[systemd-devel] Ordering services issue. Trying to start ptp4l in bonding setup fails as bonding appears to take a while.

Wed Dec 1 14:20:10 UTC 2021

Hi,

I'm on embedded imx8 mm platform and trying to order services such that
ptp4l (LinuxPTP) is started after a bond is created between two DSA network
interfaces on my Microchip Ethernet Switch.

No matter what I try with BindsTo, Wants=, Requires=, Before=, After=, when
the board boots and I watch the console output I see systemd start the
ptp4l service before the bond is actually up which results in ptp4l failing
to start.

I've band-aided the issue by putting a Restart=yes and RestartSec=1 in the
service but feel like this is a hack.

As you can see below, the bond is in the process of coming up (you can see
enslaving messages regarding lan1 and lan2) but it is not all the way up
until after the login prompt ... at which point the service starting ptp4l
(the Sync Microchip PHC with PTP Grand Master  Clock msg) already failed.
>From timestamps it looks like it's taking 4 seconds or so for bond to come
up:

[  OK  ] Started Network Service.
        Starting Network Name Resolution...
[  OK  ] Started Rauc Good-marking Service.
[    4.098258] imx-sdma 302c0000.dma-controller: firmware found.
[    4.104259] imx-sdma 302c0000.dma-controller: loaded firmware 4.5
[  OK  ] Started Network Name Resolution[    4.135108] imx-sdma
302b0000.dma-controller: firmware found.
.
[  OK  ] Reached targe[    4.146220] imx-sdma 30bd0000.dma-controller:
firmware found.
t Network.
[  OK  ] Reached targe[    4.159060] caam-snvs 30370000.caam-snvs:
violation handlers armed - init state
t Network is Online.
[  OK  ] Reached target Host and Network Name Lookups.
        Starting Avahi mDNS/DNS-SD Stack...
        Starting Enable ksz9567...
        Starting The NGINX HTTP and reverse proxy server...
[  OK  ] Started Enable ksz9567.
[  OK  ] Started Avahi mDNS/DNS-SD Stack.
[  OK  ] Found device /sys/subsystem/net/devices/lan2.
[  OK  ] Started The NGINX HTTP and reverse proxy server.
[    4.390005] ksz9477-switch 0-005f lan2: configuring for phy/gmii link
mode
[    4.402902] bond1: (slave lan2): Enslaving as a backup interface with a
down link
[  OK  ] Found device [    4.544105] ksz9477-switch 0-005f lan1:
configuring for phy/gmii link mode
/sys/subsystem/net/devices/lan1.
[    4.555298] bond1: (slave lan1): Enslaving as a backup interface with a
down link
[  OK  ] Found device /sys/subsystem/net/devices/bond1.
        Starting Save/Restore Sound Card State...
[  OK  ] Started Save/Restore Sound Card State.
[  OK  ] Reached target Sound Card.
[    6.714002] random: crng init done
[    6.717436] random: 7 urandom warning(s) missed due to ratelimiting
[  OK  ] Started Load/Save Random Seed.
[  OK  ] Started System Logger Daemon "default" instance.
[  OK  ] Reached target Multi-User System.
        Starting Sync Microchip PH…with PTP Grand Master Clock...
        Starting Update UTMP about System Runlevel Changes...
[FAILED] Failed to start Sync Micro…C with PTP Grand Master Clock.
See 'systemctl status ptp4l.service' for details.
[  OK  ] Started Update UTMP about System Runlevel Changes.
[    7.659157] ksz9477-switch 0-005f lan1: Link is Up - 1Gbps/Full - flow
control rx/tx

Poky (Yocto Project Reference Distro) 3.1.7 imx8mmevk ttymxc1

imx8mmevk login: [    8.936988] bond1: (slave lan1): link status up,
enabling it in 0 ms
[    8.943510] bond1: (slave lan1): link status definitely up, 1000 Mbps
full duplex
[    8.951068] bond1: (slave lan1): making interface the new active one
[    8.962012] device eth0 entered promiscuous mode
[    8.966708] audit: type=1700 audit(1600598644.739:2): dev=eth0 prom=256
old_prom=0 auid=4294967295 uid=0 gid=0 ses=4294967295
[    8.966908] bond1: active interface up!
[    8.985999] IPv6: ADDRCONF(NETDEV_CHANGE): bond1: link becomes ready

My ptp4l.service looks like:

cat ptp4l.service
[Unit]
Description=Sync Microchip PHC with PTP Grand Master Clock
Requires=network-online.target multi-user.target
BindsTo=sys-subsystem-net-devices-bond1.device
sys-subsystem-net-devices-lan1.device sys-subsystem-net-devices-lan2.device
multi-user.target
After=sys-subsystem-net-devices-bond1.device
sys-subsystem-net-devices-lan1.device sys-subsystem-net-devices-lan2.device
multi-user.target

[Service]
Type=exec
#NotifyAccess=all
ExecStart=/usr/bin/ptp4l -f /etc/linuxptp/ptp4l.conf_e2e_one_step_g8275.2
-s -i bond1
Restart=on-failure
RestartSec=1

[Install]
WantedBy=multi-user.target

In my .network file I specify that bond1 is required to for being "online":

root at imx8mmevk:/etc/systemd/network# cat 10-bond1.network
[Match]
Name=bond1

[Network]
#BindCarrier=eth0
DHCP=yes
#Address=192.168.0.4/24

[Link]
RequiredForOnline=yes

In .system file I tried all I know to ensure the required interfaces were
created before starting ptp4l in attempt to give bonding enough time to
finish but binding to things like sys-subsystem-net-devices-bond1.device
wasn't enough.

Is it also possible to use carrier state in .service file?

I see sys/devices/virtual/net/bond1/carrier but not sure how to only
attempt to start my ptp4l service after carrier state is "1".

I welcome your ideas and suggestions on how to start a service after a bond
interface is really up.

Regards,

Brian
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