Xen users - Jun 2011 - could not get IP address for the interface created by netfront driver on HVM guest

Hi,

I am trying to run PV drivers on my HVM guest.
For this, I have compiled 2.6.35.9 kernel downloaded from kernel.org + the
PV-on-HVM drivers patch "pvdrivers.20100509-1955.patch" downloaded
from
http://blog.alex.org.uk/2010/05/09/linux-pv-drivers-for-xen-hvm-building-normally-within-an-arbitrary-kernel-tree/
.
During compilation i disabled "Paravirtualized Guest Support" (and so
"CONFIG_XEN" got disabled) and enabled only "XEN pvdrivers"
from the patch.

The installation of the VM was done using "virt-manager" graphical
utility.
After the installation of VM and the new kernel with PV drivers
compiled/installed on HVM guest, I shutdown the VM, closed the virt-manager,
changed the "vif" configuration in
/var/lib/xend/domains/<UUID>/config.sxp
to "(type netfront)" as below:
    (device
        (vif
            (bridge virbr0)
            (uuid 50c7ccfd-45a7-61df-e94b-52bea67d3ee0)
            (script /etc/xen/scripts/vif-bridge)
            (mac 00:16:36:30:24:8a)
            (type netfront)
            (backend 0)
        )
    )

Then, xend was restarted and virt-manager is restarted and the HVM guest is
started.
The HVM guest boots fine, all the PV drivers are loaded (balloon, vbd, vnif,
platform-pci), network interface is created (also observed Tx/Rx counters
increasing) but it never got IP addresses which otherwise could get in pure
HVM mode. ethtool -i eth0 on the HVM guest shows netfront is the driver for
the interface.

Could you please help me, if I missed something in configuring netfront
device assignment to HVM guest.

Thanks & Regards,
VSR.


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On Sat, Jun 18, 2011 at 4:16 PM, veerasena reddy <veeruyours@gmail.com>
wrote:
> Hi,
>
> I am trying to run PV drivers on my HVM guest.
> For this, I have compiled 2.6.35.9 kernel downloaded from kernel.org + the
> PV-on-HVM drivers patch "pvdrivers.20100509-1955.patch"
downloaded from
>
http://blog.alex.org.uk/2010/05/09/linux-pv-drivers-for-xen-hvm-building-normally-within-an-arbitrary-kernel-tree/.
> During compilation i disabled "Paravirtualized Guest Support"
(and so
> "CONFIG_XEN" got disabled) and enabled only "XEN
pvdrivers" from the patch.
>
> The installation of the VM was done using "virt-manager"
graphical utility.
> After the installation of VM and the new kernel with PV drivers
> compiled/installed on HVM guest, I shutdown the VM, closed the
virt-manager,
> changed the "vif" configuration in
/var/lib/xend/domains/<UUID>/config.sxp
> to "(type netfront)" as below:
>     (device
>         (vif
>             (bridge virbr0)
>             (uuid 50c7ccfd-45a7-61df-e94b-52bea67d3ee0)
>             (script /etc/xen/scripts/vif-bridge)
>             (mac 00:16:36:30:24:8a)
>             (type netfront)
>             (backend 0)
>         )
>     )
>
> Then, xend was restarted and virt-manager is restarted and the HVM guest is
> started.
> The HVM guest boots fine, all the PV drivers are loaded (balloon, vbd,
vnif,
> platform-pci), network interface is created (also observed Tx/Rx counters
> increasing) but it never got IP addresses which otherwise could get in pure
> HVM mode. ethtool -i eth0 on the HVM guest shows netfront is the driver for
> the interface.
>
> Could you please help me, if I missed something in configuring netfront
> device assignment to HVM guest.
>
IP address assignment should be independent of the NIC driver. Could
you do a tcpdump or tshark network trace to see if the DHCP packets
are going and coming in correctly?

You could also try to assign a static IP to and pinging self and the
local network/gateway to see if basic networking is working.

Thanks,
Todd

> Thanks & Regards,
> VSR.
>
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>


-- 
Todd Deshane
http://www.linkedin.com/in/deshantm
http://www.xen.org/products/cloudxen.html
http://runningxen.com/

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Hi,

Thank you very much for the response.
It took little long time as i wanted to do some research from my side before
asking you more.

Please find below my observations:
I did tcpdump on Guest and dom0. On both, Guest and dom0, I could see the
DHCP request from Guest (eth0) to dom0 (virbr0) and DHCP reply from dom0
(virbr0) to Guest (eth0). Please find below the tcpdump output.

When I assigned a static IP address to eth0 interface on Guest (ifconfig
eth0 192.168.122.81), i am able to ping virbr0 (192.168.122.1) on dom0.

And when I explicitly ran dhclient on domU, i observed "5 bad udp checksums
in 5 packets" which was causing drop of packets and the DHCP reply observed
in tcpdump was not reaching DHCP client.
when i disabled Tx checksum on the dom0 vif corresponding to the netfront on
domU, i could successfully get IP address assigned for my interface on
Guest.
# ethtool -K vif1.0 tx off  <<<---- executed on dom0

Any idea why the "bad checksum" happening with PV driver? (while
everything
was fine with pure HVM).

Thanks & Regards,
VSR.

On Sun, Jun 19, 2011 at 6:49 AM, Todd Deshane <todd.deshane@xen.org>
wrote:
> On Sat, Jun 18, 2011 at 4:16 PM, veerasena reddy
<veeruyours@gmail.com>
> wrote:
> > Hi,
> >
> > I am trying to run PV drivers on my HVM guest.
> > For this, I have compiled 2.6.35.9 kernel downloaded from kernel.org +
> the
> > PV-on-HVM drivers patch "pvdrivers.20100509-1955.patch"
downloaded from
> >
>
http://blog.alex.org.uk/2010/05/09/linux-pv-drivers-for-xen-hvm-building-normally-within-an-arbitrary-kernel-tree/
> .
> > During compilation i disabled "Paravirtualized Guest
Support" (and so
> > "CONFIG_XEN" got disabled) and enabled only "XEN
pvdrivers" from the
> patch.
> >
> > The installation of the VM was done using "virt-manager"
graphical
> utility.
> > After the installation of VM and the new kernel with PV drivers
> > compiled/installed on HVM guest, I shutdown the VM, closed the
> virt-manager,
> > changed the "vif" configuration in
> /var/lib/xend/domains/<UUID>/config.sxp
> > to "(type netfront)" as below:
> >     (device
> >         (vif
> >             (bridge virbr0)
> >             (uuid 50c7ccfd-45a7-61df-e94b-52bea67d3ee0)
> >             (script /etc/xen/scripts/vif-bridge)
> >             (mac 00:16:36:30:24:8a)
> >             (type netfront)
> >             (backend 0)
> >         )
> >     )
> >
> > Then, xend was restarted and virt-manager is restarted and the HVM
guest
> is
> > started.
> > The HVM guest boots fine, all the PV drivers are loaded (balloon, vbd,
> vnif,
> > platform-pci), network interface is created (also observed Tx/Rx
counters
> > increasing) but it never got IP addresses which otherwise could get in
> pure
> > HVM mode. ethtool -i eth0 on the HVM guest shows netfront is the
driver
> for
> > the interface.
> >
> > Could you please help me, if I missed something in configuring
netfront
> > device assignment to HVM guest.
> >
>
> IP address assignment should be independent of the NIC driver. Could
> you do a tcpdump or tshark network trace to see if the DHCP packets
> are going and coming in correctly?
>
> You could also try to assign a static IP to and pinging self and the
> local network/gateway to see if basic networking is working.
>
> Thanks,
> Todd
>
>
> > Thanks & Regards,
> > VSR.
> >
> >
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@lists.xensource.com
> > http://lists.xensource.com/xen-users
> >
>
>
>
> --
> Todd Deshane
> http://www.linkedin.com/in/deshantm
> http://www.xen.org/products/cloudxen.html
> http://runningxen.com/
>

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Fri, Jun 24, 2011 at 7:31 PM, veerasena reddy <veeruyours@gmail.com>
wrote:
> And when I explicitly ran dhclient on domU, i observed "5 bad udp
checksums
> in 5 packets" which was causing drop of packets and the DHCP reply
observed
> in tcpdump was not reaching DHCP client.
> when i disabled Tx checksum on the dom0 vif corresponding to the netfront
on
> domU, i could successfully get IP address assigned for my interface on
> Guest.
> # ethtool -K vif1.0 tx off  <<<---- executed on dom0
>
> Any idea why the "bad checksum" happening with PV driver? (while
everything
> was fine with pure HVM).
checksum is kinda on-and-off thing with Xen. At this point I''d suggest
trying later kernels for domU. In particular, Ubuntu''s 2.6.38-server
kernel work fine on my setup (including DHCP). You might want to start
with latest stable kernel (which shouldn''t require any additional
patch).

-- 
Fajar

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Xen-users mailing list
Xen-users@lists.xensource.com
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I have specific requirements to run 2.6.35 kernel.
Could you please suggest if there is any other way to get it working without
Tx checksum off on dom0.

Thanks & Regards,
VSR.

On Fri, Jun 24, 2011 at 6:17 PM, Fajar A. Nugraha <list@fajar.net> wrote:
> On Fri, Jun 24, 2011 at 7:31 PM, veerasena reddy
<veeruyours@gmail.com>
> wrote:
> > And when I explicitly ran dhclient on domU, i observed "5 bad udp
> checksums
> > in 5 packets" which was causing drop of packets and the DHCP
reply
> observed
> > in tcpdump was not reaching DHCP client.
> > when i disabled Tx checksum on the dom0 vif corresponding to the
netfront
> on
> > domU, i could successfully get IP address assigned for my interface on
> > Guest.
> > # ethtool -K vif1.0 tx off  <<<---- executed on dom0
> >
> > Any idea why the "bad checksum" happening with PV driver?
(while
> everything
> > was fine with pure HVM).
>
> checksum is kinda on-and-off thing with Xen. At this point I''d
suggest
> trying later kernels for domU. In particular, Ubuntu''s
2.6.38-server
> kernel work fine on my setup (including DHCP). You might want to start
> with latest stable kernel (which shouldn''t require any additional
> patch).
>
> --
> Fajar
>

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

On Mon, Jun 27, 2011 at 1:07 PM, veerasena reddy <veeruyours@gmail.com>
wrote:
> I have specific requirements to run 2.6.35 kernel.
> Could you please suggest if there is any other way to get it working
without
> Tx checksum off on dom0.
You''re on your own then.

If 2.6.38 works on your system, then you might be able to find out
what changed in xen-netfront in 2.6.35 - 2.6.38. IMHO it''s not worth
the effort though.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users

ok. could you please suggest if there is any configuration option available
(Guest config.sxp) to turn off Tx checksum on my netfront interface so that
everytime the Guest is booted, i do not need to run "ethtool" command.

Thanks & Regards,
VSR.

On Mon, Jun 27, 2011 at 11:56 AM, Fajar A. Nugraha <list@fajar.net> wrote:
> On Mon, Jun 27, 2011 at 1:07 PM, veerasena reddy
<veeruyours@gmail.com>
> wrote:
> > I have specific requirements to run 2.6.35 kernel.
> > Could you please suggest if there is any other way to get it working
> without
> > Tx checksum off on dom0.
>
> You''re on your own then.
>
> If 2.6.38 works on your system, then you might be able to find out
> what changed in xen-netfront in 2.6.35 - 2.6.38. IMHO it''s not
worth
> the effort though.
>
> --
> Fajar
>

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Xen-users mailing list
Xen-users@lists.xensource.com
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