Re: [Xen-devel] error when pass through device to guest with qemu-xen-dir-remote

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Zhang, Yang Z wrote on 2012-09-11:
>  wrote on August 09, 2012 2:49 PM To: Ian Campbell; Stefano Stabellini:
>> I rebuild the upstream QEMU according to the wiki, but device static
>> assignment doesn't work, no lspci output in guest. However hotplug &
>> unplug works fine.
>> 
>> -----Original Message----- From: xen-devel-bounces@xxxxxxxxxxxxx
>> [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Ian Campbell Sent:
>> Friday, August 03, 2012 6:36 PM To: Stefano Stabellini Cc: Zhang, Yang
>> Z; Anthony Perard; xen-devel Subject: Re: [Xen-devel] error when pass
>> through device to guest with qemu-xen-dir-remote
>> 
>> On Fri, 2012-08-03 at 11:29 +0100, Stefano Stabellini wrote:
>>> On Fri, 3 Aug 2012, Zhang, Yang Z wrote:
>>>> When create guest with device assigned, it shows the error and the
>>>> device wasn't able to work inside guest: libxl: error:
>>>> libxl_qmp.c:288:qmp_handle_error_response: received an error message
>>>> from QMP server: Parameter 'driver' expects a driver name
>>>> 
>>>> It only fails with qemu-xen-dir-remote(Is this tree more close to
>>>> upstream qemu?). I don't see the error with the traditional Qemu. I
>>>> also tried qemu-upstream, but it fails when I try to enable pci
>>>> pass-through
>> for xen. I think Anthony's patch to add pci pass-through support for Xen is
>> accepted by qemu-upstream, am I right?
>>> 
>>> Yes, it was accepted, but it is present only in upstream QEMU (from
>>> git://git.qemu.org/qemu.git), not the tree we are currently using in
>>> xen-unstable for development
>>> (git://xenbits.xensource.com/qemu-upstream-unstable.git).
>>> Make sure you are using the right tree!
>> 
>> http://wiki.xen.org/wiki/QEMU_Upstream has some notes on how to use the
>> upstream qemu tree instead of our stable branch of upstream.
>> 
>>> 
>>> Anthony is currently on vacation and is going to be back in about a
>>> week.
>>> 
>>>> Another question:
>>>> Now I am trying to add some features (relevant to pass through device) to
>> Qemu, which tree should I use? Since traditional qemu is great
>> different from qemu-upstream, it is too old to develop patch base on
>> it. But besides the old one, I cannot find a working qemu.
>>> 
>>> You should use upstream QEMU, I am going to rebase our tree on that
>>> early on in the 4.3 release cycle.
> 
> Hi Anthony
> 
> I found the issue is caused by PV driver. Since RHEL6 integrated PV driver by
> default, when booting rhel6 as guest, it will load the PV driver and write 
> the xen
> platform device to notify qemu to unplug all NICs including the pass through
> device. This definitely is wrong. We only need to unplug the emulator device, 
> and
> leave pass through device.

Hi Anthony,

Any comments for this?

Best regards,
Yang



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