Xen devel - Mar 2013 - failed to unplug qemu devices

I just had a DomU start up where for some reason the qemu devices failed to be
unplugged. Fortunately Windows saw this as two paths to the same disk instead of
two separate disks so nothing got scrambled, but the network was dropping out
all the time etc.

Are there any circumstances under which the qemu unplug could fail to work? And
if so, how could I tell?

More likely some race condition in GPLPV but I first want to discount the
possibility that qemu might fail to unplug.

Thanks

James

> -----Original Message-----
> From: xen-devel-bounces@lists.xen.org [mailto:xen-devel-
> bounces@lists.xen.org] On Behalf Of James Harper
> Sent: 16 March 2013 23:38
> To: xen-devel@lists.xensource.com
> Subject: [Xen-devel] failed to unplug qemu devices
> 
> I just had a DomU start up where for some reason the qemu devices failed to
> be unplugged. Fortunately Windows saw this as two paths to the same disk
> instead of two separate disks so nothing got scrambled, but the network was
> dropping out all the time etc.
> 
> 
> Are there any circumstances under which the qemu unplug could fail to
> work? And if so, how could I tell?
> 
Which QEMU are you using? The most common case for unplug failure I encounter
with traditional is a driver blacklisting issue and the protocol tells you via
the magic number from port 0x10. If this is good then the unplug should be ok. I
don''t know whether anyone has ported the blacklisting handshake to
upstream QEMU though; I don''t have code to hand.

  Paul
> More likely some race condition in GPLPV but I first want to discount the
> possibility that qemu might fail to unplug.
> 
> Thanks
> 
> James
> 
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