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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-11-12 at 10:56 -0500, Konrad Rzeszutek Wilk wrote:
> On Thu, Nov 07, 2013 at 01:47:03PM +0000, Ian Campbell wrote:
> > On Thu, 2013-11-07 at 09:20 +0400, Astarta wrote:
> > > Hello,
> > > 
> > > Let me bring some new life to this discussion.
> > > 
> > > I've investigated a bit and found another way to make  kernels starting 
> > > from 3.8.x to boot on the VMs with platform device_id 0002.
> > > Reverting of xen-grant-table-correctly-initialize-grant-table-version-1 
> > > patch is not necessary.
> > > 
> > > We can simply modify struct pci_device_id platform_pci_tbl[] (in 
> > > drivers/xen/platform-pci.c) to respect 0002 and 0000 device ids.
> > > That makes the kernel (3.8.x and 3.11.6) to boot correctly, disks and 
> > > network are also recognized.
> > 
> > I think this is just working around the problem, by avoiding the
> > situation where the error occurs. You could just as well switch to
> > platform device id < 2.
> 
> I am bit late to this discussion - but shouldn't there be something
> in the kernel to deal with this?

Well, ideally the kernel wouldn't crash ;-)

I don't think it would be appropriate for Linux to bind to the device
with ID 2, since that has been assigned to a vendor
http://xenbits.xen.org/docs/unstable/hypercall/x86_64/include,public,hvm,pvdrivers.h.html
it should be up to them to define the ABI of that device and provide a
Linux binding if they want.

Perhaps the unplug protocol
http://xenbits.xen.org/docs/unstable/misc/xen-command-line.html needs
expanding to blacklist products based on the presence absence of
whichever platform device subids there are.

I'm a bit confused because I thought the requirement was that the base
level platform device was always present and the secondary ones (like
the Citrix PV device with ID 2) would only ever be additional. Maybe I'm
wrong about that.

Ian.


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