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

[Rusty Russell <rusty@xxxxxxxxxxxxxxx>]

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!

> 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.

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.
-- 
A bad analogy is like a leaky screwdriver -- Richard Braakman


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