[Query] ethtool cumbersome timestamping options

[Query] ethtool cumbersome timestamping options

[Russell King (Oracle)]

While spending some time with PTP stuff, specifically my Marvell PTP
library, and getting mv88e6xxx converted to it, etc, I was trying
out the timestamping related ethtool options:

        ethtool [ FLAGS ] -T|--show-time-stamping DEVNAME       Show time stamping capabilities
                [ index N qualifier precise|approx ]
        ethtool [ FLAGS ] --get-hwtimestamp-cfg DEVNAME Get selected hardware time stamping
        ethtool [ FLAGS ] --set-hwtimestamp-cfg DEVNAME Select hardware time stamping
                [ index N qualifier precise|approx ]

and I'm finding them particularly cumbersome and irritating to use.

Typing:

  ethtool -T eth0 index 0 qualifier precise

or

  ethtool -T eth0 index 1 qualifier precise

is quite annoying, especially when the man page states:

           qualifier precise|approx
                  Qualifier of the ptp hardware clock. Mainly "precise" the de‐
                  fault one is for IEEE 1588 quality and "approx" is  for  NICs
                  DMA point.

Note "the default one". That implies if it isn't given, this is what
will be used if it isn't specified, but this isn't so, you have to
type the whole "qualifier precise" thing out each and every time.
So, it isn't a default at all.

Either the man page needs to be fixed, or ethtool needs to actually
default to the value stated in the man page.

Alternatively, in this age of AI, I'd suggest changing the -- options
for timestamping to be:

ethtool --please-would-you-be-so-kind-as-to-change-the-timestamping-device-to
...

and

ethtool --please-show-me-the-current-timestamping-device-information

and similar, because with AI giving the commands to be executed, it
no longer matters how verbose command options are today. :D (I
suspect there will be some who will have a humour failure with that
suggestion...)

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

Re: [Query] ethtool cumbersome timestamping options

[Kory Maincent]

Hello Russell,

On Tue, 9 Sep 2025 16:40:55 +0100
"Russell King (Oracle)" <linux@armlinux.org.uk> wrote:

> While spending some time with PTP stuff, specifically my Marvell PTP
> library, and getting mv88e6xxx converted to it, etc, I was trying
> out the timestamping related ethtool options:
> 
>         ethtool [ FLAGS ] -T|--show-time-stamping DEVNAME       Show time
> stamping capabilities [ index N qualifier precise|approx ]
>         ethtool [ FLAGS ] --get-hwtimestamp-cfg DEVNAME Get selected hardware
> time stamping ethtool [ FLAGS ] --set-hwtimestamp-cfg DEVNAME Select hardware
> time stamping [ index N qualifier precise|approx ]
> 
> and I'm finding them particularly cumbersome and irritating to use.
> 
> Typing:
> 
>   ethtool -T eth0 index 0 qualifier precise
> 
> or
> 
>   ethtool -T eth0 index 1 qualifier precise
> 
> is quite annoying, especially when the man page states:
> 
>            qualifier precise|approx
>                   Qualifier of the ptp hardware clock. Mainly "precise" the
> de‐ fault one is for IEEE 1588 quality and "approx" is  for  NICs
>                   DMA point.
> 
> Note "the default one". That implies if it isn't given, this is what
> will be used if it isn't specified, but this isn't so, you have to
> type the whole "qualifier precise" thing out each and every time.
> So, it isn't a default at all.
> 
> Either the man page needs to be fixed, or ethtool needs to actually
> default to the value stated in the man page.

We could indeed set the precise qualifier as default and make the option
optional. 

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com