[systemd-devel] Stable interface names even when hardware is added or removed, not true

[Dave Reisner]

On Wed, Nov 16, 2016 at 4:19 PM, Pekka Sarnila <sarnila at adit.fi> wrote:

>
>
> On 11/16/16 18:11, Greg KH wrote:
>
>> On Wed, Nov 16, 2016 at 03:33:42PM +0200, Pekka Sarnila wrote:
>>
>>> On 'Predictable Network Interface Names' it states as a benefit of the
>>> new
>>> policy:
>>>
>>>   Stable interface names even when hardware is added or removed, i.e.
>>>   no re-enumeration takes place
>>>
>>> Unfortunately this is not true.
>>>
>>> I'm running a mail server, kernel 4.8.6. Graphics card started to fail.
>>> Replaced it with new one (newer model). Booted the system.
>>>
>>> All seemed to be fine, network seemed to work. But after some time got
>>> angry
>>> cries: 'can't read the mail !!!'. A big headache.
>>>
>>> Although the new card was in the same slot as the old one kernel had
>>> changed
>>> the name enp6s0 -> enp3s0 (no firmware/BIOS index available and kernel
>>> policy was used as default). Since enp6s0 was not found our server
>>> instead
>>> of fixed ip address used our dhcp-server to get a random temp address.
>>> Thus
>>> network worked, but not in the mail-servers correct address.
>>>
>>> To figure this out took some nervous time.
>>>
>>> Now, I don't know why kernel driver got a different name for this network
>>> interface (ethernet hardware is on the motherboard, and it is the only
>>> net
>>> hardware on the system). But obviously it can happen.
>>>
>>
>> That is because your PCI devices renumbered themselves, which is quite
>> common when changing PCI devices around (or adding/removing them).  Not
>> much systemd can do about this, sorry.
>>
>> greg k-h
>>
>>
> Well my first point was that the web page should not say
>
> >>   Stable interface names even when hardware is added or removed, i.e.
> >>   no re-enumeration takes place
>
> But second was that in principle persistent naming would be possible for
> systems with only one interface. And it should possible to implement it in
> systemd-network, and make it systemd package default for such case.


No, it's not. It sounds more like you want to disable the naming policy,
which means you get "eth0" for the first device that shows up.


>
> pekka
>
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