QEMU's process monitor calls stop() by itself when the process dies, so an
API stop and a process-death stop run concurrently in the normal case — and
the datapath release sat outside _execute_lock, letting both stops sweep the
adapter TAP map at the same time. Whichever finished first cleared
_kernel_taps under the other's iterator, which died with "dictionary changed
size during iteration" (the monitor's task, so it surfaced as "Task exception
was never retrieved") with the rest of its sweep, the orphan-bridge removal
and uBridge's shutdown skipped.
Keep the previous fix's ordering (process side first, then the devices) and
hold the lock across the release: serialized, the second stop finds uBridge
gone and sweeps nothing. Reproduced deterministically with two concurrent
stop() calls, the first parked mid-sweep — it raised at qemu_vm.py:1659
before the change, and every TAP is swept exactly once after it.
QEMU is the guest side of every adapter TAP, and uBridge's tap delete
refuses a device another process holds open ('Device or resource busy') —
a best-effort delete whose failure is suppressed. QEMU's stop did the
delete first and stopped the process after, so every node stop or project
delete leaked the persistent TAPs: found by inspecting the host after a
project delete (16 taps left behind, carrier down, no holder), and the
held-tap behaviour reproduced against uBridge directly.
Stop the QEMU process first, then remove the TAPs and the per-link kernel
bridges — process side first, then the devices, the same lesson as IOU's
reverse stop order. Verified live: node stop and project delete now leave
no taps and no processes behind, while a restart recreates the TAPs.
The adapter anchor naming also goes through the shared
utils.kernel_anchor helper, like the other node types.
_console_options() fell through the "none" branch and returned None, so
_build_command() blew up on `command.extend(None)`: a QEMU node with
console_type "none" -- offered by the GUI, and what API/MCP-driven labs use
to skip the console entirely -- failed to start with a 500 and a traceback.
Return an empty list, exactly like _aux_options() already does, and cover it
with a test that builds the command line for a headless node. Verified on a
live instance: such a node now starts (204) with `console: null` and no
-serial device in the QEMU command line.
QEMU had no host-side interface at all: every adapter was a local UDP tunnel
into uBridge (-netdev socket plus two UDP ports per adapter), so a link could
only ever be a userspace relay. Each adapter now owns a persistent TAP
(gq{node_id[:8]}e{adapter}p{port}), created by uBridge before QEMU is launched
and handed to this user, and the netdev is that TAP -- the anchor role Docker's
veth host end plays. Links attach to it:
* kernel link (NIOBridge): brctl create/up/addif enslaves the TAP into the
per-link bridge and capture, markers and tc filters are installed on it,
verbatim through the shared KernelDatapathMixin -- a TAP and a veth host end
are interchangeable there (an egress qdisc on either impairs traffic entering
the node, and PACKET_OUTGOING on either is the node receiving);
* relay link: bridge add_nio_ethernet plus add_nio_udp -- AF_PACKET, never the
TAP NIO, which would take the fd QEMU itself holds.
The netdev type is fixed at launch, so this is all-or-nothing per VM: on the
TAP datapath every link type attaches to (or detaches from) a running VM,
including switching a link between the two datapaths. Stop un-persists the
TAPs (QEMU's open fd keeps each device alive until it exits) and removes the
per-link bridges; start sweeps leftovers first. A uBridge without the tap
module keeps the previous socket-netdev datapath, so an unupgraded install is
unaffected -- such a node simply cannot carry kernel links.
When a hostname validation fails, the error message now includes
the allowed character set to help users provide valid names.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* Offset pci_device_id for network devices by 32 (formerly 4)
to reserve first 32 IDs for non-netdev devices
* This implies a new pci_bridge for the netdevs and
the pci_device_ids starting at 0 (using modulo)
* Fixes a bug in the creation of the qemu command
when the number of qemu pcie devices (storage_controller, disks, …)
was greater than 4 and the number of network devices
saturated the 32 pcie ids of the root bridge
causing qemu not to start.
