RE: [Xen-devel] HVM Save/Restore status.

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Petersson, Mats
> Sent: 25 April 2007 15:25
> To: Tim Deegan
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Woller, Thomas
> Subject: RE: [Xen-devel] HVM Save/Restore status.
> 
>  
> 
> > -----Original Message-----
> > From: Tim Deegan [mailto:Tim.Deegan@xxxxxxxxxxxxx] 
> > Sent: 25 April 2007 15:09
> > To: Petersson, Mats
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Woller, Thomas
> > Subject: Re: [Xen-devel] HVM Save/Restore status.
> > 
> > Hi, 
> > 
> > At 12:58 +0200 on 25 Apr (1177505885), Petersson, Mats wrote:
> > > My "disk-stress" tests have the following status:
> > > 1. SLES 9.3 using VNC as display has run for over 23 
> > virtual hours, some
> > > 40 or so hours since I set off the test without any failures.
> > 
> > That's great! 
> > 
> > > There's
> > > one difference between this test and previous ones: I've 
> > disabled the
> > > blanking of the screen - there appears to be a problem 
> > waking the screen
> > > after some time, not sure why that would be. 
> > 
> > What are the symptoms there?  Is the guest still alive?  Is qemu-dm
> > alive?  Does it respond on the network, and just have a 
> > wedged console?
> > (Might it be the keyboard + mouse that have got wedged?)
> 
> Good question. It turns out (from an attempt to stop the guest nicely
> when I was going to reboot to have a new Linux-kernel with 
> debug code in
> it) that although the guest is still running, I have actually lost at
> least:
> - Network. I can't ping the guest or SSH to the guest on the 
> IP address
> it used to be when it first got an address from DHCP - presumably, the
> IP address shouldn't change (it doesn't on other machines that get IP
> address from the same DHCP server). 
> - Keyboard. Pressing for example CTRL-C to stop the running 
> application
> doesn't work. No other keys appear to have any effect either.
> 
> It's unclear to me if any other operations are affected or not. [Time
> seemed a bit funny too, but that may be my app - I haven't 
> debugged that
> yet. It kept cycling around a 2-3 second range around 23h14m18-20s (or
> some such), where the time comes from "time()" - so perhaps there's
> something wrong in the "gettimeofday" functionality too.] 
> 
> > 
> > > 2. "Simple-guest" fails to restore on the second restore, 
> > ending up with
> > > the guest "killed". Scanning the xend.log, I find "error 
> > zeroing magic
> > > pages". Looking further down that path, it seems like it's 
> > failing to do
> > > "xc_map_foreign_range"... I'm adding some debug output to try to
> > > determine where it goes wrong here. 
> > 
> > Strange.  Are you doing anything wierd with the ioreq or 
> > xenstore pages
> > in the simple guest?  Their PFNs should have been maintained 
> > across the
> > first save/restore cycle, and they were mappable the first time...
> 
> I'm trying to see what fails and where by printing something at every
> failure point. So far I've tracked it down to somewhere inside the
> function direct_remap_pfn_range... Not sure where in this function it
> goes wrong or where in any of the called functions. As far as 
> I can see,
> there's not many things that can go wrong there... 

Error is 14, which is "EFAULT", which means that the problem appears to
be inside the hypercall. 

I'll see if I can print the different pages involved here. 

Also, I missed answering the question of what I do with those pages:
Nothing. My guest uses about 2MB of the entire 32MB memory range, around
1MB-3MB. 

--
Mats
> 
> --
> Mats
> > 
> > Cheers,
> > 
> > Tim.
> > 
> > -- 
> > Tim Deegan <Tim.Deegan@xxxxxxxxxxxxx>, XenSource UK Limited
> > Registered office c/o EC2Y 5EB, UK; company number 05334508
> > 
> > 
> > 
> 
> 
> 
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