As of upstream kernel v4.18-rc8.
Note that we name the features like they are called in ethtool's
ioctl API ETH_SS_FEATURES.
Except, for features like "tx-gro", which ethtool utility aliases
as "gro". So, for those features where ethtool has a built-in,
alternative name, we prefer the alias.
And again, note that a few aliases of ethtool utility ("sg", "tso", "tx")
actually affect more than one underlying kernel feature.
Note that 3 kernel features which are announced via ETH_SS_FEATURES are
explicitly exluded because kernel marks them as "never_changed":
#define NETIF_F_NEVER_CHANGE (NETIF_F_VLAN_CHALLENGED | \
NETIF_F_LLTX | NETIF_F_NETNS_LOCAL)
Also, add two more features "tx-tcp-segmentation" and
"tx-tcp6-segmentation". There are two reasons for that:
- systemd-networkd supports setting these two features,
so lets support them too (apparently they are important
enough for networkd).
- these two features are already implicitly covered by "tso".
Like for the "ethtool" program, "tso" is an alias for several
actual features. By adding two features that are already
also covered by an alias (which sets multiple kernel names
at once), we showcase how aliases for the same feature can
coexist. In particular, note how setting
"tso on tx-tcp6-segmentation off" will behave as one would
expect: all 4 tso features covered by the alias are enabled,
except that particular one.
Note that in NetworkManager API (D-Bus, libnm, and nmcli),
the features are called "feature-xyz". The "feature-" prefix
is used, because NMSettingEthtool possibly will gain support
for options that are not only -K|--offload|--features, for
example -C|--coalesce.
The "xzy" suffix is either how ethtool utility calls the feature
("tso", "rx"). Or, if ethtool utility specifies no alias for that
feature, it's the name from kernel's ETH_SS_FEATURES ("tx-tcp6-segmentation").
If possible, we prefer ethtool utility's naming.
Also note, how the features "feature-sg", "feature-tso", and
"feature-tx" actually refer to multiple underlying kernel features
at once. This too follows what ethtool utility does.
The functionality is not yet implemented server-side.
