Hi!
On 2022. 05. 01. 13:29, Vladimir Oltean wrote:
The Felix VSC9959 switch in NXP LS1028A supports the tc-gate action which enforced time-based access control per stream. A stream as seen by this switch is identified by {MAC DA, VID}.
We use the standard forwarding selftest topology with 2 host interfaces and 2 switch interfaces. The host ports must require timestamping non-IP packets and supporting tc-etf offload, for isochron to work. The isochron program monitors network sync status (ptp4l, phc2sys) and deterministically transmits packets to the switch such that the tc-gate action either (a) always accepts them based on its schedule, or (b) always drops them.
I tried to keep as much of the logic that isn't specific to the NXP LS1028A in a new tsn_lib.sh, for future reuse. This covers synchronization using ptp4l and phc2sys, and isochron.
The cycle-time chosen for this selftest isn't particularly impressive (and the focus is the functionality of the switch), but I didn't really know what to do better, considering that it will mostly be run during debugging sessions, various kernel bloatware would be enabled, like lockdep, KASAN, etc, and we certainly can't run any races with those on.
I tried to look through the kselftest framework for other real time applications and didn't really find any, so I'm not sure how better to prepare the environment in case we want to go for a lower cycle time. At the moment, the only thing the selftest is ensuring is that dynamic frequency scaling is disabled on the CPU that isochron runs on. It would probably be useful to have a blacklist of kernel config options (checked through zcat /proc/config.gz) and some cyclictest scripts to run beforehand, but I saw none of those.
Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com
+switch_create() +{
- local h2_mac_addr=$(mac_get $h2)
- ip link set ${swp1} up
- ip link set ${swp2} up
- ip link add br0 type bridge vlan_filtering 1
- ip link set ${swp1} master br0
- ip link set ${swp2} master br0
- ip link set br0 up
- bridge vlan add dev ${swp2} vid ${STREAM_VID}
- bridge vlan add dev ${swp1} vid ${STREAM_VID}
- # PSFP on Ocelot requires the filter to also be added to the bridge
- # FDB, and not be removed
- bridge fdb add dev ${swp2} \
${h2_mac_addr} vlan ${STREAM_VID} static master- psfp_chain_create ${swp1}
- tc filter add dev ${swp1} ingress chain $(PSFP) pref 1 \
protocol 802.1Q flower skip_sw \dst_mac ${h2_mac_addr} vlan_id ${STREAM_VID} \action gate base-time 0.000000000 \sched-entry OPEN ${GATE_DURATION_NS} -1 -1 \sched-entry CLOSE ${GATE_DURATION_NS} -1 -1
I know that might be little bit off-topic here, but the current implementation of the act_gate does nothing with the IPV value [0] even if the user set it to non -1. IMO this IPV value should be carried through in the tcf_gate struct [1] as something like a "current_ipv" member or so. Then this value can be applied in the tcf_gate_act function to the skb->priority.
Background story: I tried to combine gate and taprio (802.1Qci and Qbv) to achieve 802.1Qch operation (which is really just a coordinated config of those two) but without the IPV (should by set by the ingress port) we have no way to carry the gating info to the taprio, and as a result its just sending every packet with the default priority, no matter how we open/close the gate at the ingress.
[0] https://elixir.bootlin.com/linux/v5.18-rc5/source/include/net/tc_act/tc_gate... [1] https://elixir.bootlin.com/linux/v5.18-rc5/source/include/net/tc_act/tc_gate... [2] https://elixir.bootlin.com/linux/v5.18-rc5/source/net/sched/act_gate.c#L117
+}
Ferenc