Bruce Simpson, Ph.D.PSA for people doing network #protocol development in 2026: If you bridge your laptop's #Ethernet port for #KVM guests to run in bridge mode, you can't use hardware timestamping directly for time synchronization, unless you run #IEEE #1588 in Annex F (Ethernet) mode. This applies to #chrony, #ptp4l and #ptpd equally. None of them know anything about bridged operation.
My only real indication of this was the lack of #linuxptp #ptp4l summary logging in #systemd's journalctl -f output, coupled with all the announce and delay timeouts at logging_level > 6; the #ThinkPad was NOT syncing AT ALL.
And it could not, by design, unless these #daemons can be persuaded to
"borrow" the bridge's assigned #IPv4 address on the physical #Ethernet port.
Dirk Wouters
