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bef68e201e
Setting the IPv6 address generation mode of a net device during its creation never worked, but after commitb0ad3c1790("rtnetlink: call validate_linkmsg in rtnl_create_link") it explicitly fails [1]. The failure is caused by the fact that validate_linkmsg() is called before the net device is registered, when it still does not have an 'inet6_dev'. Likewise, raising the net device before setting the address generation mode is meaningless, because by the time the mode is set, the address has already been generated. Therefore, fix the test to first create the net device, then set its IPv6 address generation mode and finally bring it up. [1] # ip link add name mydev addrgenmode eui64 type dummy RTNETLINK answers: Address family not supported by protocol Fixes:ba95e79309("selftests: forwarding: hw_stats_l3: Add a new test") Signed-off-by: Danielle Ratson <danieller@nvidia.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: Petr Machata <petrm@nvidia.com> Link: https://lore.kernel.org/r/f3b05d85b2bc0c3d6168fe8f7207c6c8365703db.1686580046.git.petrm@nvidia.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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/