device-manager: data-driven driver matching via /etc/devices.csv

Replace the three hardcoded switch tables (pciDriverForIdentity, hidDriverFor,
usbDriverForIdentity) with an authoritative, human-readable device registry the
manager reads at boot. Matching is most-specific-wins across
base/subclass/prog_if/vendor/device/subsystem/hid, so a precise vendor:device
rule and a generic class rule coexist; an unmatched device is logged, never
guessed. This resolves docs' "matching stays code until the third bus".

- ABI: child_added and DeviceDescriptor gain vendor/device/subsystem; child_added
  gains a bus discriminator (BusKind) so PCI and USB class triples match against
  the right namespace.
- pci-bus reads vendor/device (config 0x00) and subsystem (0x2C, type-0) and
  reports them.
- library/device/registry: freestanding CSV parser + matchDriver() with
  specificity scoring; 5 unit tests wired into `zig build test`.
- etc/devices.csv bundled into the initrd; the kernel serves /etc directly, so
  the manager reads it before any filesystem service is up (fat starts later).
- virtio-gpu: drop the now-redundant post-spawn 1AF4:1050 re-confirm, since the
  registry binds this driver by exact identity.
- Remove the orphaned system/drivers/display driver (unreferenced by build or
  registry).
- docs: new devices-csv.md; device-manager.md "matching stays code" resolved.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KJqSiLLchDUUCoXn5jsiwd

build.zig

@@ -284,6 +284,13 @@ pub fn build(b: *std.Build) void {
     const pci_class_module = b.addModule("pci-class", .{
         .root_source_file = b.path("library/device/pci/pci-class.zig"),
     });
+    // The device registry: parse /etc/devices.csv into match rules and bind a
+    // reported device to a driver — the data-driven, authoritative replacement for
+    // the manager's hand-written switch tables. Pure logic (no hardware, no
+    // syscalls), so it unit-tests with plain `zig test`; the manager imports it.
+    const device_registry_module = b.addModule("device-registry", .{
+        .root_source_file = b.path("library/device/registry/device-registry.zig"),
+    });
     // ACPI/PnP hardware-ID (_HID) names — the flat analog of pci-class for acpi_device
     // nodes. Also shared reference data.
     // The AML interpreter, a build module so the ring-3 acpi service can run the
@@ -729,12 +736,10 @@ pub fn build(b: *std.Build) void {
     if (discovery == .acpi) programModule(discovery_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     if (discovery == .acpi) programModule(discovery_exe).addImport("power-protocol", power_protocol_module);
     const device_manager_exe = addUserBinary(b, kernel_target, &default_imports, "device-manager", "system/services/device-manager/device-manager.zig");
-    // Names the xHCI PCI class triple from the shared taxonomy instead of a bare 0x0C0330.
-    programModule(device_manager_exe).addImport("pci-class", pci_class_module);
     programModule(device_manager_exe).addImport("device-manager-protocol", device_manager_protocol_module);
-    // The manager matches reported USB interfaces by their (class,subclass,protocol)
-    // triple (usbDriverForIdentity), built from the named usb-ids codes.
-    programModule(device_manager_exe).addImport("usb-ids", usb_ids_module);
+    // Driver matching is data-driven: the manager parses /etc/devices.csv into this
+    // module's rules and binds each reported device by most-specific match.
+    programModule(device_manager_exe).addImport("device-registry", device_registry_module);
     // The input service and its exercisers: the fan-out server, a hardware-free synthetic
     // source, and a subscriber that doubles as the `input` test's oracle. See docs/input.md.
     const input_exe = addUserBinary(b, kernel_target, &default_imports, "input", "system/services/input/input.zig");
@@ -764,6 +769,11 @@ pub fn build(b: *std.Build) void {
         .{ .path = "system/services/input", .binary = input_exe.getEmittedBin() },
         .{ .path = "system/services/discovery", .binary = discovery_exe.getEmittedBin() },
         .{ .path = "system/services/logger", .binary = logger_exe.getEmittedBin() },
+        // A data file, not a binary: the device registry the manager reads at boot.
+        // Packing it under /etc makes the kernel auto-mount /etc as a read-only
+        // initrd tree (system/kernel/vfs.zig setInitialRamdisk), so the manager can
+        // fs.open("/etc/devices.csv") with no filesystem service running.
+        .{ .path = "etc/devices.csv", .binary = b.path("etc/devices.csv") },
         .{ .path = "system/drivers/ps2-bus", .binary = ps2_bus_exe.getEmittedBin() },
         .{ .path = "system/drivers/ps2-keyboard", .binary = ps2_keyboard_exe.getEmittedBin() },
         .{ .path = "system/drivers/ps2-mouse", .binary = ps2_mouse_exe.getEmittedBin() },
@@ -1078,6 +1088,7 @@ pub fn build(b: *std.Build) void {
         "library/device/acpi/aml/aml.zig", // AML parse + interpret, incl. Notify dispatch (M21)
         "library/device/usb/usb-abi.zig", // wire sizes + bit packings + set-up packet encodings
         "library/device/usb/usb-ids.zig", // class/subclass/protocol code assignments
+        "library/device/registry/device-registry.zig", // /etc/devices.csv parse + most-specific driver match
         "library/device/mmio/mmio.zig", // barriers assemble + registers round-trip
         "system/drivers/ps2-bus/scancode.zig", // set-2 decode + keyboard state machine
         "system/drivers/ps2-bus/mouse-packet.zig", // 3-byte mouse packet assembly