Re: [Xen-devel] [PATCH] Fix device removal on net and block frontend drivers

[Stefan Berger <stefanb@xxxxxxxxxx>]

Murillo Fernandes Bernardes <mfb@xxxxxxxxxx>
wrote on 11/21/2005 11:33:31 AM:

> On Monday 21 November 2005 14:07, Stefan Berger wrote:
> > xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 11/21/2005 10:43:01
AM:
> > > Frontend devices are not being unregistered when in closed
state. The
> > > following patch fix that.
> > >
> > > Fix bug #420.
> > >
> > > Makes "05_attach_and_dettach_device_repeatedly_pos"
and
> > > "09_attach_and_dettach_device_check_data_pos"
tests pass.
> >
> > Did you test this with suspending / resuming a dom U? The reason
I am
> > asking is that when suspending the driver immediately gets into
state
> > 'Closed' and when resuming into state 'Connected',  but
now your device is
> > unregistered.
> 
> No, I did not test suspend/resume.
> 
> I really don't see why it should get into Closed on suspend, but anyway,
is 
> this really hapenning? I could not find any switch to Closed into
suspend's 
> code, neither on resume.
> 
What I am seeing is that after a suspend / resume
the interface 'eth0' is completely gone. 'ifconfig -a' shows everything,
but no eth0.

You might only want to unregister if the domain was
not suspended. So you probably need to implement the .suspend function
in the frontend and set a state variable to know whether the domain is
being hibernated, and you clear that variable in the .resume. You check
that variable when the driver is going into the 'Closed' state and only
unregister if not in 'suspend' mode.

> How to test suspend/resume on a domU? It does not have /sys/power/state
> neither /proc/sleep.

'xm save <dom id> <dom state filename>'
lets you suspend a domain 
'xm restore <dom state filename>' lets you resume
a domain.

I would only use the network driver for testing this
by booting into a RAMDisk.

 Stefan

> 
> -- 
> Murillo Fernandes Bernardes
> IBM Linux Technology Center
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