linux-kernel - Re: [PATCH v9 12/13] rust: hrtimer: add clocksource selection through `ClockSource`

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Message-ID: <87eczjeo5i.ffs@tglx>
Date: Thu, 27 Feb 2025 10:24:09 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Andreas Hindborg <a.hindborg@...nel.org>, Miguel Ojeda
 <ojeda@...nel.org>, Anna-Maria Behnsen <anna-maria@...utronix.de>,
 Frederic Weisbecker <frederic@...nel.org>, Danilo Krummrich
 <dakr@...nel.org>
Cc: Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>,
 Gary Guo <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>,
 Benno Lossin <benno.lossin@...ton.me>, Alice Ryhl <aliceryhl@...gle.com>,
 Trevor Gross <tmgross@...ch.edu>, Lyude Paul <lyude@...hat.com>, Guangbo
 Cui <2407018371@...com>, Dirk Behme <dirk.behme@...il.com>, Daniel Almeida
 <daniel.almeida@...labora.com>, Tamir Duberstein <tamird@...il.com>,
 rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, Andreas
 Hindborg <a.hindborg@...nel.org>
Subject: Re: [PATCH v9 12/13] rust: hrtimer: add clocksource selection
 through `ClockSource`

On Thu, Feb 27 2025 at 10:11, Thomas Gleixner wrote:
> On Mon, Feb 24 2025 at 13:03, Andreas Hindborg wrote:
>> +    /// International Atomic Time.
>> +    ///
>> +    /// A nonsettable system-wide clock derived from wall-clock time but
>> +    /// counting leap seconds. This clock does not experience discontinuities or
>> +    /// frequency adjustments caused by inserting leap seconds as CLOCK_REALTIME
>> +    /// does.
>
> Only partially correct.
>
> CLOCK_TAI can be set as CLOCK_TAI is obviously coupled to CLOCK_REALTIME
> and vice versa.

For clarification:

    CLOCK_REALTIME (UTC) = CLOCK_TAI - sum(leap seconds since the epoch)

As of today thats 37 seconds.

Thanks,

        tglx