enumeratePci, addBars, pciConfigurationPtr, and the PciHeader struct are
deleted; the kernel seeds only the host bridge, and the ring-3 pci-bus
driver's reports are the sole source of PCI function nodes. The manager
matches PCI drivers from reported identity, deduped by registered device
id so a bus restart never double-spawns.
The flip did its job by exposing a latent SMP race: ring-3
device_register made the broker table concurrent for the first time, and
mmio_map read it lock-free — under load a torn resource length mapped
hpet's window wrong (its user fault) and underflowed r.len-1 into a
kernel integer-overflow panic. Fixed: the broker read in mmio_map (and
claim) runs under the big kernel lock, the arithmetic rejects
zero-length and wrapping windows cleanly, and pci-bus no longer registers
unimplemented size-0 BARs. driver-restart hammered 6x, suite 55/55.
Each function is registered under the bridge with the config-space slice
and BARs sized by the same all-ones probe the kernel uses — byte-for-byte
equal descriptors, so the idempotent register returns the kernel's
existing node ids during coexistence instead of duplicating the tree.
The bridge gained the 16-bit io_port aperture that functions' I/O BARs
need to pass containment. Reports carry the registered device_id, and
the pci-scan scenario drills a forced restart: kill the enumerator after
its reports, watch the respawn re-scan, and assert the broker's PCI node
count never grew. The usb-restart test trigger is pinned to the xHCI
reporter (pci-bus racing it to two reports used to steal the kill).
Harness hardening: failing cases preserve their serial logs; the heavy
scenarios run at 150s.
The manager matches the pci_host_bridge node and spawns pci-bus with the
bridge id as its assignment — hello, supervision, restart, all the M18
contract for free. The driver claims the bridge, maps the ECAM window
(resource 0) through the ordinary mmio grant, and repeats the kernel's
brute-force bus/device/function walk from user space. The pci-scan
scenario builds its expected marker from the kernel's own function count,
so the two enumerations must agree exactly — the equivalence that
licenses retiring the kernel walk in M19.3.
Daniel Samson