RedBear-OS/local/docs/DRIVER-MANAGER.md

Red Bear OS — driver-manager

Canonical planning and current-state document (single source of truth). Consolidates and supersedes the historical v1.0 → v5.9 migration plan.

Generated: 2026-07-27 (post-v5.9 systematic assessment) Last updated: 2026-07-27 (F1/F2/F3/F5/F6a/F6b/F6c/F6d fixes landed; status table updated) Scope: viability, correctness, completeness, edge cases, gaps, bugs, blockers, and the actionable fix/improvement plan. Toolchain: Rust nightly-2026-05-24 (edition 2024) Cross-reference baseline: Linux kernel 7.1 (local/reference/linux-7.1/ at ab9de95c9), CachyOS (local/reference/cachyos/).

Historical material: the v1.0 → v5.9 migration plan is archived at local/docs/archived/DRIVER-MANAGER-MIGRATION-PLAN.md. Read this doc for current state; read the archive for the round-by-round history.

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1. Status — viability

1.1 Executive verdict

driver-manager is viable and operationally the sole PCI driver match/claim/spawn owner in Red Bear OS as of the 2026-07-24 operator-ratified cutover. pcid-spawner is fully retired (crate removed, service files removed, configs and build wiring cleaned); source is preserved in git history. Init learned systemd-style ConditionPathExists (with ! negation) so the driver-manager path is unconditional and the dormant pcid-spawner fallback (operator A/B comparison only) is gated by /etc/driver-manager.d/disabled.

Cutover QEMU runtime gate: PASSED (commit 78665ede70, 2026-07-23). Evidence: q35 topology, initfs driver-manager claims ahcid (bound: 0000--00--1f.2 -> ahcid), switchroot proceeds, rootfs driver-manager claims e1000d concurrently (bound: 0000--00--02.0 -> e1000d, zero deferred), scheme:driver-manager registers, resident hotplug loop starts. The dormant 00_pcid-spawner.service is skipped via ConditionPathExists on both initfs and rootfs.

Compile posture: driver-manager + cpufreqd + pcid compile clean (zero crate-local warnings) on host and on the x86_64-unknown-redox target. Cookbook content-hash cache tracks Cargo path = dep source trees, closing the staleness hole that previously let redox-driver-core source changes stay cached in driver-manager.

Test posture: 112 host tests (driver-manager 88 + cpufreqd 21 + 3 contract tests) all pass; 3 E2E integration tests in end_to_end_test.rs; 8 QEMU blackbox test scripts in local/scripts/; 1 audit gate (driver-manager-audit-no-stubs.py) reporting 0 violations across 35+ files.

1.2 What's genuinely good (do not regress)

• D-phase skeleton maps cleanly onto Linux 7.1: DeviceManager + dynids + deferred-probe + policy + quirks. Where Red Bear deviates (per-device IRQ-mode env, TOML + DMI quirks, priority field) the deviations are defensible or strictly superior.
• pcid + pcid_interface are production-quality — the channel-exclusivity claim model (ENOLCK) and the env-hint consumer chain (REDBEAR_DRIVER_PCI_IRQ_MODE, REDBEAR_DRIVER_DISABLE_ACCEL, REDBEAR_DRIVER_IOMMU_GROUP, REDBEAR_DRIVER_NUMA_NODE, REDBEAR_DRIVER_MSIX_VECTORS) are end-to-end real.
• Claim model collapses correctly (P0-1 closed, 2026-07-23): a single PciFunctionHandle::connect_by_path() → ENOLCK → next candidate → into_inner_fd() → PCID_CLIENT_CHANNEL to child. Claim lifetime == child lifetime == channel fd lifetime. No redundant /bind endpoint, no orphan patch in the tree.
• AER/pciehp producers exist (P2-1 closed, 2026-07-24): pcid 500ms poller reads PCIe AER extended-capability and Slot Status, emits W1C-cleared event lines at /scheme/pci/aer and /scheme/pci/pciehp. driver-manager's listener moved from the nonexistent /scheme/acpi/aer to the real producer path.
• AER dedup is monotonic-seq with persistent state (G-A1/G-A3/G-A5 closed at v5.0): restart does not replay recovery actions; /var/run/driver-manager/event-seqs.json survives driver-manager restart.
• Adjacent tech actually works: cpufreqd registers a real cpufreq scheme (G-A2 closed at v5.1); redbear-iwlwifi --daemon honors PCID_CLIENT_CHANNEL via PciFunctionHandle::connect_default() (G-A4 closed at v5.2); Mesa CS submit seqno is kernel-assigned and multi-process correct (v5.4); initnsmgr has kernel O_NONBLOCK OpenAt and bounded pending-queue (v5.3 / Design B).

1.3 What is NOT yet proven

• Hardware validation matrix (D5 ratification gate). Operator-only work: AMD Threadripper (canonical AMD profile) + Intel Alder Lake or later with ≥3 driver categories each (storage, network, USB, GPU). local/docs/HARDWARE-VALIDATION-MATRIX.md tracks the matrix.
• Two-week soak + three bare-metal reboots (C4 ratification gate). Operator-only work.
• Real-hardware AER recovery outcomes. QEMU validates the dispatch path; only real AER injectors / firmware can validate that RecoveryAction::ResetDevice / RescanBus recover the device.

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2. Architecture

2.1 Crate layout

local/recipes/system/driver-manager/ (symlinked from recipes/system/driver-manager/). Pure Rust, edition 2024, version 0.1.0 (recipe) / 0.3.1 (Cargo.toml).

File	Lines	Role
main.rs	681	CLI, initfs/rootfs dispatch, deferred-retry loop
config.rs	1168	DriverConfig, probe, claim, spawn, Driver trait impl, dynid validation
scheme.rs	907	/scheme/driver-manager server (bind/unbind/new_id/remove_id/driver_override/rescan/recover/timing/modalias)
timing.rs	869	Boot-race instrumentation (claim-spawn / firmware-ready / governor-switch / aer-event buckets)
unified_events.rs	298	Multiplexed AER + pciehp + scheme events; persistent seq state
aer.rs	321	AER parse + severity→RecoveryAction routing + dispatch
pciehp.rs	235	PCIe hotplug parse (presence_detect / attention_button / mrl_sensor / dll_state)
policy.rs	277	Blacklist TOML parsing from /etc/driver-manager.d/*.toml, SIGHUP reload
quirks.rs	222	PciQuirkFlags → spawn-time env-var decisions
linux_loader.rs	388	Linux pci_device_id → TOML match conversion (--import-linux-ids)
error_channel.rs	346	REDBEAR_DRIVER_ERROR_FD sidecar IPC for Driver::on_error
heartbeat.rs	190	/var/run/driver-manager.heartbeat.json publisher
hotplug.rs	155	PCI hotplug polling diff (add/remove)
modalias.rs	139	MODALIAS string computation + lookup
reaper.rs	114	SIGCHLD child reaper
sighup.rs	63	SIGHUP → blacklist reload worker
registry.rs	28	Weak registry for reaper
end_to_end_test.rs	279	3 E2E tests (MockPciBus + MockDriver)
Total	~6,680	18 production modules + 1 E2E test module

2.2 Dependencies

redox-driver-core     local/recipes/drivers/redox-driver-core/    (DeviceManager, dynid, modern_technology)
redox-driver-pci      local/recipes/drivers/redox-driver-pci/     (PciBus, PciDevice)
redox-driver-sys      local/recipes/drivers/redox-driver-sys/     (PciQuirkFlags, scheme:memory, scheme:irq)
pcid_interface        local/sources/base/drivers/pcid/           (PciFunctionHandle, enable_feature, env hints)
redox-scheme          local/sources/redox-scheme/                (SchemeSync framework)
redox_syscall (syscall) local/sources/syscall/                   (O_NONBLOCK, O_RDWR, etc.)
log, toml, serde, libc (host crates)

All deps are path = deps; [patch.crates-io] covers the local forks for transitive resolution.

2.3 Boot sequence (concise)

bootloader → init → initfs phase
    ↓
    /etc/init.d/40_driver-manager-initfs.service  (oneshot, --initfs, transient)
    → reads /scheme/initfs/lib/drivers.d/*.toml
    → enumerates /scheme/pci (one-shot)
    → spawns ahcid/ided/nvmed/virtio-blkd for storage devices
    → exits (no scheme registration in initfs)
    ↓
    switchroot to redoxfs rootfs
    ↓
    /etc/init.d/00_driver-manager.service  (oneshot_async, --hotplug, resident)
    → reads /lib/drivers.d/*.toml
    → spawn+join concurrent worker pool (Arc semaphore; thread::scope banned — hangs on Redox)
    → spawns e1000d / xhcid / redox-drm / ihdad / etc.
    → registers /scheme/driver-manager
    → starts:
        - SIGCHLD reaper (100ms worker poll)
        - SIGHUP blacklist reload worker
        - Unified AER + pciehp + heartbeat thread (500ms poll)
        - Resident hotplug loop (250ms poll, `--hotplug` only)
    → survives for the life of the OS

2.4 The two PCI-claim systems

There is exactly one PCI-claim system in production: driver-manager's channel-exclusivity model. The linux-kpi PCI layer is only invoked inside a Linux-port daemon that driver-manager has spawned (it consumes the granted channel via PciFunctionHandle::connect_default() in spawned mode). linux-kpi's standalone pci_register_driver mode is for CLI tools only. pci_register_driver does not enumerate /scheme/pci when PCID_CLIENT_CHANNEL is in the environment — it matches only the granted device and calls probe for that one device. (See G-A2 closure in the archive: this was the v3.0 architectural finding; LDR-1 → LDR-5 fixed it.)

2.5 The scheme operator surface (/scheme/driver-manager)

Endpoint	Access	Purpose
/	read dir	List endpoints
/devices	read dir	List bound PCI BDFs
/devices/<bdf>	read	Show driver + enabled status
/bound	read	addr → driver map (consumed by udev-shim, driver-params, evdevd)
/events	read	Recent probe events (ring buffer, max 256)
/modalias	read / write	Linux MODALIAS lookup
/bind	write	Force-bind <driver> <pci_addr>
/unbind	write	Unbind <pci_addr>
/new_id	write	Add dynamic device ID
/remove_id	write	Remove dynamic device ID
/driver_override	write	Per-device driver_override (Tier-1 precedence)
/rescan	write	Re-enumerate all buses
/recover	write	Trigger AER recovery action
/timing	read	Boot-race instrumentation JSON snapshot

13 endpoints; runs on a separate thread (not the main probe thread).

2.6 Driver TOML format

Read from /lib/drivers.d/*.toml (rootfs) or /scheme/initfs/lib/drivers.d/*.toml (initfs). Two formats are supported; the modern [[driver]] form is preferred:

[[driver]]
name = "e1000d"
priority = 80
command = ["e1000d"]

[[driver.match]]
vendor = 0x8086
device = 0x100E
class = 0x02
subclass = 0x00

[[driver.match]]              # multiple match entries allowed
vendor = 0x8086
class = 0x02
subclass = 0x00

Legacy [[drivers]] form (with ids map + device_id_range) is auto-converted at load time. The matchless form (no [[driver.match]] subtable) is supported for USB-class drivers and is used by the auto-spawn path.

2.7 Comprehensive driver inventory

39 drivers across 8 categories. Every driver has a match-table entry or an auto-spawn path. Cross-checked against /lib/drivers.d/*.toml in v3.2.

Category	Drivers
PCI host bus	pcid (producer of /scheme/pci/*)
Storage	ahcid, nvmed, ided, virtio-blkd, usbscsid
Network	e1000d, rtl8168d, rtl8139d, ixgbed, virtio-netd, redbear-iwlwifi
USB HC	xhcid, ehcid, ohcid, uhcid
USB class	redbear-acmd, redbear-ecmd, redbear-usbaudiod, redbear-ftdi, redbear-btusb
Graphics	redox-drm (full only), amdgpu (FFI in-process), virtio-gpud (full only), ihdgd (legacy), vesad (legacy)
Input	ps2d, usbhidd, inputd, virtio-inputd
Audio	ihdad, ac97d, sb16d
Power / RTC / System	acpid, rtcd, hwd, redoxerd, vboxd

Open: ihdgd and vesad are marked "🟡 legacy" in the inventory table. They are still wired in base but no driver-manager match. They are init-managed services — verify on next base recipe sync that they are either removed or re-classified.

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3. Capability status — current truth

Linux 7.1 capability matrix (C1–C18). Status reflects post-v5.6 state. Three columns: Build = compiles + unit tests pass; QEMU = QEMU runtime gate passed; HW = hardware validation passed.

#	Capability	Build	QEMU	HW	Notes
C1	ID-table match + dynamic ID add	✅	✅	🔴	DeviceManager.register_driver() + match_table() + add_dynid(). dynid validation tested.
C2	Device lifecycle (probe/remove)	✅	✅	🔴	Driver::probe + Driver::remove. remove() sends SIGTERM (3s grace) → SIGKILL.
C3	Enable / disable device	✅	✅	🔴	enable_device() writes PCI command register via pcid.
C4	BAR request/release	✅	✅	🔴	Channel open = ENOLCK exclusivity (claim lifetime == child lifetime).
C5	BAR map/unmap	✅	✅	🔴	Child uses redox-driver-sys::PciDevice::map_bar.
C6	Bus master on/off	✅	✅	🔴	Bundled in enable_device via PCI command register layout.
C7	Allocate IRQ vectors	✅	✅	🔴	pcid_interface::enable_feature(PciFeature::Msi/MsiX).
C8	Resolve vector → IRQ	✅	✅	🔴	Child via scheme:irq per vector.
C9	Runtime PM	🟡	🟡	🔴	Trait exists; Driver::suspend/resume with RecoveryAction-like return; PM-state gate in spawn path NOT wired. G-fix-1 below.
C10	Save/restore config space	✅	✅	🔴	Child uses PcidClient::read_config/write_config.
C11	Driver override	✅	✅	🔴	Scheme endpoint /driver_override + Tier-1 precedence.
C12	Config space read/write	✅	✅	🔴	Child-side via PcidClient.
C13	AER error recovery	🟡	✅	🔴	4-state (Handled/ResetDevice/RescanBus/Fatal); Linux 7.1 uses 6-state (mmio_enabled/slot_reset/resume split). G-fix-2 below.
C14	Hotplug events	🟡	✅	🔴	4 of 5 hardware bits (presence_detect / attention_button / mrl_sensor / dll_state); power_fault missing on consumer side (pcid producer has it). G-fix-3 below.
C15	DMA mask / IOMMU	✅	✅	🔴	iommu_group_env_value returns "0" on absent scheme (honest, not stub).
C16	Find capabilities	✅	✅	🔴	Child-side via redox-driver-sys.
C17	INTx on/off	✅	✅	🔴	Child-side via PcidClient.
C18	System PM	🟡	🟡	🔴	Trait done; manager-mediated suspend sequence not wired (driver-by-driver recovery not ordered by priority). G-fix-4 below.

Tally: 14 ✅ Build + QEMU / 4 🟡 partial / 0 🔴 at the manager layer. All "🟡 partial" rows have trait/feature implementations but lack manager-side wiring. They are not stubs — they are documented gaps awaiting follow-up work.

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4. Systematic correctness review (2026-07-27)

This is the new content the assessment adds over the v5.9 plan. Findings are ordered severity-first.

4.1 New findings (post-v5.9)

F1 — No crash-driven restart, no backoff, no blacklist on repeated failure

Severity: 🟡 HIGH (runtime-correctness) Location: source/src/reaper.rs:22-72, source/src/config.rs:534-585 Description: The SIGCHLD reaper removes a dead child PID from the spawned: Mutex<HashMap<String, SpawnedDriver>> map. On the next probe cycle, spawned.contains_key() returns false and the manager re-spawns the driver. There is no crash counter, no backoff timer, no exponential delay, no blacklist after N failures. A driver that crashes on every startup (e.g. malformed config, missing firmware, broken BAR map) will be re-spawned every 250ms (hotplug loop poll interval) indefinitely. Each spawn consumes a process slot and clutters logs.

Evidence:

• reaper.rs:22-72 — reaper removes PID, no metric incremented.
• config.rs:534-542 — reap_pid() deletes from both maps, no failure counter.
• config.rs:577-585 — next probe sees empty map → re-spawns.

Fix: see § 5.1 F1.

F2 — .forget() on reaper JoinHandle leaks thread panic visibility

Severity: 🟡 MEDIUM (observability) Location: source/src/reaper.rs:1 (.expect("spawn sigchld reaper")) plus .forget(handle) on the JoinHandle Description: The reaper worker thread is spawned and its JoinHandle is intentionally .forget()-ed so the main thread can continue without blocking on it. If the reaper thread panics (e.g. on a poisoned mutex that the unwrap_or_else(|e| e.into_inner()) chain fails to recover), the daemon continues running without any indication that the reaper is dead. Crashed children stop being reaped; pid_to_device map grows without bound; eventually EAGAIN on fork() may surface.

Fix: see § 5.2 F2.

F3 — 30-retry deferred-probe cap silently abandons long-startup drivers

Severity: 🟡 MEDIUM (boot-time correctness) Location: source/src/main.rs:599-651 Description: After initial enumeration, driver-manager enters a deferred-retry loop that sleeps 500ms and calls mgr.retry_deferred() up to 30 times (15 seconds total wall-clock). After 30 retries, main() calls process::exit(0) if no drivers remain deferred. In the resident hotplug mode, the cap does not apply — the loop retries forever on each poll cycle — but in oneshot mode (the path that governs initfs boot ordering), a driver whose connect_by_path() returns ENOENT more than 30 times (e.g. firmware takes >15s to become ready, or a slow PCI device needs many retries to enumerate) is permanently deferred until the next manual enumeration.

The Linux analog (deferred-probe timeout) is configurable and surfaces a deferred_probe_timeout sysctl; here it is a hardcoded constant.

Fix: see § 5.3 F3.

F4 — Poll-only architecture is a performance ceiling, not a bug

Severity: 🟢 LOW (architectural — not blocking) Location: hotplug.rs:25 (250ms), unified_events.rs:98 (500ms), main.rs:599-651 (500ms), reaper.rs:22-72 (100ms) Description: driver-manager uses std::thread::sleep(Duration) polling for every event source. No epoll, no signalfd, no eventfd, no kernel-level event notification. On QEMU (q35, 6 devices) this is fine; on bare-metal AMD Threadripper with 30+ devices, the 250ms hotplug poll means a device-add → driver-spawn latency floor of ~250ms even when the kernel signals the event immediately.

Why not blocking: pcid producers are themselves pollers (500ms AER poller, 500ms pciehp poller), so reducing driver-manager's poll below 500ms gains nothing at the pcid layer. A real fix requires signalfd/eventfd in pcid (G-A3 follow-up: MSI-based AER delivery requires a pcid IRQ path).

Fix: see § 5.4 F4 (informational — tracked as a Phase-5 GPU item).

F5 — ConcurrentDeviceManager double-enumerates buses (P3 hygiene)

Severity: 🟢 LOW (correctness, latency) Location: redox-driver-core::manager.rs (per G8 in v3.0 assessment) Description: enumerate() is called by both the main probe path and ConcurrentDeviceManager::run_probe. Each call re-walks all registered buses. On QEMU (1–2 buses, <10 devices) this is invisible; on a real system with USB + PCI + virtio + platform buses, each concurrent probe cycle does 2× the enumeration work.

Fix: see § 5.5 F5.

F6 — Capability gaps C9 / C13 / C14 / C18 — partial, not stub

Severity: 🟢 LOW (correctness, completeness) Description: Four capabilities are "🟡 partial" because the trait or parser exists but manager-side wiring is incomplete. None are stubs — they are documented follow-ups with clear paths. See § 3 capability matrix for detail and § 5.6–§ 5.9 for the specific fixes.

4.2 Edge cases — verified correct

Scenario	Behavior	Status
Driver binary path is a symlink to a missing target	spawned.lock().unwrap_or_else(...) catches, probe returns Deferred with BinaryMissing reason	✅ correct
Initfs driver-manager runs in rootfs (EEXIST collision)	Initfs mode no longer registers the scheme (fixed v3.2); no collision	✅ correct
PCI device with multiple functions	Each function gets independent BDF; treated as independent device	✅ correct
Multiple drivers match same device	Priority-ordered; first-match-wins; exclusive_with raises priority collision	✅ correct
Spawned driver crashes between fork and first heartbeat	Reaper catches SIGCHLD, removes from spawned; next probe re-spawns (see F1 for the failure-mode concern)	⚠️ correct-but-noisy
/scheme/pci not registered yet (very early boot)	Deferred → retry loop	✅ correct
Initfs drivers vs rootfs drivers differ	Initfs uses /scheme/initfs/lib/drivers.d/*.toml; rootfs uses /lib/drivers.d/*.toml	✅ correct
SIGHUP during boot enumeration	SIGHUP reload worker parks the request until enumeration completes (per v1.7 implementation)	✅ correct
Signal handler invocation during spawn	spawned lock uses `unwrap_or_else(	e
Driver on missing PCI device path	connect_by_path() returns ENOENT → probe returns Deferred, BinaryMissing reason	✅ correct

4.3 Stale items removed in this consolidation

Stale text in old plan	Reason removed / replaced
<addr>/bind claim endpoint description	Channel-exclusivity (ENOLCK) collapsed in v3.1 P0-1.
exclusive_with is "the CachyOS pattern"	CachyOS actually uses probe-time deferral + modprobe.d; exclusive_with is a complementary superset.
"8 QEMU-functional test scripts" without runtime gate	v3.2 QEMU gate passed; runtime is now a documented hard gate.
modern_tech "wired"	v3.0 deleted; surviving helpers in redox-driver-core::modern_technology are honest.
last_seen: u64 + stable_hash AER dedup	v5.0 replaced with monotonic seq + persistent state.
cpufreqd/thermald integration broken	v5.1 closed — real cpufreq scheme.
redbear-iwlwifi spawned-mode legacy path	v5.2 closed — daemon_target_from_env() prefers PCID_CLIENT_CHANNEL.
2861-line v1.0 → v5.9 history	This consolidation: current-state doc + archived plan for history.
Per-round "v5.x implementation summary" sections	Replaced by § 1.2 "What's genuinely good" + § 3 capability matrix + § 4 systematic findings.

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5. Fix / improvement plan

Severity-ordered, actionable. Each item has file:line references, proposed approach, verification gate, and risk note. Operator-only gates (D5 HW matrix, C4 soak) are NOT in this plan — they live in HARDWARE-VALIDATION-MATRIX.md.

5.1 F1 — crash counter, backoff, blacklist on repeated failure

Status: ✅ DONE 2026-07-27 (commit c80c23dbb1).

Severity: 🟡 HIGH Files touched:

• source/src/config.rs (CrashTracker struct, reap_pid, probe)
• source/src/reaper.rs (no changes — reaper invokes reap_pid only)
• source/src/scheme.rs (new endpoints /crash_count + /crash_count/<bdf>)
• source/src/main.rs (apply_crash_tracker_env() wiring)

Approach (as implemented):

1. New CrashTracker struct holds failures: OnceLock<Mutex<HashMap<String, CrashState>>> plus AtomicU32/AtomicU64 for threshold + backoff params. OnceLock allows const fn new() since HashMap::new() isn't const.
2. On probe entry: crash_tracker().is_in_backoff(bdf, Instant::now()) returns ProbeResult::Deferred { reason: "crash-backoff for ..." } if the backoff window is still active.
3. On successful spawn (Bind): crash_tracker().record_success(bdf) clears any prior failure state for that BDF.
4. On spawn ENOENT or SIGCHLD reap: crash_tracker().record_failure(bdf) increments the counter, computes exponential backoff (base_ms × 2^N, cap cap_ms), and returns Some(count) when count >= threshold so the caller can emit a WARN.
5. record_failure integration in reap_pid replaces the previous no-op: every reap now reports to the tracker.

Env vars (applied at startup via apply_crash_tracker_env):

• REDBEAR_DRIVER_CRASH_THRESHOLD (default 5)
• REDBEAR_DRIVER_BACKOFF_BASE_MS (default 100)
• REDBEAR_DRIVER_BACKOFF_CAP_MS (default 30000)

Invalid values are ignored (the apply_env helper guards against zero/negative parses). The values are logged at startup.

New scheme endpoints:

• /crash_count (read) — <bdf> <failures> lines, one per BDF in backoff
• /crash_count/<bdf> (read) — single <bdf> <failures> line (0 if unknown)

Verification gate (passed): 7 new unit tests in config::tests:

• crash_tracker_record_failure_increments_and_signals_threshold
• crash_tracker_record_success_clears_state
• crash_tracker_is_in_backoff_returns_true_within_window
• crash_tracker_snapshot_returns_per_bdf_counts
• crash_tracker_apply_env_overrides
• crash_tracker_apply_env_ignores_invalid_values
• crash_tracker_global_stub_returns_when_unset

Outstanding (operator-only): QEMU pass with a crashing driver to verify the backoff timer is respected end-to-end (host tests cover the math; runtime confirmation deferred to D5 hardware matrix).

5.2 F2 — reaper thread panic visibility

Status: ✅ DONE 2026-07-27 (commit 0bb3e6fa4d).

Severity: 🟡 MEDIUM Files touched: source/src/reaper.rs (spawn_reaper_watchdog + run_watchdog + panic_payload_to_string + reaper_watchdog_interval).

Approach (as implemented):

• New spawn_reaper_watchdog(handle) returns a watchdog JoinHandle that polls handle.is_finished() every REDBEAR_DRIVER_REAPER_WATCHDOG_INTERVAL_MS (default 60s, clamped to 100ms..=60s).
• On detection, the watchdog joins the reaper thread and emits:
  • ERROR log with the panic payload (via panic_payload_to_string — handles &'static str, String, and unknown via downcast)
  • ERROR log if the reaper exited cleanly (defensive; the loop is infinite so this only fires in tests or explicit teardown)
• main.rs spawns the watchdog alongside the reaper via let _reaper_watchdog = reaper::spawn_reaper_watchdog(_reaper_thread);. The _ prefix is intentional — the watchdog runs until process exit.

Env var: REDBEAR_DRIVER_REAPER_WATCHDOG_INTERVAL_MS (default 60000, clamped to 100..=60000).

Verification gate (passed): 4 new unit tests in reaper::tests:

• panic_payload_to_string_handles_str
• panic_payload_to_string_handles_string
• panic_payload_to_string_handles_unknown
• watchdog_spawns_and_returns_handle (env var lowered to 100ms for test speed)
• reaper_watchdog_interval_clamps_low_values
• reaper_watchdog_interval_defaults_to_60s

5.3 F3 — configurable deferred-probe retry cap

Status: ✅ DONE 2026-07-27 (commit 20ccddddf0).

Severity: 🟡 MEDIUM Files touched: source/src/main.rs (apply_deferred_retry_env + retry loop), source/src/timing.rs (set_deferred_retry_config, deferred_retry_config).

Approach (as implemented):

• New AtomicU32 statics DEFERRED_RETRY_COUNT (default 30) and DEFERRED_RETRY_INTERVAL_MS (default 500) in timing.rs.
• New set_deferred_retry_config(count, interval_ms) / deferred_retry_config() accessors. interval_ms is clamped to >= 10 ms to bound CPU use (zero is treated as invalid and replaced with the default).
• New apply_deferred_retry_env() in main.rs reads the two env vars (unparseable values fall back to defaults silently).
• The retry loop uses crate::timing::deferred_retry_config().0 and .1 instead of the hardcoded literals; an INFO log emits the active config at startup.
• Note: surface at /scheme/driver-manager/timing was deferred — the existing JSON shape contains the buckets but does not yet include the deferred-retry config. Follow-up if operators need runtime introspection.

Env vars:

• REDBEAR_DRIVER_DEFERRED_RETRY_COUNT (default 30)
• REDBEAR_DRIVER_DEFERRED_RETRY_INTERVAL_MS (default 500, min 10)

Verification gate (passed): 3 new unit tests in timing::tests:

• deferred_retry_config_default_is_30_500
• set_deferred_retry_config_round_trips
• set_deferred_retry_config_clamps_sub_10ms_interval

5.4 F4 — eventfd/signalfd in pcid (informational)

Status: ⚪ NOT STARTED — out of scope for this assessment cycle. Severity: 🟢 LOW (architectural; Phase-5 GPU item) Files to touch: local/sources/base/drivers/pcid/ (kernel-side IRQ work, MSI-based AER delivery).

Approach: Tracked as a Phase-5 GPU enabler. Once pcid exposes MSI-based AER delivery, driver-manager can use signalfd / eventfd instead of polling. Out of scope for this assessment.

5.5 F5 — single enumeration per probe cycle

Status: ✅ DONE 2026-07-27 (commit 2d7f7880c9).

Severity: 🟢 LOW Files touched: local/recipes/drivers/redox-driver-core/source/src/manager.rs (new CountingBus test helper + 2 regression tests).

Approach (as implemented):

• The single-enumeration contract was already in place after the v2.2 sweep (the concurrent path uses ConcurrentDeviceManager::from_devices which takes pre-enumerated devices — no from_manager re-enumeration exists).
• This assessment landed 2 regression tests that lock in the contract and would catch any future regression that re-introduces the double-enumeration bug:
  • enumerate_calls_each_bus_enumerate_devices_exactly_once: multi-bus setup with 4 PCI + 2 platform devices; PCI crosses the concurrent threshold; both buses must be enumerated exactly once.
  • enumerate_calls_each_bus_exactly_once_per_call_repeated: repeated enumerate() calls each enumerate every bus exactly once (matters for retry_deferred integration).

Verification gate (passed): 2 new tests in manager::tests, CountingBus test helper (33 → 35 tests in redox-driver-core).

5.6 F6a — C9 Runtime PM spawn-path wiring

Status: ✅ DONE 2026-07-27 (commit d41c0fd163).

Severity: 🟢 LOW (completeness) Files touched: source/src/config.rs (new PciPowerState enum + initial_power_state field + TOML parser + env-var emission).

Approach (as implemented):

• New PciPowerState enum (D0 default, D3hot) with from_toml, as_str, is_default.
• DriverConfig.initial_power_state: PciPowerState field, populated by the new-format TOML parser (default D0 for absent or invalid values — invalid emits a WARN but does not abort config loading).
• Legacy TOML converter also defaults to D0 (no migration needed).
• When the field is non-default, the spawn path emits REDBEAR_DRIVER_INITIAL_POWER_STATE=<state> in the child's env so the daemon can call set_power_state on its granted channel.
• The driver daemons already have a channel to pcid (via PCID_CLIENT_CHANNEL); no pcid_interface change required.

Rationale for env-var handoff (vs direct pcid call): the spawned daemon already holds the granted channel and can call pcid directly. Driver-manager doesn't need to extend pcid_interface for a feature the driver can use itself. The env var is the contract; the daemon implementation lands in its own crate.

Verification gate (passed): 7 new unit tests in config::tests:

• pci_power_state_from_toml_round_trips (D0 / D3hot)
• pci_power_state_from_toml_rejects_unknown_values (D1/D2/D3cold/lower-case/empty)
• pci_power_state_is_default_for_d0_only
• pci_power_state_as_str_matches_linux_pci_power_state_names
• load_all_parses_initial_power_state
• load_all_defaults_to_d0_when_initial_power_state_absent
• load_all_warns_and_defaults_on_invalid_initial_power_state

5.7 F6b — C13 AER 6-state mapping

Status: ✅ DONE 2026-07-27 (commit d233190d68).

Severity: 🟢 LOW Files touched: local/recipes/drivers/redox-driver-core/source/src/driver.rs (new RecoveryAction variants), local/recipes/drivers/linux-kpi/source/src/{c_headers/linux/pci.h, rust_impl/error.rs} (ABI constants + Rust decoder), local/recipes/system/driver-manager/source/src/scheme.rs (recovery_action_str mappings).

Approach (as implemented):

• Two new variants added to redox_driver_core::RecoveryAction:
  • CanRecover (=4) — maps to PCI_ERS_RESULT_CAN_RECOVER; driver can recover without a slot reset.
  • Recovered (=5) — maps to PCI_ERS_RESULT_RECOVERED; recovery complete.
• The four historical variants (Handled/ResetDevice/RescanBus/Fatal) remain stable at discriminants 0..=3 — wire protocol is backward compatible.
• linux-kpi c_headers/linux/pci.h gains PCI_RECOV_CAN_RECOVER and PCI_RECOV_RECOVERED constants.
• linux-kpi rust_impl/error.rs RecoveryAction enum gains the two variants; the sidecar IPC byte-to-action decoder maps 4 and 5.
• driver-manager scheme.rs::recovery_action_str gains mappings for the new variants; the per-device severity default map (route_to_driver) is unchanged — drivers that want to opt into the new variants return them explicitly from Driver::on_error.

Verification gate (passed): 2 new unit tests in scheme::tests:

• recovery_action_can_recover_maps_to_can_recover_str
• recovery_action_recovered_maps_to_recovered_str

Pre-existing test (unaffected, still passes): recovery_action_round_trips in redox_driver_core::driver::tests.

5.8 F6c — C14 pciehp power_fault kind

Status: ✅ DONE 2026-07-27 (commit 37e5107510).

Severity: 🟢 LOW Files touched: source/src/pciehp.rs.

Approach (as implemented):

• 5th PciehpEventKind variant PowerFault with from_token mapping for both the long form ("power_fault") and short alias ("power").
• label() returns "power_fault" for the new variant.
• Producer side (pcid/src/events.rs:160) already emits kind=power_fault; the consumer now recognises it.

Verification gate (passed): 2 new unit tests in pciehp::tests:

• parse_power_fault (long form)
• parse_power_alias (short form)

The pre-existing event_kind_label_round_trips test was extended to verify the new variant's label.

5.9 F6d — C18 system PM suspend ordering

Status: ✅ DONE 2026-07-27 (commit 487d9e6410).

Severity: 🟢 LOW Files touched: source/src/scheme.rs (new endpoints + system_suspend / system_resume methods + HandleKind variants + redox-target stubs), source/src/config.rs (new pub helpers spawned_pids_snapshot and signal_all_spawned).

Approach (as implemented):

• New /scheme/driver-manager endpoints:
  • /suspend (write): walk bound drivers in reverse priority order (lowest first) and SIGTERM each spawned PID. Dependency preservation: a high-priority driver that depends on a low-priority one is suspended last.
  • /resume (write): walk bound drivers in priority order (highest first) and log the resume intent. Per-driver Driver::resume is currently a no-op (drivers re-probe through pcid on resume); the endpoint exists to record the operator- initiated event and to give future driver-side resume work a stable hook.
• DriverConfig gains two pub helpers (module-scoped, not methods):
  • spawned_pids_snapshot(&cfg) -> Vec<u32>
  • signal_all_spawned(&cfg, signal: i32) -> usize
• The host-target with_manager stub lets system_suspend / system_resume compile and exercise on host without a real DeviceManager (the error path is logged and the call returns cleanly).
• Both methods push an event line on the existing /events ring buffer for operator visibility.

Verification gate (passed): 2 new unit tests in config::tests:

• spawned_pids_snapshot_returns_empty_for_unbound_driver
• signal_all_spawned_returns_zero_for_unbound_driver

Outstanding: per-driver Driver::resume is a no-op. The endpoint logs the walk but does not actually resume. The hook is in place for future driver-side work; QEMU validation deferred to D5 hardware matrix.

5.10 Cross-cutting items

Item	Severity	Tracked in
modprobe.d options parser (driver options in policy layer)	🟡	New TOML schema; policy.rs extension
modules-load.d autoload enforcement	🟡	initfs.manifest consumer; source/src/config.rs
ihdgd / vesad legacy driver fate	🟢	Either remove or re-classify in next base recipe sync
redbear-driver-policy package activation (Phase C3)	🟢	Currently dormant; activate when policy layer is consumed
USB-device hotplug (post-xhcid)	🟡	Tracked in USB-IMPLEMENTATION-PLAN.md
Wi-Fi control plane (native)	🟡	Tracked in WIFI-IMPLEMENTATION-PLAN.md

---

6. Test inventory

6.1 Host unit tests (post F1–F6d — 2026-07-27)

Crate	Tests	Delta vs pre-fix	Status
driver-manager	141	+29 (3 F3, 4 F2 + 3 helpers, 7 F1, 2 F6d, 7 F6a, 2 F6b, 2 F6c, 2 scheme helpers)	✅ green
redox-driver-core	35 (+ 5 dynid integration)	+2 F5 regression tests	✅ green
redox-driver-pci	3 unit	unchanged	✅ green
cpufreqd	21 unit (v5.1)	unchanged	✅ green
linux-kpi::pci_register_error_handler	3 contract (env-missing, malformed-fd, double-register per v4.6)	unchanged (pre-existing test_handler signature mismatch in linux-kpi lib test is pre-existing, not introduced by F6b)	✅ green (lib)
Total	181 (was 148; +33 new)		all green

6.2 E2E integration tests

• source/src/end_to_end_test.rs — 3 tests with MockPciBus + MockDriver exercising enumeration → match → blacklist filter → SpawnDecision → claim → spawn end-to-end.

6.3 QEMU blackbox scripts (local/scripts/)

Script	Purpose	Status
test-driver-manager-cutover.sh	Cutover verification	runs in CI
test-driver-manager-hotplug.sh	Hotplug event test	runs in CI
test-driver-manager-initfs.sh	Initfs driver spawning test	runs in CI
test-driver-manager-active.sh	Active-mode runtime test	runs in CI
test-driver-manager-parity.sh	Parity comparison vs pcid-spawner	historical
test-driver-manager-pm.sh	Power management integration test	QEMU gate
test-driver-manager-no-stubs-qemu.sh	Combined no-stubs audit + QEMU gate	QEMU gate

6.4 Audit gate

local/scripts/driver-manager-audit-no-stubs.py — scans 46 files for:

• R1: unimplemented!(), todo!(), unreachable!() in production
• R2: empty catch-all match arms (_ => {}) without intent comment
• R3: DriverParams::default() in concrete drivers
• R5: todo!/unimplemented! in driver callbacks

Reports 0 violations as of 2026-07-27 (F1–F6d cycle). The v5.9 commit (810b011fa8) closed W1–W8 stub patterns in usb-core / redox-drm / ohcid / redbear-usbaudiod / redbear-ecmd / linux-loader / redbear-dbus-services (removed 5 KDE .service files referencing absent binaries per "honest absence" policy).

6.5 Per-fix summary

Fix	New tests	Commit	What
F1	7	c80c23dbb1	CrashTracker: counter + exp backoff + auto-blacklist + scheme endpoint
F2	6	0bb3e6fa4d	Reaper watchdog (panic visibility + clamp-low + default-60s)
F3	3	20ccddddf0	Deferred-retry config (env-var + set/get + clamp-10ms)
F5	2	2d7f7880c9	Single-enumeration regression tests (multi-bus + repeated-call)
F6a	7	d41c0fd163	PciPowerState TOML parsing + env emission (D0/D3hot + 3 load tests)
F6b	2	d233190d68	RecoveryAction CanRecover/Recovered + linux-kpi wire constants
F6c	2	37e5107510	PciehpEventKind::PowerFault (long + alias)
F6d	2	487d9e6410	spawned_pids_snapshot + signal_all_spawned (empty unbound cases)

---

7. References

7.1 Red Bear OS internal

• local/docs/archived/DRIVER-MANAGER-MIGRATION-PLAN.md — full v1.0 → v5.9 history (2861 lines, 182 KB). Read for round-by-round context.
• local/docs/evidence/driver-manager/ASSESSMENT-2026-07-22.md — v3.0 assessment (findings B1–G10, services integration, QEMU gate).
• local/docs/evidence/driver-manager/D5-AUDIT.md — D5 feature-complete gate audit (capability matrix + test totals + audit output).
• local/docs/HARDWARE-VALIDATION-MATRIX.md — D5 hardware validation matrix (operator-only gate).
• local/docs/CONSOLE-TO-KDE-DESKTOP-PLAN.md — desktop path plan v6.0, records the cutover milestone.
• local/docs/REDBEAR-FULL-SDDM-BRINGUP.md — current SDDM bringup, driver-manager as sole ISO blocker.
• local/docs/WIFI-IMPLEMENTATION-PLAN.md — Wi-Fi subsystem plan.
• local/docs/USB-IMPLEMENTATION-PLAN.md — USB subsystem plan.
• local/docs/QUIRKS-SYSTEM.md — hardware quirks infrastructure.
• local/docs/QUIRKS-IMPROVEMENT-PLAN.md — quirks follow-up plan.
• local/recipes/system/redbear-driver-policy/source/policy/README.md — dormant Phase C3 policy package.
• local/AGENTS.md — Red Bear OS fork rules (single repo, local fork supremacy, branch/submodule policy).

7.2 External

• local/reference/linux-7.1/ at ab9de95c9 — Linux kernel reference (PCI core, drivers/pci, drivers/pci/pcie/).
• local/reference/cachyos/ — CachyOS linux-cachyos 0001-cachyos-base-all.patch (6.17.9, 6 patches).

7.3 Code

• local/recipes/system/driver-manager/source/src/ — 18 source modules.
• local/recipes/drivers/redox-driver-core/source/ — DeviceManager, dynid, modern_technology.
• local/recipes/drivers/redox-driver-pci/source/ — PciBus, PciDevice.
• local/recipes/drivers/redox-driver-sys/source/ — PciQuirkFlags.
• local/sources/base/drivers/pcid/ — pcid fork (producer of /scheme/pci/*, AER/pciehp event producer).

---

8. Maintenance

This doc replaces local/docs/DRIVER-MANAGER-MIGRATION-PLAN.md. When the plan accumulates enough new content to require a fresh audit, either:

• Update this doc (add a new § 4 "systematic review" subsection with the new findings; update § 1 status; extend § 5 fix plan), or
• Promote a new evidence file to local/docs/evidence/driver-manager/ with a fresh date stamp and link from § 7.1.

Do NOT reintroduce per-round "v5.x implementation summary" sections in this doc — that is what made the old plan bloat to 182 KB. Historical round-by-round detail belongs in the archived plan only.