net: ignore Intel's default unprogrammed MAC on igc NICs - #6991
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Some Intel i225 (NVM >= 1.53) and all i226 NICs ship with an unprogrammed placeholder MAC (00:a0:c9:00:00:00) until manufacturing flashes a real one. When two such NICs are present, cloud-init crashed with "duplicate mac found!" during networking setup. Rather than ignoring all duplicate MACs for the igc driver (which would also hide genuine duplicate-MAC hardware faults on this common NIC), filter out this specific known placeholder value the same way the existing all-zero MAC placeholder is already filtered. LP: #2142651 Fixes canonicalGH-6782
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Some Intel i225 (NVM >= 1.53) and all i226 NICs ship with an unprogrammed placeholder MAC (00:a0:c9:00:00:00) until manufacturing flashes a real one. When two such NICs are present, cloud-init crashed with "duplicate mac found!" during networking setup.
Rather than ignoring all duplicate MACs for the igc driver (which would also hide genuine duplicate-MAC hardware faults on this common NIC), filter out this specific known placeholder value the same way the existing all-zero MAC placeholder is already filtered. Fixes GH-6782.
There was a prior attempt at this in #6784, which added
igcto the existing driver-based duplicate-MAC ignore list (alongsidefsl_enetc,mscc_felix,qmi_wwan). That approach is broader than needed here:those other drivers are niche (automotive switches, cellular modems), but
igcbacks common consumer/server NICs (Intel I225/I226), so blanket-ignoring duplicate MACs for that driver would also silently hide a genuine duplicate-MAC hardware fault on such a board, rather than surfacing it as the RuntimeError does today. #6784 also had no test coverage and went stale.Per Intel's own documentation, I225 (NVM >= 1.53) and all I226 parts ship with a specific, known default/placeholder MAC (
00:a0:c9:00:00:00) until the manufacturing line programs a real one, this is exactly the MAC address in the linked bug report. This PR instead filters that specific sentinel value, the same wayget_interfaces()already filters the all-zero MAC placeholder as "no real per-device MAC assigned yet." Real, distinct MACs that happen to collide on igc NICs still raiseRuntimeErroras before.Test Steps
Added unit tests:
test_skip_intel_unprogrammed_placeholder_mac: two igc interfaces sharing the Intel placeholder MAC no longer raise, and are excluded fromget_interfaces_by_mac().test_real_duplicate_igc_macs_still_raise: two igc interfaces sharing a real (non-placeholder) MAC still raiseRuntimeError.tox -e py3 -- tests/unittests/test_net.pypasses (273 passed, 12 xfailed).