Thread (9 messages) 9 messages, 4 authors, 2024-10-28

Re: [PATCH net-next v7] ptp: Add support for the AMZNC10C 'vmclock' device

From: Jakub Kicinski <kuba@kernel.org>
Date: 2024-10-28 16:12:59
Also in: linux-arm-kernel, linux-rtc, lkml, qemu-devel, virtualization

On Sat, 19 Oct 2024 18:49:24 +0100 David Woodhouse wrote:
quoted
Yes please and thank you! We gotta straighten it out before 
the merge window.  
Hm, as I (finally) come to do that, I realise that many of the others
defined in drivers/ptp/Kconfig are also 'default y'. Which is only
really 'default PTP_1588_CLOCK' in practice since they all depend on
that.
AFAICT nothing defaulted to enabled since 2017, so I'd chalk it up
to us getting better at catching mistakes over time.
Most importantly, PTP_1588_CLOCK_KVM is 'default y'. And that one is
fundamentally broken (at least in the presence of live migration if
guests care about their clock suddenly being wrong) which is why it's
being superseded by the new VMCLOCK thing. We absolutely don't want to
leave the _KVM one enabled by default and not its _VMCLOCK replacement.
You can default to .._CLOCK_KVM, and provide the explanation in
the commit message and Kconfig help.
Or if you feel strongly even make CLOCK_KVM depend on the new one?
Please advise... I suspect the best answer is to leave it as it is? 
I'd really rather not. Linus has complained to us about Kconfig symbols
appearing / getting enabled by default multiple times in the past.

Sorry for the delay, vacation time.
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