Problems with console io from a PV guest

Problems with console io from a PV guest

[Simon Martin]

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Hi All,

I am using the latest and greatest 4.4 unstable and I'm having problems 
with console IO. I've been playing around with it for the last couple of 
days and I can't seem to find what's wrong. I start the guest with the 
"xl create -c" command and I only get one line of output. Input works 
fine.

My code is based on the mini-os implementation. My sequence of events is 
as follows from startup is as follows:

1.- Map in the shared_info page

2.- Initialise the console event

3.- Write a line to the console. Send the console channel event. This 
seems to work as I see the output in the console and the console cons 
and prod indices are equal on the next write call.

4.- After writing I get an event on the console channel with no 
characters.

5.- Any writes after this are not shown on the console.

Any idea what I'm doing wrong?

Regards.


--
  _     _  Debian GNU User   Simon Martin
| |   (_)_ __  _   ___  __  Project Manager
| |   | | '_ \| | | \ \/ /  Milliways
| |___| | | | | |_| |>  <   mailto: smartin@milliways.cl
|_____|_|_| |_|\__,_/_/\_\
Si Hoc Legere Scis Nimium Eruditionis Habes

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Re: Problems with console io from a PV guest

[Andrew Cooper]

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On 30/10/13 21:17, Simon Martin wrote:
> Hi All,
>  
> I am using the latest and greatest 4.4 unstable and I'm having
> problems with console IO. I've been playing around with it for the
> last couple of days and I can't seem to find what's wrong. I start the
> guest with the "xl create -c" command and I only get one line of
> output. Input works fine.
>  
> My code is based on the mini-os implementation. My sequence of events
> is as follows from startup is as follows:
>  
> 1.- Map in the shared_info page
>  
> 2.- Initialise the console event
>  
> 3.- Write a line to the console. Send the console channel event. This
> seems to work as I see the output in the console and the console cons
> and prod indices are equal on the next write call.
>  
> 4.- After writing I get an event on the console channel with no
> characters.

Do you mean that you get an event on the event channel but there is no
movement on the prod/cons indicies?

~Andrew

>  
> 5.- Any writes after this are not shown on the console.
>  
> Any idea what I'm doing wrong?
>  
> Regards.
>  
>  
> --
>  _     _  Debian GNU User   Simon Martin
> | |   (_)_ __  _   ___  __  Project Manager
> | |   | | '_ \| | | \ \/ /  Milliways
> | |___| | | | | |_| |>  <   mailto: smartin@milliways.cl
> |_____|_|_| |_|\__,_/_/\_\
> Si Hoc Legere Scis Nimium Eruditionis Habes
>  
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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Re: Problems with console io from a PV guest

[Simon Martin]

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>>4.- After writing I get an event on the console channel with no 
>>characters.
>
>Do you mean that you get an event on the event channel but there is no 
>movement on the prod/cons indicies?
>
>~Andrew


Yes. The prod/cons indices are identical.

Simon

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