Re: [Xen-devel] [PATCH 07/18] mini-os: avoid crash if no console is provided

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-01-11 at 17:21 +0000, Daniel De Graaf wrote:

When/why does this happen? 

I guess it is because when starting the xenstore domain you cannot use
xenstore to communicate with xenconsoled (and/or it isn't even running
yet).

I wonder if there is a way we can do lazy-setup of the console for just
the xenstore domain?

Alternatively I seem to recall a little tool which Diego wrote to pull
the console ring out of a domain directly as a debuging aid but that
relies on us setting up a console ring and evtchn even if xenconsoled
cannot be involved which makes this patch unnecessary.

Ian.

> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
> ---
>  extras/mini-os/console/xencons_ring.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/extras/mini-os/console/xencons_ring.c 
> b/extras/mini-os/console/xencons_ring.c
> index 22fd618..14a8bd1 100644
> --- a/extras/mini-os/console/xencons_ring.c
> +++ b/extras/mini-os/console/xencons_ring.c
> @@ -25,7 +25,10 @@ static inline void notify_daemon(struct consfront_dev *dev)
>  
>  static inline struct xencons_interface *xencons_interface(void)
>  {
> -    return mfn_to_virt(start_info.console.domU.mfn);
> +    if (start_info.console.domU.evtchn)
> +        return mfn_to_virt(start_info.console.domU.mfn);
> +    else
> +        return NULL;
>  } 
>   
>  int xencons_ring_send_no_notify(struct consfront_dev *dev, const char *data, 
> unsigned len)
> @@ -38,6 +41,8 @@ int xencons_ring_send_no_notify(struct consfront_dev *dev, 
> const char *data, uns
>              intf = xencons_interface();
>          else
>              intf = dev->ring;
> +    if (!intf)
> +        return sent;
>  
>       cons = intf->out_cons;
>       prod = intf->out_prod;



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