On Fri, 28 Nov 2025 20:38:28 +0000 Russell King (Oracle) wrote:

On Fri, Nov 28, 2025 at 09:16:24PM +0100, Andrew Lunn wrote:

quoted

quoted

Can you please tell me what is preventing us from deprecating pauseparam
API *for autoneg* and using linkmodes which are completely unambiguous.  

Just to make sure i understand you here...

You mean make use of

        ETHTOOL_LINK_MODE_Pause_BIT             = 13,
        ETHTOOL_LINK_MODE_Asym_Pause_BIT        = 14,

So i would do a ksettings_set() with

__ETHTOOL_LINK_MODE_LEGACY_MASK(Pause) | __ETHTOOL_LINK_MODE_LEGACY_MASK(Asym_Pause)

to indicate both pause and asym pause should be advertised.

The man page for ethtool does not indicate you can do this. It does
have a list of link mode bits you can pass via the advertise option to
ethtool -s, bit they are all actual link modes, not features like TP,
AUI, BNC, Pause, Backplane, FEC none, FEC baser, etc.  

I see the latest ethtool now supports -s ethX advertise MODE on|off,
but it doesn't describe that in the parameter entry for "advertise"
and doesn't suggest what MODE should be, nor how to specify multiple
modes that one may wish to turn on/off. I'm guessing this is what you're
referring to.

The ports never get advertised, so I don't think they're relevant.

However, the lack of the pause bits means that one is forced to use
the hex number, and I don't deem that to be a user interface. That's
a programmers interface, or rather a nightmare, because even if you're
a programmer, you still end up looking at include/uapi/linux/ethtool.h
and doing the maths to work out the hex number to pass, and then you
mistype it with the wrong number of zeros, so you try again, and
eventually you get the advertisement you wanted.

So no, I don't accept Jakub's argument right now. Forcing people into
the nightmare of working out a hex number isn't something for users.

I did some digging, too, just now. Looks like the options are indeed
not documented in the man page but ethtool uses the "forward compatible"
scheme with strings coming from the kernel. So this:

  ethtool -s enp0s13f0u1u1 advertise Pause on Asym_Pause on

works just fine, with no changes in CLI.

We should probably document that it works in the ethtool help and man
page. And possibly add some synthetic options like Receive-Only /
Transmit-Only so that users don't have to be aware of the encoding
details? Let me know if it's impractical, otherwise I think we'll
agree that having ethtool that makes it obvious how to achieve the
desired configuration beats best long form docs in the kernel..