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Re: [Ntp] CLOCK_TAI (was NTPv5: big picture)

Philip Prindeville <philipp@redfish-solutions.com> Tue, 05 January 2021 18:05 UTC

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From: Philip Prindeville <philipp@redfish-solutions.com>
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Date: Tue, 05 Jan 2021 11:05:23 -0700
Cc: NTP WG <ntp@ietf.org>, Warner Losh <imp@bsdimp.com>
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To: Magnus Danielson <magnus@rubidium.se>
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Subject: Re: [Ntp] CLOCK_TAI (was NTPv5: big picture)
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> On Jan 5, 2021, at 4:04 AM, Magnus Danielson <magnus@rubidium.se> wrote:
> 
> The particular thread started out with an ambition to steer how kernel
> implement things, that I think is outside the scope of the WG. What is
> inside is that regardless of how it is implemented, the needed
> definitions, information and similar is provided such that
> implementations (the notion kernel and user space may actually be
> completely irrelevant in some implementations) can reasonably be
> implemented, both in clarity and consistency.


I don’t agree.

It’s completely acceptable for the WG to mandate certain requirements like “must have RTC”, “RTC must be accurate to <= 16 ppm”, “must have persistent storage for storing […]”, etc.  Look at RFC-1122, 1123, and 1812…

Such a requirement was that the sysUpTime in MIB2 required a 100Hz (or better) clock.

There’s a reason that CONFIG_HZ_60 has long since disappeared from the Linux kernel sources.

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