Re: Auto-negotiation - Out of business

[Francesco Giudici <fgiudici redhat com>]

On 24/11/2016 12:08, Thomas Haller wrote:

> in the past (up until today) nm-connection-editor always set duplex to
> "full", although the value was not implemented by the server. Thus,
> every connection created in the past will change behavior after the
> update.
>
> to fix that, keyfile must ignore the old values like
>
>   [ethernet]
>   duplex=full
>
> and treat them as unset.
>
> Of course, we need a new way to encode full/half in keyfile, let's fix
> keyfile reader/writer to instead use:
>
>   [ethernet]
>   duplex=f
>   duplex=h
>
>
>
>
> For the speed value, there is not problem, because nm-c-e would always
> set it to 0, which is anyway what we want.
>
>
>
> For the autonegotiation value, there is a problem:
>
>  a)  old nm-c-e would set it to TRUE, with old libnm, old NM would not persist (good)
>  b1) old nm-c-e would set it to TRUE, with new libnm, new NM would persist as TRUE (wrong)
>
> nm-c-e must be fixed to not touch the default value for autonegotiation, so it would be
>
>  b2) new nm-c-e would not set autonet, which old libnm would not transfer via D-Bus (and new NM wuold not 
> persist) good
>  b3) new nm-c-e would not set autonet, which new libnm would not transfer via D-Bus (and new NM wuold not 
> persist) good
>
> Note that b1) cannot be fixed, although it's a supported combination.
> E.g. running nm-c-e 1.4.2 with libnm 1.5.3 against server 1.5.3.
> It's a bug in nm-c-e, the solution is to upgrade to a fixed version.
>
>
> Needs fix in both nm-c-e and in keyfile reader/writer.

Instead of changing the keyfile, I would just more careful in enforcing
the autonegotiate to manual: in case of autonegotiation disabled and
just one among speed=0 and duplex=NULL, I would ignore the link
configuration and put a warning in logs. After all, putting there both
speed and duplex is expected when one wants to set link negotiation
manually. Otherwise, the missing settings will be random.
This would also good for b1).

Poma, thanks for reporting this early.

Francesco