Re: bug in usbback

[Noboru Iwamatsu <n_iwamatsu@jp.fujitsu.com>]

Hi,

James Harper wrote:
> Also, a question on behaviour:
> 
> When we receive a reconfigure event, I assume that we should then read
> 'num-ports' and scan through each of the port-n values in xenstore. Is
> there any guarantee that a device hasn't been unplugged and replugged
> from the same port during the reconfiguration window? How should I
> detect such a thing if the value of port-n hasn't changed? Should I then
> probe each device? I'm doing this under Windows which is a bit more
> picky and much less flexible...

"num-ports" is only read in creating the hcd. This value is unchanged
during reconfiguring state.

Reconfiguring is called from usb probe and disconnect callbacks.
So, reconfiguring is called every time unplugging and plugging are
detected.

However, connecting and disconnecting the devices at the same time
or frequent operations were not tested enough.

Do you think it's good idea that the method for the notification
of hotplug is switched from xenbus to RING (like pv network's rx_ring)?

Regards,
Noboru