# Re: \[PATCH 18/24\] timekeeping: Prepare for cross timestamps on arbitrary clock IDs

- From: David Woodhouse \<dwmw2@infradead.org\>
- Date: 2026-05-26 23:54:32 
- List: netdev
- Page: https://ratatoskr.run/netdev/2026/05/17033773
- Thread: https://ratatoskr.run/kvmarm/2026/05/17032577/t.md

```text
On Tue, 26 May 2026 19:14:57 +0200, Thomas Gleixner wrote:
> PTP device system crosstime stamps support only CLOCK_REALTIME, which is
> meaningless for AUX clocks. The PTP core hands in the clock ID already, so
> prepare the core code to honor it.
>
>  - Add a new sys_systime field to struct system_device_crosststamp which
>    aliases the sys_realtime field. Once all users are converted
>    sys_realtime can be removed.
>
>  - Prepare get_device_system_crosststamp() and the related code for it by
>    switching to sys_systime and providing the initial changes to utilize
>    different time keepers.
>
> No functional change intended.
>
> Signed-off-by: Thomas Gleixner <tglx@kernel.org>

I suspect I'll be back to frown at adjust_historical_crosststamp() at
some point, but that's a separate issue. For this change:

Reviewed-by: David Woodhouse <redacted>
Tested-by: David Woodhouse <redacted>

```

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