[vbox-dev] FW: Re: [VBox-users] Predictable PCI bus addresses for network interfaces?

Klaus Espenlaub klaus.espenlaub at oracle.com
Mon Jul 15 02:11:33 PDT 2013

Hi Kent,

On 10.07.2013 22:49, Kent R. Spillner wrote:
> Forwarding to the dev list because I never received a response on the users list. :)
> -----Original Message-----
> From: "Kent R. Spillner" <kspillner at acm.org>
> Sent: Sunday, June 23, 2013 08:53
> To: "Community mailing list of VirtualBox users" <vbox-users-community at lists.sourceforge.net>
> Subject: Re: [VBox-users] Predictable PCI bus addresses for network interfaces?
> Bump.
> On Jun 3, 2013, at 14:57, "Kent R. Spillner" <kspillner at acm.org> wrote:
>> Howdy-
>> Is it possible to predict PCI bus addresses for network interfaces?

Of course. The PCI bus addresses for each PCI device in VirtualBox are 
100% deterministic, and only switching to a different chipset type 
(which we don't encourage, as ICH9 is marked as experimental) will 
select a different (again 100% deterministic) mapping.

>> Is the mapping from VirtualBox network adapter "slot" to PCI bus address stable, meaning it won't change from host to host or from guest to guest?
>> What variables affect the mapping of VirtualBox network adapter slot to PCI bus address?  Chipset?  Network adapter type?  The presence or absence of VirtualBox extensions?

Only chipset plays a role, as it also determines the bus topology (and 
thus the number of supported PCI devices).


>> I'm curious because Systemd v197 changed the default way network interfaces are named (see: http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/), and I'm just trying to gauge the potential impact to Linux guests.  For example, can I assume that the first network adapter will always attach to bus 0 slot 17 (0x11), the second network adapter will always attach to bus 0 slot 8 (0x08), etc?  Or are those mappings specific to guests using the PIIX3 chipset and Intel 82545EM and 82540EM adapter types?

No idea how you came to the conclusion that the first NIC is bus 0/dev 
17, as this is what the 6th NIC will get. The fist NIC is bus 0/dev 3, 
unless someone knows the magic tricks to enable compatibility with 
VMware, which puts its first NIC at bus 0/dev 11.

>> Thanks in advance!

Hope this helps,

>> Best,
>> Kent

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