ethtool cumbersome timestamping options
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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.
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Hello Russell,
Quoted 27 lines · On Tue, 9 Sep 2025 16:40:55 +0100 "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.
Quoted 7 lines
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,
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Köry Maincent, Bootlin Embedded Linux and kernel engineering https://bootlin.com