Re: [Xen-tools] [PATCH] An example console driver using the store

[Anthony Liguori <aliguori@xxxxxxxxxx>]

Rusty Russell wrote:

> On Mon, 2005-08-08 at 12:37 -0500, Anthony Liguori wrote:
>  
>
> > Hi Rusty,
> >
> > One thing we might want to consider doing is having the domain builder 
> > allocate a page/event channel for the first console.
> >    
> Argh! I wrote this exactly to show that shoving more crap in the
> start_info struct was a bad idea!
>  
I figured you'd say that.  The console seems like a special case 
though.  I'm sort of on the fence about it.  What does everyone else think?
> > This gives us 
> > access to the console in a guest at start of day (and would work even if 
> > the store is not running).  I think this later reason is particuarily 
> > important since it's hard to debug the XenBus code in a guest without a 
> > console.
> >    
> There's still the hcall which prints out stuff, for emergency debugging.
> If the store daemon isn't up you should not be starting domUs: you'll
> have no devices and no console.
>  
The emergency console is meant for dom0.

Regards,

Anthony Liguori

> And even if the writes fail you can get the values out of the trace
> output of xenstored if you're in debugging mode.
>
>  
>
> > Also, it allows the PPC guys to hack up the hypervisor to support the 
> > PAPR console stuff since they can get to the ring buffer by examining 
> > the shared_info_frame.  It's not a long term solution but it's useful.
> >    
> They can also make their own ring buffer and publish it in the same way,
> surely?
>
> Rusty.
>  

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