Re: [Xen-devel] HVM guest sees two NICs even though just one vif configured

["Ky Srinivasan" <ksrinivasan@xxxxxxxxxx>]

>>> On 8/6/2009 at  5:32 AM, in message
<0199E0D51A61344794750DC57738F58E6D6A501125@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Fischer, Anna" <anna.fischer@xxxxxx> wrote: 
> I am running SLES10 with Xen 3.2 and I have configured an HVM guest. 
What version of sles10 are you installing? In sles10 sp3, if you install with 
our tools you automatically get PV drivers (both NIC and disk) enabled. Our 
tools will generate the appropriate config file (with type=netfront) and 
appropriate kernel boot option to disable probing of the hard disk. Prior to 
sles10 SP3, one had to manually enable PV drivers after installing using the 
emulated devices.

Regards,

K. Y
> 
> I configured the guest with a single virtual NIC:
> 
> vif = [ 'bridge=eth0, mac=00:16:3e:00:31:13' ]
> 
> I have not configured type=ioemu or type=netfront here, as you can see.
> 
> Now what happens is that on Dom0 Xen creates a tap device connecting to QEMU 
> emulating a RTL 8139 NIC, and additionally a vifX device for the traditional 
> PV approach. Both devices are connected to the bridge eth0.
> 
> Now within my HVM guest I can see the RTL 8139 under lspci. However, I also 
> have the xen-vnif driver installed inside the guest OS as it provides much 
> better performance. On boot xen-vnif successfully connects the netfront to 
> the 
> netback driver and basically I have a proper PV connection that my guest can 
> now use. It shows up as say eth0. At this point the guest will use eth0 and 
> the PV drivers to do networking.
> 
> But still the guests sees as second NIC, the RTL 8139, and if I load the 
> 8139too driver inside the guest, then the guest can additionally activate 
> that second NIC, say as eth1. By default it is configured with the same MAC 
> address as eth0 but I can easily change that within the guest OS. From that 
> point on, my guest has two working NICs, with different MACs and so different 
> IPs. 
> 
> For me this does not sound right. If I configure my guest with only a single 
> NIC in the configuration file, then there should not be any way for the guest 
> to set up and use two NICs at the same time. 
> 
> Is this a known issue? How is this supposed to be handled?
> 
> Thanks,
> Anna
> 
> 
> My Xen version:
> 
> xm info
> release                : 2.6.16.60-0.21-xen
> version                : #1 SMP Tue May 6 12:41:02 UTC 2008
> machine                : x86_64
> nr_cpus                : 8
> nr_nodes               : 1
> cores_per_socket       : 4
> threads_per_core       : 1
> cpu_mhz                : 2700
> hw_caps                : 
> 178bf3ff:efc3fbff:00000000:00000110:00802001:00000000:000037ff
> total_memory           : 65533
> free_memory            : 4141
> max_free_memory        : 54085
> max_para_memory        : 54081
> max_hvm_memory         : 53946
> node_to_cpu            : node0:0-7
> xen_major              : 3
> xen_minor              : 2
> xen_extra              : .0_16718_14-0.4
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 
> hvm-3.0-x86_32p hvm-3.0-x86_64 
> xen_scheduler          : credit
> xen_pagesize           : 4096
> platform_params        : virt_start=0xffff800000000000
> xen_changeset          : 16718
> cc_compiler            : gcc version 4.1.2 20070115 (SUSE Linux)
> cc_compile_by          : abuild
> cc_compile_domain      : suse.de
> cc_compile_date        : Tue May  6 15:20:41 UTC 2008
> xend_config_format     : 4
> 
> 
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