Re: [PATCH net-next v4 2/6] netdev_features: remove unused __UNUSED_NETIF_F_1

[Eric Dumazet]

On Wed, Aug 21, 2024 at 5:07 PM Alexander Lobakin
<aleksander.lobakin@xxxxxxxxx> wrote:
>
> NETIF_F_NO_CSUM was removed in 3.2-rc2 by commit 34324dc2bf27
> ("net: remove NETIF_F_NO_CSUM feature bit") and became
> __UNUSED_NETIF_F_1. It's not used anywhere in the code.
> Remove this bit waste.
>
> It wasn't needed to rename the flag instead of removing it as
> netdev features are not uAPI/ABI. Ethtool passes their names
> and values separately with no fixed positions and the userspace
> Ethtool code doesn't have any hardcoded feature names/bits, so
> that new Ethtool will work on older kernels and vice versa.

This is only true for recent enough ethtool (>= 3.4)

You might refine the changelog to not claim this "was not needed".

Back in 2011 (and linux-2.6.39) , this was needed for sure.

I am not sure we have a documented requirement about ethtool versions.