Re: [RFC net-next 0/4] ethtool: CMIS module diagnostic loopback support

[Björn Töpel]

Hey!

On Mon, 2 Mar 2026 at 10:01, Maxime Chevallier
<maxime.chevallier@xxxxxxxxxxx> wrote:

> The overall approach after all these discussions sounds fine to me, I do
> think that the index of the component that does the loopback needs to be
> there somewhere, when relevant.
>
> Either through a name string, or a combo of an enum indicating the
> component type (MAC/PHY/Module/etc.) + its index. I think it's safe to
> assume that indices will fit in u32 ?
>
> something like :
>
> # MAC PCS loopback
> ethtool --set-loopback eth0 loc mac name pcs
>
> # PHY id 2 PMA loopback (I'm making things up here)
> ethtool --set-loopback eth0 loc phy id 2 name pma
>
> That way we can extend that fairly easily for, say, combo-port devices
> where we could select which of the port we want to loopback :)

Ok! I'll spin a new version with this in mind. To improve my mental
model, could you give an example how you would use a combo-port from a
userland perspective?


Cheers,
Björn