Re: ixgbe: How to do this without a module parameter?

Robert Schlabbach [off-list ref] writes:

A while ago, Intel devs sneaked a hack into the ixgbe driver which disables
NBASE-T support by default:

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c?id=a296d665eae1e8ec6445683bfb999c884058426a

Only after a user complaint, Intel bothered to reveal their reason for this:

https://www.mail-archive.com/e1000-devel@lists.sourceforge.net/msg12615.html

But this comes at the expense of NBASE-T users, who are left wondering why their
NIC (which Intel sells as supporting NBASE-T) only comes up with GbE links. To
fix this, I submitted this patch:

https://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20211018/026326.html

However, Intel devs pointed out to me that private module parameters would no
longer be accepted. Indeed, after some search I found this in the archive:

https://lore.kernel.org/netdev/20170324.144017.1545614773504954414.davem@davemloft.net/ (local)

The reason given there is that a module parameter is the "worst user experience
possible". But I think the absolutely worst user experience possible is having
to figure out a complex script that:

- compiles a list of all net devices provided by the ixgbe module
- retrieves the supported link speeds and converts them to a hex mask
- ORs the NBASE-T speeds into this hex mask
- finally runs ethtool to set the hex mask of the speeds to advertise

Even as a developer with 10 years experience with Linux, I would have to spend
quite a while writing such a script, and then figuring out how to have it
executed at the right time during startup. I suppose the vast majority of
Linux admins would be overwhelmed with that.

In contrast, explaining how to set the module parameter to control NBASE-T
support is a two-liner, see my patch above where I added that to the ixgbe.rst
module documentation. I think that's feasible for most Linux admins.

So my question is: Can anyone come up with a solution allowing to control
NBASE-T support in the ixgbe module in a way that's feasible for most Linux
admins, that works without a module parameter?

If not, could an exception be made for this patch to allow an extra parameter
for the ixgbe module?

Or does anyone have an even better idea?

If it can be set with ethtool already, and the issue is mostly the
user-friendliness of this interface, how about teaching ethtool a
symbolic parameter to do this for you? E.g. something equivalent to:

'ethtool --change eth0 advertise +nbase-t' ?

Personally I wouldn't mind having this (symbolic names) for all the
supported advertised modes; I also think it's a pain to have to go
lookup the bit values whenever I need to change this...

-Toke