A VPCS node's single adapter anchors on a persistent TAP the server
creates (tap create + set_owner via uBridge) and the vpcs process
attaches to by name: -e -d <gp{id8}e0p0> -n, the same
server-creates/guest-attaches shape as QEMU's netdev. -n (a vpcs fork
feature) keeps the guest's ip command from ifconfig'ing the anchor on
the host; the vpcs build is probed once per binary identity
(vpcs_tap capability, usage scan) and gates kernel links together
with ubridge_tap — anything else keeps the node on the relay (the
legacy local UDP tunnel on a stock binary, an AF_PACKET endpoint on
the anchor with a capable one).
VPCSVM takes KernelDatapathMixin: _connect_nio dispatches kernel
(enslave into the per-link bridge) / relay-on-anchor / legacy,
captures pick capture start_kernel vs the bridge engine, stop runs
under an execute lock and terminates the process before deleting the
anchor TAPs (a held device refuses deletion), and the duplicate-port
guard backstops the controller's. The NIO routes accept nio_bridge
and write suspend back on update.
_delete_anchor_taps verifies each tap is gone from sysfs and retries
a bounded three times: a holder can release its fd a moment after its
process was reaped (vpcs's daemon parent kills its console child and
exits first), so the unconditional delete raced EBUSY and leaked the
anchor intermittently.
The vpcs side needs IFNAMSIZ (16) instead of its own IFNAMESIZ (12)
for the -d name buffer — anchor names are 14 chars and truncated to a
nonexistent device, which TUNSETIFF then tries to create without
CAP_NET_ADMIN (fixed in the vpcs fork).
e2e (tests/e2e/test_vpcs_kernel_datapath.py): kernel and relay
scenarios green against the real binary — real ICMP both ways, §E.1/§
E.2 on the anchors, delay/suspend/capture, link delete/re-create,
node stop/restart self-heal, zero leftovers; the relay control passes
with both the fork binary and a stock one.
Resolve conflicts against the upstream wave (PRs #2952-#2965, incl. the
typed-response/schema hardening and the drop of Python 3.10):
- controller/node.py: keep upstream's _transitioning/_confirm_status
lifecycle guard; the kernel-anchor link wiring (node_started) runs
after the transition completes.
- controller/link.py: keep upstream's add_node rollback (release_ports
on create failure) and delete via release_ports; release_ports now
resolves ports live (same staleness reason as _bind_members) and
discards the node link unconditionally.
- schemas/controller/links.py: extend LinkFilterType with the eight
kernel-datapath filter types and LinkFilterParameter.type with "str"
so the newly typed /available_filters response validates; Link.filters
stays a free-form dict — the vocabulary is capability-gated per link
and validated by the controller (409), not by a strict request schema.
- schemas/controller/topology.py: drop the type: ignore made redundant
by the dict filters field.
- tests: route-level filter validation now expects the controller's 409
(unknown types, out-of-range values); packet_loss correlation is a
valid kernel parameter (positive test added); OpenAPI assertions match
the free-form filters property.
