We can make the phc2sys helper not only synchronize a PHC to
CLOCK_REALTIME, which is what it currently does, but also CLOCK_REALTIME
to a PHC, which is going to be needed in distributed TSN tests.
Instead of making the complexity of the arguments passed to
phc2sys_start() explode, we can let it figure out the sync direction
automatically, based on ptp4l's port states.
Towards that goal, pass just the path to the desired ptp4l instance's
UNIX domain socket, and remove the $if_name argument (from which it
derives the PHC). Also adapt the one caller from the ocelot psfp.sh
test. In the case of psfp.sh, phc2sys_start is able to properly figure
out that CLOCK_REALTIME is the source clock and swp1's PHC is the
destination, because of the way in which ptp4l_start for the
UDS_ADDRESS_SWP1 was called: with slave_only=false, so it will always
win the BMCA and always become the sync master between itself and $h1.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Motivation
==========
One of the nice things about network namespaces is that they allow one
to easily create and test complex environments.
Unfortunately, these namespaces can not be used with actual switching
ASICs, as their ports can not be migrated to other network namespaces
(NETIF_F_NETNS_LOCAL) and most of them probably do not support the
L1-separation provided by namespaces.
However, a similar kind of flexibility can be achieved by using VRFs and
by looping the switch ports together. For example:
br0
+
vrf-h1 | vrf-h2
+ +---+----+ +
| | | |
192.0.2.1/24 + + + + 192.0.2.2/24
swp1 swp2 swp3 swp4
+ + + +
| | | |
+--------+ +--------+
The VRFs act as lightweight namespaces representing hosts connected to
the switch.
This approach for testing switch ASICs has several advantages over the
traditional method that requires multiple physical machines, to name a
few:
1. Only the device under test (DUT) is being tested without noise from
other system.
2. Ability to easily provision complex topologies. Testing bridging
between 4-ports LAGs or 8-way ECMP requires many physical links that are
not always available. With the VRF-based approach one merely needs to
loopback more ports.
These tests are written with switch ASICs in mind, but they can be run
on any Linux box using veth pairs to emulate physical loopbacks.
Guidelines for Writing Tests
============================
o Where possible, reuse an existing topology for different tests instead
of recreating the same topology.
o Tests that use anything but the most trivial topologies should include
an ASCII art showing the topology.
o Where possible, IPv6 and IPv4 addresses shall conform to RFC 3849 and
RFC 5737, respectively.
o Where possible, tests shall be written so that they can be reused by
multiple topologies and added to lib.sh.
o Checks shall be added to lib.sh for any external dependencies.
o Code shall be checked using ShellCheck [1] prior to submission.
1. https://www.shellcheck.net/
162d52dfee