Xen devel - Jun 2007 - troubles using network boot with HVM guest

Hello.

I tried to boot from network with HVM guest, using guest=''n''
configuration value. The DHCP query is correctly send to the server, and
the answer is propagated to the virtual domain interface, as
demonstrated by tcpdump capture (included). However, it seems the
etherboot image included in xen isn''t able to process it correctly, all
I have is ''no ip address'' error message.

I''ve tried both bridging and routing network setup, without
differences.
I also tried non-default interface models (''ne2k_pci'' results
in ''no
bootable device found'' error message, and ''pcnet32''
result in a domain
unavailable through vnc).

I''ve googled at bit on the issue, and I found references to this
discussion:
http://lists.xensource.com/archives/html/xen-devel/2006-08/msg00009.html

if I understand correctly, PXE boot was a known issue at least 10 month
ago... What is current status in xen 3.1 ?

-- 
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62


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Hi, 

At 14:27 +0200 on 04 Jun (1180967227), Guillaume Rousse
wrote:
> I tried to boot from network with HVM guest, using
guest=''n''
> configuration value. The DHCP query is correctly send to the server, and
> the answer is propagated to the virtual domain interface, as
> demonstrated by tcpdump capture (included). However, it seems the
> etherboot image included in xen isn''t able to process it
correctly, all
> I have is ''no ip address'' error message.
:( Works fine for me.  What DHCP server are you using?  Do you have any
firewall/packet-filter/selinux/etc config in your dom0 that might be
supressing the response?
> I''ve googled at bit on the issue, and I found references to this
discussion:
> http://lists.xensource.com/archives/html/xen-devel/2006-08/msg00009.html
> 
> if I understand correctly, PXE boot was a known issue at least 10 month
> ago... What is current status in xen 3.1 ?
That''s a long time out of date.  PXE booting of HVM guests went into
the
Xen HVM BIOS/loader about six months ago.

Cheers,

Tim.

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

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Tim Deegan a écrit :
> Hi, 
> 
> At 14:27 +0200 on 04 Jun (1180967227), Guillaume Rousse wrote:
>> I tried to boot from network with HVM guest, using
guest=''n''
>> configuration value. The DHCP query is correctly send to the server,
and
>> the answer is propagated to the virtual domain interface, as
>> demonstrated by tcpdump capture (included). However, it seems the
>> etherboot image included in xen isn''t able to process it
correctly, all
>> I have is ''no ip address'' error message.
> 
> :( Works fine for me.  What DHCP server are you using?  Do you have any
> firewall/packet-filter/selinux/etc config in your dom0 that might be
> supressing the response?
dhcp-server 3.0.4. And DHCP works fine from an installed guest domain.

And as stated in my initial message, I see response packet arriving on
the bridged interface (xenbr0), as well as on the guest domain virtual
interface (vif13.0 in the given capture file). Hence my assumption than
network setup and server is OK, and problem comes from emulated network
card.

As a potential issue, dhcp reply comes from another network, through a
proxy. I once had troubles with windows client ignoring those answers if
their origin was not strictly set to the local network broadcast adress.
-- 
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62

_______________________________________________
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Guillaume Rousse wrote:
> Hello.
> 
> I tried to boot from network with HVM guest, using
guest=''n''
> configuration value. The DHCP query is correctly send to the server, and
> the answer is propagated to the virtual domain interface, as
> demonstrated by tcpdump capture (included). However, it seems the
> etherboot image included in xen isn''t able to process it
correctly, all
> I have is ''no ip address'' error message.
> 
> I''ve tried both bridging and routing network setup, without
differences.
> I also tried non-default interface models (''ne2k_pci''
results in ''no
> bootable device found'' error message, and
''pcnet32'' result in a domain
> unavailable through vnc).
> 
> I''ve googled at bit on the issue, and I found references to this
discussion:
> http://lists.xensource.com/archives/html/xen-devel/2006-08/msg00009.html
> 
> if I understand correctly, PXE boot was a known issue at least 10 month
> ago... What is current status in xen 3.1 ?

What are you trying to pxeboot?  I''ve heard of people having issues 
booting some versions of syslinux with etherboot.

Regards,

Anthony Liguori
> 
> 
> ------------------------------------------------------------------------
> 
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Anthony Liguori a écrit :
>> if I understand correctly, PXE boot was a known issue at least 10 month
>> ago... What is current status in xen 3.1 ?
> 
> 
> What are you trying to pxeboot?  I''ve heard of people having
issues
> booting some versions of syslinux with etherboot.
I''m just using xen network boot option (boot=''n'' in
guest
configuration), nothing else. And I don''t even get to the stage of
actually booting the recovered image, as received DHCP reply seems to be
ignored.

-- 
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62

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Guillaume Rousse wrote:
> Anthony Liguori a écrit :
>   
>>> if I understand correctly, PXE boot was a known issue at least 10
month
>>> ago... What is current status in xen 3.1 ?
>>>       
>> What are you trying to pxeboot?  I''ve heard of people having
issues
>> booting some versions of syslinux with etherboot.
>>     
> I''m just using xen network boot option (boot=''n''
in guest
> configuration), nothing else. And I don''t even get to the stage of
> actually booting the recovered image, as received DHCP reply seems to be
> ignored.
>   
What''s your dhcp server?

Regards,

Anthony Liguori



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Anthony Liguori a écrit :
>> I''m just using xen network boot option
(boot=''n'' in guest
>> configuration), nothing else. And I don''t even get to the
stage of
>> actually booting the recovered image, as received DHCP reply seems to
be
>> ignored.
>>   
> 
> What''s your dhcp server?
dhcp-server 3.0.4
-- 
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62

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At 14:58 +0200 on 04 Jun (1180969137), Guillaume Rousse
wrote:
> As a potential issue, dhcp reply comes from another network, through a
> proxy. I once had troubles with windows client ignoring those answers if
> their origin was not strictly set to the local network broadcast adress.
>From a quick rummage around in the packet trace, it looks like the DHCP
siaddr ("next server to contact") field in the reply packet is set to
zero, and etherboot explicitly discards dhcp replies where that field is
zero.  (Disclaimer: this is based on about ten minutes of poking at the
etherboot source and RFC2131 -- I am by no means a DCHP expert).

Can you check the DHCP server settings, and whether your proxy is doing
something wierd to the packet? 

Tim.

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

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Tim Deegan a écrit :
> At 14:58 +0200 on 04 Jun (1180969137), Guillaume Rousse wrote:
>> As a potential issue, dhcp reply comes from another network, through a
>> proxy. I once had troubles with windows client ignoring those answers
if
>> their origin was not strictly set to the local network broadcast
adress.
> 
> From a quick rummage around in the packet trace, it looks like the DHCP
> siaddr ("next server to contact") field in the reply packet is
set to
> zero, and etherboot explicitly discards dhcp replies where that field is
> zero.  (Disclaimer: this is based on about ten minutes of poking at the
> etherboot source and RFC2131 -- I am by no means a DCHP expert).
> 
> Can you check the DHCP server settings, and whether your proxy is doing
> something wierd to the packet? 
I did check with a real host, it worked perfectly. But you find the
issue: the server was only answering PXE requests, whereas the emulated
network card send an etherboot one.Just adding etherboot configuration
on the server was enough to provide a functional answer.

I was able to make the virtual domain download a grub stage2 built for
rtl839. As I was not able to rebuild grub myself (compilation errors), I
used this one
http://cvs.mandriva.com/cgi-bin/viewvc.cgi/gi/tools/i386/netboot/rtl8139/?pathrev=MDK-2006_0-update

Once loaded, the virtual host send a new DHCP request, and then ignore
the answer once again, despite the fact than the next-server field is
correct. According to my knowledge, it should finish the DHCP
transaction, then requires /boot/grub/menu.list from the tftp server.

I''m joining the new traffic capture again. Any hint welcome,
I''m a bit
lost in netboot subtilities :)
-- 
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62



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At 16:34 +0200 on 06 Jun (1181147651), Guillaume Rousse
wrote:
> Tim Deegan a écrit :
> > Can you check the DHCP server settings, and whether your proxy is
doing
> > something wierd to the packet? 
> 
> I did check with a real host, it worked perfectly.
Was your test host using an rtl8139 and etherboot?  Did grub work on it?
> But you find the
> issue: the server was only answering PXE requests, whereas the emulated
> network card send an etherboot one.Just adding etherboot configuration
> on the server was enough to provide a functional answer.
Great!
 
> I was able to make the virtual domain download a grub stage2 built for
> rtl839. As I was not able to rebuild grub myself (compilation errors), I
> used this one
>
http://cvs.mandriva.com/cgi-bin/viewvc.cgi/gi/tools/i386/netboot/rtl8139/?pathrev=MDK-2006_0-update
> 
> Once loaded, the virtual host send a new DHCP request, and then ignore
> the answer once again, despite the fact than the next-server field is
> correct. According to my knowledge, it should finish the DHCP
> transaction, then requires /boot/grub/menu.list from the tftp server.
Aiee!  Grub will be using its own driver and IP stack, so presumably has
other restrictions on what it thinks a DHCP response should look like.
Have you considered using pxelinux? :)

Cheers,

Tim.

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

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Tim Deegan a écrit :
> At 16:34 +0200 on 06 Jun (1181147651), Guillaume Rousse wrote:
>> Tim Deegan a écrit :
>>> Can you check the DHCP server settings, and whether your proxy is
doing
>>> something wierd to the packet? 
>> I did check with a real host, it worked perfectly.
> 
> Was your test host using an rtl8139 and etherboot?  Did grub work on it?
Now, it was standard PXE. I never had to use anything else sofar, hence
my current troubles.
>> But you find the
>> issue: the server was only answering PXE requests, whereas the emulated
>> network card send an etherboot one.Just adding etherboot configuration
>> on the server was enough to provide a functional answer.
> 
> Great!
>  
>> I was able to make the virtual domain download a grub stage2 built for
>> rtl839. As I was not able to rebuild grub myself (compilation errors),
I
>> used this one
>>
http://cvs.mandriva.com/cgi-bin/viewvc.cgi/gi/tools/i386/netboot/rtl8139/?pathrev=MDK-2006_0-update
>>
>> Once loaded, the virtual host send a new DHCP request, and then ignore
>> the answer once again, despite the fact than the next-server field is
>> correct. According to my knowledge, it should finish the DHCP
>> transaction, then requires /boot/grub/menu.list from the tftp server.
> 
> Aiee!  Grub will be using its own driver and IP stack, so presumably has
> other restrictions on what it thinks a DHCP response should look like.
> Have you considered using pxelinux? :)
You know what ? I was persuaded than pxelinux was not compatible with
etherboot, just from the only PXE documentation I had... I just changed
my configuration to use my already existing pxelinux configuration, and
everything works like a charm...

Thanks a lot for your suggestion :)
-- 
Guillaume Rousse
Moyens Informatiques - INRIA Futurs
Tel: 01 69 35 69 62

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