Re: [RFC PATCH v2] ptp: Add vDSO-style vmclock support

David Woodhouse
2024-07-02T18:40:19Z

On 2 July 2024 19:12:00 BST, Peter Hilber <peter.hilber@opensynergy.com> wrote:
>On 02.07.24 18:39, David Woodhouse wrote:
>> To clarify then, the main types are
>>
>> VIRTIO_RTC_CLOCK_UTC == 0
>> VIRTIO_RTC_CLOCK_TAI == 1
>> VIRTIO_RTC_CLOCK_MONOTONIC == 2
>> VIRTIO_RTC_CLOCK_SMEARED_UTC == 3
>>
>> And the subtypes are *only* for the case of
>> VIRTIO_RTC_CLOCK_SMEARED_UTC. They include
>>
>> VIRTIO_RTC_SUBTYPE_STRICT
>> VIRTIO_RTC_SUBTYPE_UNDEFINED /* or whatever you want to call it */
>> VIRTIO_RTC_SUBTYPE_SMEAR_NOON_LINEAR
>> VIRTIO_RTC_SUBTYPE_UTC_SLS /* if it's worth doing this one */
>>
>> Is that what we just agreed on?
>>
>>
>
>This is a misunderstanding. My idea was that the main types are
>
>> VIRTIO_RTC_CLOCK_UTC == 0
>> VIRTIO_RTC_CLOCK_TAI == 1
>> VIRTIO_RTC_CLOCK_MONOTONIC == 2
>> VIRTIO_RTC_CLOCK_SMEARED_UTC == 3
>
>VIRTIO_RTC_CLOCK_MAYBE_SMEARED_UTC == 4
>
>The subtypes would be (1st for clocks other than
>VIRTIO_RTC_CLOCK_SMEARED_UTC, 2nd to last for
>VIRTIO_RTC_CLOCK_SMEARED_UTC):
>
>#define VIRTIO_RTC_SUBTYPE_STRICT 0
>#define VIRTIO_RTC_SUBTYPE_SMEAR_NOON_LINEAR 1
>#define VIRTIO_RTC_SUBTYPE_SMEAR_UTC_SLS 2
>

Thanks. I really do think that from the guest point of view there's really no distinction between "maybe smeared" and "undefined smearing", and have a preference for using the latter form, which is the key difference there?

Again though, not a hill for me to die on.