suppressing warning about unavailable link speed

suppressing warning about unavailable link speed

[Rustam]

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When I try to configure batman_adv on a bridge interface, I get this
warning from the kernel:

> batman_adv: bat0: WiFi driver or ethtool info does not provide
information about link speeds on interface br0.100, therefore defaulting to
hardcoded throughput values of 1.0 Mbps. Consider overriding the throughput
manually or checking your driver.

It seems there is no way to suppress it.

I could do `batctl hardif br0.100 to 100000` but only *after* I add the
interface and get the above warning.

So here's a suggestion - maybe there could be a "default link speed"
setting, which, when set, would also suppress the warning?
And/or allow setting the link speed override *before* adding the interface.
Then we could patch systemd-networkd to make it configurable.

Or perhaps expand link speed detection to descend into bridges and grab the
underlying link speeds?

---
To prevent discussion about why I'm adding a bridge interface instead of
underlying ports, it's because my ethernet has loops and I have STP
enabled, and STP doesn't interoperate with batman_adv at all, plus I have
other services that run outside batman_adv so I have to keep the bridge
with STP on.

Thanks in advance for any reaction on this matter,

Cheers
Rustam

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Re: suppressing warning about unavailable link speed

[Marek Lindner]

On Monday, June 9, 2025 9:08:07 PM Central European Summer Time Rustam wrote:
> It seems there is no way to suppress it.
> 
> I could do `batctl hardif br0.100 to 100000` but only *after* I add the
> interface and get the above warning.

By default batman-adv attempts to determine the link speed automagically. That 
is why you see a warning every time that magic fails.


> So here's a suggestion - maybe there could be a "default link speed"
> setting, which, when set, would also suppress the warning?
> And/or allow setting the link speed override *before* adding the interface.
> Then we could patch systemd-networkd to make it configurable.

Having a default setting for manual link speed is not a bad idea. You'd have 
to document well whether this default speed comes into effect only when the 
auto-link-speed detection has failed or always.

Feel free to propose a patch.


> Or perhaps expand link speed detection to descend into bridges and grab the
> underlying link speeds?

Afaik br0.100 is a VLAN interface which does not provide link speeds on its 
down.

Automatic link detection on the underlying bridge interface will be tricky. If 
the bride contains multiple slave interfaces which link speed should be used?

Cheers,
Marek