Bug#1036744: PTP in combination with vclocks partially broken on Debian kernels
Package: linux-image-amd64
Version: 6.1.27-1
Hi all,
we did some investigations regarding time synchronization on Debian.
Background is industrial communication on Linux in general.
We found out that the PTP subsystem is only partially usable in
combination with virtual clocks on Debian. While the setup was running
fine on other distributions (like Ubuntu and Fedora) we had problems to
bring it up and running on Debian.
When starting ptp4l in combination with a vclock, the vclock could be
created but not attached to a physical clock:
ptp4l[127.805]: selected /dev/ptp4 as PTP clock
ptp4l[127.805]: port 1 (enptp): PHC device mismatch
ptp4l[127.805]: port 1 (enptp): /dev/ptp4 requested, ptp0 attached
ptp4l[127.805]: failed to open port enptp
failed to create a clock
It turned out that CONFIG_PTP_1588_CLOCK makes the difference. When
enabled (built-in, =y) our setup works, when set to "m" we run into
problems. The "problematic" code can be found at [1].
Might I request to set CONFIG_PTP_1588_CLOCK to y in the Debian kernel
configuration?
It would be possible that we provide a merge request on
salsa.debian.org. Just tell me the correct target branch. We would be
very happy to have it in 6.1 (bookworm) and of course in all kernel
flavors/feature sets.
Best regards,
Florian
[1]
https://elixir.bootlin.com/linux/v6.1.27/source/drivers/ptp/ptp_vclock.c#L232
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