Mailing List Archive: Restricting number of nics seen by Domain 0

Restricting number of nics seen by Domain 0

May 26, 2005, 8:39 AM

Post #1 of 7 (935 views)

Is it possible to disable one of the (real) Ethernet interfaces from Xen so
that Domain 0 doesn't see it? I.e. when the Domain 0 XenLinux boots up it
only has eth0 although there are actually two NICs in the machine. Would it
be possible to do this using the "nics=" parameter? I know this can be done
for doms>0 but get the impression Domain 0 is different.

Alternatively if there is a Linux kernel parameter that can be used to
disable a NIC that would also do. (I have accidentally configured two NICs
with the same IP address and can't log into the (remote) machine over the
network, but I can get to the grub prompt over a serial-over-lan console so
hence am limited to what can be done with Xen/XenLinux kernel parameters).

Stephen

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Re: Restricting number of nics seen by Domain 0 [ In reply to ]

andrewkt at aktzero

May 26, 2005, 9:16 AM

Post #2 of 7 (922 views)

Permalink

Stephen Childs wrote:
> Alternatively if there is a Linux kernel parameter that can be used to
> disable a NIC that would also do. (I have accidentally configured two
> NICs with the same IP address and can't log into the (remote) machine
> over the network, but I can get to the grub prompt over a
> serial-over-lan console so hence am limited to what can be done with
> Xen/XenLinux kernel parameters).

(Tossing idea) Does single or nonetwork mode present you with a login
prompt over your serial connection?

You can try booting one of your domU's directly with the dom0 kernel. If
you're not doing anything funky with your networking, that should allow
you to ssh in and mount the other drive and fix your nic error.

--
Andrew Thompson
http://aktzero.com/

Re: Restricting number of nics seen by Domain 0 [ In reply to ]

childss at cs

May 26, 2005, 9:21 AM

Post #3 of 7 (919 views)

Permalink

Andrew Thompson wrote:
> Stephen Childs wrote:
>
>> Alternatively if there is a Linux kernel parameter that can be used to
>> disable a NIC that would also do. (I have accidentally configured two
>> NICs with the same IP address and can't log into the (remote) machine
>> over the network, but I can get to the grub prompt over a
>> serial-over-lan console so hence am limited to what can be done with
>> Xen/XenLinux kernel parameters).
>
>
> (Tossing idea) Does single or nonetwork mode present you with a login
> prompt over your serial connection?

No. It's an Intel board with the BMC management interface but I have yet to
get anything other than a grub prompt over it despite trying various
console=ttyS? options on the XenLinux kernel command line.

> You can try booting one of your domU's directly with the dom0 kernel. If
> you're not doing anything funky with your networking, that should allow
> you to ssh in and mount the other drive and fix your nic error.

Unfortunately the domU is hosted on a file rather than a partition so I
don't think I can start it directly. In fact I'm not even sure I'd finished
setting up the domU properly.

Stephen
--
Dr. Stephen Childs,
Research Fellow, EGEE Project, phone: +353-1-6081797
Computer Architecture Group, email: Stephen.Childs @ cs.tcd.ie
Trinity College Dublin, Ireland web: http://www.cs.tcd.ie/Stephen.Childs

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Re: Restricting number of nics seen by Domain 0 [ In reply to ]

kju at fqdn

May 26, 2005, 9:28 AM

Post #4 of 7 (921 views)

Permalink

> No. It's an Intel board with the BMC management interface but I have yet to
> get anything other than a grub prompt over it despite trying various
> console=ttyS? options on the XenLinux kernel command line.

Thats because having a console on ttyS0 does not also start a putty on it.
Try passing something like console=ttyS0,57600 init="/sbin/getty -L ttyS0
57600 vt100".

Regards
Michael

--
It's an insane world, but i'm proud to be a part of it. -- Bill Hicks

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Re: Restricting number of nics seen by Domain 0 [ In reply to ]

kju at fqdn

May 26, 2005, 9:32 AM

Post #5 of 7 (923 views)

Permalink

> Thats because having a console on ttyS0 does not also start a putty on it.

Should read "getty" of course. If you have finally managed to get into your
system, immediately fix your inittab to call a getty process on ttyS0 like
this way:

T0:23:respawn:/sbin/getty -L ttyS0 57600 vt100

Regards
Michael

--
It's an insane world, but i'm proud to be a part of it. -- Bill Hicks

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Re: Restricting number of nics seen by Domain 0 [ In reply to ]

slapic at linux

May 27, 2005, 10:42 AM

Post #6 of 7 (923 views)

Permalink

2005-05-26, cs keltezéssel 16.39-kor Stephen Childs ezt írta:
> Alternatively if there is a Linux kernel parameter that can be used to
> disable a NIC that would also do. (I have accidentally configured two NICs
> with the same IP address and can't log into the (remote) machine over the
> network, but I can get to the grub prompt over a serial-over-lan console so
> hence am limited to what can be done with Xen/XenLinux kernel parameters).

You can hide a pci device if you know its id.
Add this to xen's boot parameters (kernel xen.gz etc...):
physdev_dom0_hide=(01:00.0)
this will hide the pci device 01:00.0 from domain0.
You still have to guess the right id... normally lspci does it.

Regards,
Slapic

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Re: Restricting number of nics seen by Domain 0 [ In reply to ]

andrewkt at aktzero

May 27, 2005, 10:50 AM

Post #7 of 7 (923 views)

Permalink

>>Alternatively if there is a Linux kernel parameter that can be used to
>>disable a NIC that would also do. (I have accidentally configured two NICs
>>with the same IP address and can't log into the (remote) machine over the
>>network, but I can get to the grub prompt over a serial-over-lan console so
>>hence am limited to what can be done with Xen/XenLinux kernel parameters).

To the original poster, have you resolved this yet?

What did you do?

--
Andrew Thompson
http://aktzero.com/

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