Re: [Xen-devel] [BUG] Xen vm kernel crash in get_free_entries.

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Sander Eikelenboom [mailto:linux@xxxxxxxxxxxxxx]
> Sent: 18 October 2013 12:28
> To: Paul Durrant
> Cc: Ian Campbell; David Vrabel; Stefano Stabellini; Astarta; xen-
> devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [BUG] Xen vm kernel crash in get_free_entries.
> 
> 
> Friday, October 18, 2013, 1:06:52 PM, you wrote:
> 
> >> -----Original Message-----
> >> From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-
> >> bounces@xxxxxxxxxxxxx] On Behalf Of Ian Campbell
> >> Sent: 18 October 2013 10:46
> >> To: David Vrabel
> >> Cc: xen-devel@xxxxxxxxxxxxx; Astarta; Stefano Stabellini
> >> Subject: Re: [Xen-devel] [BUG] Xen vm kernel crash in get_free_entries.
> >>
> >> On Fri, 2013-10-18 at 10:31 +0100, David Vrabel wrote:
> >>
> >> > I suspect some of the changes for ARM has caused this (because ARM is
> >> > sort of PVHVM without a platform PCI device) but I had a quick look and
> >> > couldn't spot anything.  Stefano, any ideas?
> >>
> >> If there is no platform device then we should never be going anywhere
> >> near any of the grant table code...
> >>
> >> From the log in the original post it looks like at least some parts of
> >> the kernel think it is running PVHVM (i.e. it does the unplug and says
> >> "Booting paravirtualized kernel on Xen HVM"). I don't think this should
> >> not be the case if there is no platform pci device.
> >>
> >> Could this be because XenServer uses this platform_device=2 thing,
> which
> >> is enough to trigger some of the early setup (because the unplug
> >> protocol is present on I/O ports 0x10) but then the PCI driver in Linux
> >> doesn't know about this ID and so never initialises the rest of it?
> >>
> >> Astarta, which of these configurations have you tried:
> >>
> >>  - No platform device at all
> >>  - Platform device with ID == 1
> >>  - Platform device with ID == 2
> >>
> >> and what happened with each?
> >>
> 
> > device_id will be 2 only if you use a windows template - which you
> generally should not for hvm linux as that also has viridian=true.
> 
> What option sets the device id to 2 in a cfg file ?
> I have encountered it on the "normal" xen project as well, so it's not only
> xenserver.
> 

The device_id hack is only in XenServer.

  Paul

> No other related options in my cfg file as far as i see, only the
> xen_platform_pci=0
> 
> It seemed to be introduced in the 3.8 kernel series.
> 
> --
> Sander
> 
> >   Paul
> 
> 


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