Re: [Xen-devel] [PATCH] xend: notify xenpv device model that console info is ready

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Feb 23, 2010 at 04:03:48PM +0900, Kouya Shimura wrote:
Content-Description: message body text
> Sometimes PV domain with vfb doesn't boot up. /sbin/kudzu is stuck.
> After investigation, I've found that the evtchn for console is not
> bound at all.
> 
> Normal sequence of evtchn initialization in qemu-dm for xenpv is:
> 1) watch xenstore backpath (/local/domain/0/backend/console/<domid>/0)
> 2) read console info (/local/domain/<domid>/console/{type, ring-ref, port..})
> 3) bind the evtchn to the port.
> 
> But in some case, xend writes to the backpath before the console info

Would it be better to fix the race condition?

> is prepared, and never write to the backpath again. So the qemu-dm fails
> at 2) and never reach to 3).
> 
> When this happens, manually xenstore-write command on Domain-0
> resumes the guest.
> 
> Signed-off-by: Kouya Shimura <kouya@xxxxxxxxxxxxxx>
> 

> diff -r 4ba4323889b9 tools/python/xen/xend/XendDomainInfo.py
> --- a/tools/python/xen/xend/XendDomainInfo.py Mon Feb 22 18:47:22 2010 +0000
> +++ b/tools/python/xen/xend/XendDomainInfo.py Tue Feb 23 14:50:40 2010 +0900
> @@ -1642,6 +1642,11 @@ class XendDomainInfo:
>                  console_uuid = serial_consoles[0].get('uuid')
>                  self.info.console_update(console_uuid, 'location',
>                                           self.console_port)
> +                # Notify xenpv device model that console info is ready
> +                if not self.info.is_hvm() and self.info.has_rfb():
> +                    console_ctrl = self.getDeviceController('console')
> +                    # The value is unchanged. Just for xenstore watcher
> +                    console_ctrl.writeBackend(0, 'uuid', console_uuid)
>                  
>  
>          # Update VNC port if it exists and write to xenstore

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