On Fri, 29 Mar 2024 16:56:12 +0800 Heng Qi wrote:

quoted

About the uAPI - please make sure you add the new stuff to
Documentation/netlink/specs/ethtool.yaml
see: https://docs.kernel.org/next/userspace-api/netlink/specs.html

And break up the attributes, please, no raw C structs of this nature:

+	return nla_put(skb, attr_type, sizeof(struct dim_cq_moder) *
+		       NET_DIM_PARAMS_NUM_PROFILES, profs);

They are hard to extend.  

Sorry, I don't seem to get your point, why does this make extending hard?

It's not possible to make some fields optional later on.
It's also possible that user space will make assumptions about the size
of this struct so we won't be able to add fields.

So it's preferred to render the C struct members as individual netlink 
attributes. Look around ethtool netlink, you'll see there are no
structs dumped.

Are you referring to specifying ETHTOOL_A_COALESCE_RX_EQE_PROFILE
as a nested array, i.e. having each element explicitly have an attr 
name? or passing the u16 pointer and length as arguments?