrated in the syntax example. The
one following that is 'Host device proxy', which was the type you
are looking for.

> In any case, crashing on an incorrect type argument suggests a

Well, nothing should be crashing :) What version of libvirt are
you using? I'll try to reproduce.
 
>  >|That quoted piece is just the example of the general syntax.
>  >|It is not clearly labeled as such, but probably should be.
> 
> Your colleague suggested the example "didn't make sense." Whatever
> "general syntax" might be, shouldn't the example make sense?
> 

That given example does make sense, just not for your intended
case of redirecting parallel output to a physical host device.

- Cole




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