Two related changes to make device identities legible in the boot log and in
the code that matches on them.
Logging: the pci-bus driver decodes each function's class/subclass/prog-IF
triple to human names (via the existing pci-class module), and the acpi
service appends each _HID's human name (via acpi-ids) to its report line. So
"class 0x01 (Mass Storage Controller) subclass 0x06 (Serial ATA Controller)
progif 0x01 (AHCI 1.0)" reads straight off the log when writing a driver.
Naming: a new coding standard ("Named values, not magic numbers") says a value
with meaning gets a name, prefer an enum for value sets. Applied:
- pci-class is refactored from u8-switch tables into a BaseClass enum plus
per-class SubClass/ProgIf enums with name() methods (the usb-ids shape). The
public className/subclassName/progIfName(u8...) API is unchanged, so the
hardware-byte decoders (pci-bus, the kernel dump) are untouched; output is
byte-identical.
- the device-manager builds the xHCI class triple from named parts instead of
a bare 0x0C0330.
- the acpi service's _CRS walk names its resource-descriptor tags as
SmallResourceType/LargeResourceType enums, and the _HID integer decode uses
the AML module's existing *_opcode constants (now re-exported from aml.zig)
rather than bare 0x0A/0xFF/... literals.
The kernel no longer folds AML Device objects into the device tree — the
ring-3 acpi service is the sole builder of _HID device nodes. The kernel
keeps building the namespace only for the \_S5 sleep type, and still
seeds the static tables (MADT, HPET, MCFG, FADT) and the acpi-tables node.
The device manager matches ps2-bus from the service's _HID reports
(PNP0303 / PNP0F13, singleton-deduped) instead of boot-snapshot nodes;
its dead boot-snapshot ps2 arm is gone. The service registers every
device before reporting any, so a driver the manager spawns on the first
report already sees the full set — no keyboard-before-mouse race. The
acpi-ps2 scenario proves the whole chain: report -> spawn -> ps2-bus
finds the controller and attaches its keyboard, entirely in ring 3. The
ioport test moved to the acpi-tables I/O window, since the kernel-built
PS/2 node it used to scan for no longer exists. The retired
device-building functions in acpi.zig are dead but retained (a botched
mechanical deletion is worse mid-migration than a follow-up sweep, which
is flagged as a task). Suite 58/58.
AML method evaluation now runs in userspace touching real hardware: the
service builds an interpreter with a ring-3 Hal (port I/O routed through
its claimed acpi-tables node; a scratch page backs SystemMemory maps so a
stray OperationRegion degrades to zeros instead of faulting a process
that cannot map arbitrary physical memory). It walks the namespace and,
for each present _HID device that is not a PCI root, evaluates _CRS,
registers it under acpi-tables, and reports it with its EISA-decoded hid.
Containment for this needed the broker's irq check to become range-based
— an interrupt line is still indivisible, but a parent may own a range,
so the acpi-tables node's broad irq window contains its children's legacy
lines (a length-1 range is exactly the old equality, so single-irq
parents are unaffected). ChildAdded gained a hid field for firmware
string identity. Matching those reports to drivers stays off until M20.3,
so ps2-bus still comes up via the kernel path — no regression. The
acpi-report scenario proves the PS/2 keyboard (io 0x60/0x64 + IRQ) and
mouse (IRQ) are reported with their resources. Suite 57/57.
The AML module becomes a build module compiled into both the kernel (for
the \_S5 sleep state it still needs) and the new acpi service — one
source, two builds, no fork. The kernel publishes a single acpi-tables
node: the DSDT/SSDT blobs as memory resources, a broad io_port grant (the
honest trust boundary — firmware AML names whatever ports it chose, known
only after parsing), and the SCI for the M21 event track. The acpi
service claims the node, maps each blob through the ordinary mmio grant
(which preserves the sub-page offset onto the bytecode), and runs the
same parser the kernel does. It self-verifies its namespace Device count
against the kernel's — 34 = 34 — deterministically via an argv the
acpi-parse test passes, so no racing the shared serial buffer. Parse-only
touches no hardware; OperationRegion evaluation waits for _CRS/_STA in
M20.2. The manager spawns 'discovery' (the neutral ramdisk name) at
startup. Suite 56/56.
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.
The host bridge now carries MMIO apertures derived from the boot memory
map's gaps below 4 GiB (largest three, sort-merged; a single after-the-
last-region hole dies on OVMF's flash at the top) plus one aperture above
the described space — so a user-space device_register of PCI functions
with BAR resources can pass containment. The discovery test asserts
every PCI memory resource lies inside a bridge window and names any
escapee. device_register is idempotent on exact (parent, class, identity,
resources) match — a restarted registering bus cannot duplicate its
children; proven directly against the broker in the bus test.
ChildAdded gains device_id so a report can carry the registered kernel
id a matched driver needs as its assignment.
Applications ask the device manager for the tree (enumerate: a header
plus ChildEntry records) and subscribe to published add/remove events by
handing their endpoint over as the call's capability — the input-service
pattern; events are the same ChildAdded/ChildRemoved structs the bus
drivers send, one encoding in both directions. device-list is the first
client: it prints the tree, subscribes, and narrates the events through
a driver restart. The protocol's message maximum is capped at the
kernel's IPC MESSAGE_MAXIMUM (256 bytes, ten entries per reply; paging
joins the protocol when a tree outgrows one message). The startUserTask
debug print is gone: it wrote to serial unserialized against user-space
lines and sheared concurrent log markers in half — the root cause of the
scenario flakes.
child_added/child_removed join the device-manager protocol. The driver
maps its register BAR (resource 0 is the ECAM config space; the walk
starts at 1), reads CAPLENGTH and HCSPARAMS1, and reads one PORTSC per
port: the connect bit and speed class come straight from hardware, no
rings needed to see the devices. The manager mirrors reported children
keyed by (parent, port), remembers which instance reported each, and
prunes a dead reporter's children before deciding the restart — the
children describe protocol state that died with the process. The
usb-report scenario drives the whole loop: two QEMU devices reported,
reporter killed, children pruned, driver respawned with backoff, and the
new instance re-claims, re-scans, and re-reports.
The manager is now a harness service on the well-known .device_manager
endpoint. Every driver spawns supervised; drivers with an assignment must
hello (device-manager-protocol, versioned) within a deadline enforced by
a timer sweep. Exit reasons drive the restart decision: clean exits stay
down, faults restart with 300/600/1200ms backoff, and three fast deaths
mark a driver failed instead of respawning forever. usb-xhci-bus is the
first conforming driver; the crash-test fixture claims a device, hellos,
and faults on purpose — each respawn re-proving claim release on death
through the manager's own path. maximum_tasks grows 16 -> 32: the
initial-ramdisk sweep (15 binaries at once) was intermittently
overflowing the static pool.
Turn acpi-ids.zig's flat name table into a HardwareId enum modeled on
ps2-library's Port: one entry() switch holds the registry (variant ->
_HID string + human-readable name), with hid(), description(), and
fromHid() methods. The free description(hid) lookup the kernel's
device-tree dump uses survives, implemented over the enum, and a new
test round-trips every variant through fromHid.
Callers now name the device instead of quoting its id:
- ps2-library's DeviceType.hid() and ps2-bus's descriptor lookups use
HardwareId.ps2_keyboard / .ps2_mouse.
- device-manager's driverFor parses the HID once with fromHid and
switches on named values.
- acpi.zig's isPciRootNode carried the same ids twice, as strings and
as packed-EISA integers (0x030AD041/0x080AD041); both branches now
decode to the string form and answer through one isPciRootHid helper
using .pci_bus / .pci_express_root_bridge.
- build.zig threads the acpi-ids module (previously kernel-only) into
every user binary, like xkeyboard-config.
process_enumerate snapshots the task table (the device_enumerate shape, so
ps is a user program); system_spawn returns the child id, records the caller
as supervisor, and takes an exit endpoint; process_kill is allowed only for
the supervisor. Every death — exit, fault, or kill — posts a child-exit badge
to that endpoint (the IRQ-as-IPC pattern as SIGCHLD). A target caught off-CPU
is reaped in place; a running one is condemned and finished at its next
system call or tick, guarded so teardown never lands mid-kernel-operation.
Tested by process-list, process-kill, and supervision (a ring-3 supervisor
exercising the whole surface); design notes in docs/process-management.md.
Add a `system_spawn(name)` system call: the kernel loads a binary bundled in the
initial-ramdisk, by name, as a fresh ring-3 process. It's the mechanism a user-space
supervisor needs — discovery and policy stay in user space, the kernel only spawns.
The kernel already holds the initial-ramdisk image from the boot handoff; it now
stashes it (process.setInitialRamdisk) so the handler can resolve names, bounds-checks
the name into the user half like debug_write, and returns -1 for an unknown name or a
load failure. Ungated for now (any process may spawn any bundled binary); a spawn
capability belongs here once the model grows one.
The device manager stops logging "would spawn it" and calls runtime.system.spawn on
its matched driver. On QEMU it discovers the HPET, matches `hpet`, and spawns it — and
the driver comes all the way up (claims the timer, maps its MMIO, binds and services
its IRQ, prints "hpet: ok"). The device-manager test now keys on that final marker:
since only the manager is spawned, `hpet: ok` appearing proves the whole
discover -> match -> system_spawn -> driver-up chain end to end.
Transitional: the kernel still auto-spawns the whole initial-ramdisk at boot, so a
real boot briefly double-spawns hpet (the second claim fails harmlessly). Increment 3
removes that redundancy so the manager is the sole owner of driver spawning. Suite
36/36 plus host tests.
The device manager is the ring-3 process that turns the device tree into a running
system — the udev-analog. It is mechanism-vs-policy done right: the kernel
enumerates the hardware and enforces the claim capability; this decides which
driver serves which device, using no special privilege (the same device_enumerate
any process could call).
This first increment does the discovery + matching half: system/services/
device-manager enumerates /system/devices, matches each device to a driver by
class (a small static policy table), and logs the decision — finding the HPET
(a timer) and deciding `hpet` serves it. It does not spawn yet: spawning needs a
`system_spawn` system call (the kernel spawns every initial-ramdisk binary in a
loop today), which is the next increment. New `device-manager` test; suite 36/36
plus host tests.
Daniel Samson