diff --git a/build.zig b/build.zig
index 1f404f5..88406b9 100644
--- a/build.zig
+++ b/build.zig
@@ -583,6 +583,7 @@ pub fn build(b: *std.Build) void {
         "system/devices/device-abi.zig",
         "system/devices/pci-class.zig", // class/subclass/prog-IF name decoding
         "system/devices/acpi-ids.zig", // _HID name decoding
+        "system/devices/aml/aml.zig", // AML parse + interpret, incl. Notify dispatch (M21)
         "system/devices/usb-abi.zig", // wire sizes + bit packings + set-up packet encodings
         "system/devices/usb-ids.zig", // class/subclass/protocol code assignments
         "library/mmio/mmio.zig", // barriers assemble + registers round-trip
diff --git a/docs/m21-plan.md b/docs/m21-plan.md
index 7ad0928..af6b946 100644
--- a/docs/m21-plan.md
+++ b/docs/m21-plan.md
@@ -84,12 +84,14 @@ auto-merge to main when the branch is green; keep the branch; push everything.
       logs `power: button pressed`, publishes `power_button`, acks. Scenario
       `power-button` injects a real `system_powerdown` via QMP; initial-ramdisk
       timeout 30→60s for the service's added boot work; suite 59/59).
-- [ ] **M21.2** — Notify + GPE dispatch: interpreter handles `notify_opcode`
-      into a bounded queue drained after evaluate(); on GPE status bits the
-      service evaluates `\_GPE._Lxx`/`_Exx`, maps notified nodes to events
-      (PNP0C0A→battery, ACPI0003→ac, PNP0C0D→lid, else generic), clears
-      GPE_STS, acks. EC `_Qxx` explicitly out (hardware track). Host unit
-      tests for Notify in aml.zig; aml.zig joins the `zig build test` loop.
+- [x] **M21.2** — Notify + GPE dispatch (interpreter handles `notify_opcode`
+      into a bounded queue, cleared per-evaluate, drained via
+      `takeNotifications`; the service walks GPE status/enable bytes, evaluates
+      `\_GPE._Lxx`/`_Exx` per active bit, maps notified nodes to events
+      (battery/ac/lid/generic), clears GPE_STS write-1, acks. EC `_Qxx` out.
+      Host unit test with hand-encoded AML proves the queue; aml.zig joined the
+      `zig build test` loop. QEMU raises no GPEs — suite is regression net,
+      59/59).
 - [ ] **M21.3** — orderly shutdown: init keeps child ids (spawnSupervised +
       exit endpoint), binds signals, subscribes to `.power`; on `power_button`
       logs `init: shutting down`, runs `stop(child, 2000, endpoint)` in
diff --git a/system/devices/aml/aml.zig b/system/devices/aml/aml.zig
index 8ad4b66..8206c07 100644
--- a/system/devices/aml/aml.zig
+++ b/system/devices/aml/aml.zig
@@ -230,3 +230,31 @@ test "interpreter runs a method with args, arithmetic, and control flow" {
     const lo = try interpreter.evaluate(tst, &.{.{ .integer = 2 }}); // 2+5=7 !> 10 -> 0
     try std.testing.expectEqual(@as(u64, 0), try lo.asInteger());
 }
+
+test "interpreter records Notify(device, code)" {
+    // Device(DEV_) { Name(_HID, 0x030AD041) }   // PNP0A03-ish placeholder
+    // Method(TST_, 0) { Notify(DEV_, 0x80); Return(Zero) }
+    // Encoded: a Device holding a Name, then a Method issuing Notify on it.
+    const blob = [_]u8{
+        0x5B, 0x82, 0x0F, 0x44, 0x45, 0x56, 0x5F, // Device(DEV_) len=0x0F (pkglen + DEV_ + Name)
+        0x08, 0x5F, 0x48, 0x49, 0x44, 0x0C, 0x41, 0xD0, 0x0A, 0x03, // Name(_HID, DWord 0x030AD041)
+        0x14, 0x0F, 0x54, 0x53, 0x54, 0x5F, 0x00, // Method(TST_, 0) len=0x0F (pkglen + TST_ + flags + body)
+        0x86, 0x44, 0x45, 0x56, 0x5F, 0x0A, 0x80, // Notify(DEV_, 0x80)
+        0xA4, 0x00, // Return(Zero)
+    };
+
+    var arena = std.heap.ArenaAllocator.init(std.testing.allocator);
+    defer arena.deinit();
+    var result = try parse(arena.allocator(), &.{&blob});
+    const namespace = &result.namespace;
+    const tst = namespace.resolve(namespace.root, false, 0, &.{.{ 'T', 'S', 'T', '_' }}) orelse return error.NoMethod;
+    const dev = namespace.resolve(namespace.root, false, 0, &.{.{ 'D', 'E', 'V', '_' }}) orelse return error.NoDevice;
+
+    var interpreter = Interpreter.init(namespace, .{ .mapMmio = noMap, .pioRead = noRead, .pioWrite = noWrite }, arena.allocator());
+    _ = try interpreter.evaluate(tst, &.{});
+
+    const events = interpreter.takeNotifications();
+    try std.testing.expectEqual(@as(usize, 1), events.len);
+    try std.testing.expectEqual(dev, events[0].node);
+    try std.testing.expectEqual(@as(u64, 0x80), events[0].code);
+}
diff --git a/system/devices/aml/interpreter.zig b/system/devices/aml/interpreter.zig
index bef89d8..a75cc03 100644
--- a/system/devices/aml/interpreter.zig
+++ b/system/devices/aml/interpreter.zig
@@ -141,6 +141,9 @@ const Frame = struct {
 /// A CreateField binding: a name that indexes into a buffer object.
 const BufferField = struct { buffer: *Node, byte_off: usize, bit_width: u32 };
 
+/// One Notify(device, code) the interpreter executed.
+pub const NotifyEvent = struct { node: *Node, code: u64 };
+
 pub const Interpreter = struct {
     namespace: *Namespace,
     hal: Hal,
@@ -149,6 +152,11 @@ pub const Interpreter = struct {
     dynamic_overrides: std.AutoHashMapUnmanaged(*Node, Object) = .{},
     /// CreateField bindings active for the current evaluation.
     fields: std.AutoHashMapUnmanaged(*Node, BufferField) = .{},
+    /// Notify(device, code) operations the last evaluation executed — a GPE or
+    /// EC handler tells the OS "look at this device" this way. Bounded; the
+    /// caller drains it with `takeNotifications` after `evaluate` (M21).
+    notify_queue: [16]NotifyEvent = undefined,
+    notify_count: usize = 0,
 
     pub fn init(namespace: *Namespace, hal: Hal, arena: std.mem.Allocator) Interpreter {
         return .{ .namespace = namespace, .hal = hal, .arena = arena };
@@ -157,6 +165,7 @@ pub const Interpreter = struct {
     /// Evaluate a namespace object: invoke a Method, read a Name's value, or read a
     /// Field. Resets per-evaluation runtime state first.
     pub fn evaluate(self: *Interpreter, node: *Node, args: []const Object) Error!Object {
+        self.notify_count = 0;
         self.dynamic_overrides.clearRetainingCapacity();
         self.fields.clearRetainingCapacity();
         return self.invoke(node, args);
@@ -267,6 +276,8 @@ pub const Interpreter = struct {
             },
             opcode.to_buffer_opcode => try self.passThroughUnary(current, frame),
 
+            opcode.notify_opcode => try self.notify(current, frame),
+
             opcode.extended_opcode_prefix => try self.ext(current, frame),
 
             // CreateXField: source, index, name  (bit widths differ by op)
@@ -542,6 +553,36 @@ pub const Interpreter = struct {
         try self.storeInto(current, frame, value);
     }
 
+    /// Notify(SuperName, NotifyValue): resolve the named device, evaluate the
+    /// code, and record the pair for the caller to dispatch. AML control flow
+    /// continues (Notify returns nothing).
+    fn notify(self: *Interpreter, current: *Cursor, frame: *Frame) Error!Object {
+        const lead = current.peek() orelse return error.Truncated;
+        var target: ?*Node = null;
+        if (isNameStart(lead)) {
+            const name_path = try current.nameString();
+            target = self.namespace.resolve(frame.scope, name_path.rooted, name_path.parents, name_path.slice());
+        } else {
+            // A non-name SuperName (Local/Arg holding a reference).
+            const obj = try self.term(current, frame);
+            if (obj == .reference) target = obj.reference;
+        }
+        const code = try self.evaluateInteger(current, frame);
+        if (target) |node| {
+            if (self.notify_count < self.notify_queue.len) {
+                self.notify_queue[self.notify_count] = .{ .node = node, .code = code };
+                self.notify_count += 1;
+            }
+        }
+        return .uninitialized;
+    }
+
+    /// The Notify events the last `evaluate` produced. Valid until the next
+    /// `evaluate` clears the queue.
+    pub fn takeNotifications(self: *Interpreter) []const NotifyEvent {
+        return self.notify_queue[0..self.notify_count];
+    }
+
     fn storeInto(self: *Interpreter, current: *Cursor, frame: *Frame, value: Object) Error!void {
         const lead = current.peek() orelse return error.Truncated;
         if (isNameStart(lead)) {
diff --git a/system/drivers/ps2-bus/keyboard.zig b/system/drivers/ps2-bus/keyboard.zig
index a38f826..2b5ba0f 100644
--- a/system/drivers/ps2-bus/keyboard.zig
+++ b/system/drivers/ps2-bus/keyboard.zig
@@ -72,17 +72,17 @@ fn modifierWord(modifiers: scancode.ModifierSnapshot) u32 {
 pub fn main(init: runtime.process.Init) void {
     const hid = init.arguments.get(1).?;
     if (hid.len == 0) {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: no HID argument\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: no HID argument\n");
         return;
     }
-    writeLine("system/drivers/ps2-bus/keyboard: starting for hid {s}\n", .{hid});
+    writeLine("/system/drivers/ps2-bus/keyboard: starting for hid {s}\n", .{hid});
 
     const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: out of memory\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: out of memory\n");
         return;
     };
     if (device.findDeviceDescriptorByHid(buffer, hid) == null) {
-        writeLine("system/drivers/ps2-bus/keyboard: no device for hid {s}\n", .{hid});
+        writeLine("/system/drivers/ps2-bus/keyboard: no device for hid {s}\n", .{hid});
         return;
     }
 
@@ -90,38 +90,38 @@ pub fn main(init: runtime.process.Init) void {
     // absent (as today) it defaults to us.
     const layout_name = init.arguments.get(2) orelse "us";
     const layout = xkb.byName(layout_name) orelse xkb.us;
-    writeLine("system/drivers/ps2-bus/keyboard: layout {s}\n", .{layout.name});
+    writeLine("/system/drivers/ps2-bus/keyboard: layout {s}\n", .{layout.name});
 
     // Attach to the bus: hand it our endpoint, and it forwards every byte the
     // keyboard sends (it owns the controller; we own the decoding).
     const bus = lookupBus() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: ps2-bus service unavailable\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: ps2-bus service unavailable\n");
         return;
     };
     const endpoint = ipc.createIpcEndpoint() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: no endpoint\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: no endpoint\n");
         return;
     };
     var attach = ps2.AttachRequest{ .device_type = @intFromEnum(ps2.DeviceType.keyboard) };
     var attach_reply: [@sizeOf(ps2.AttachReply)]u8 = undefined;
     const attached = ipc.callCap(bus, std.mem.asBytes(&attach), &attach_reply, endpoint) catch {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: attach call failed\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: attach call failed\n");
         return;
     };
     if (attached.len < @sizeOf(ps2.AttachReply) or
         std.mem.bytesToValue(ps2.AttachReply, attach_reply[0..@sizeOf(ps2.AttachReply)]).status != @intFromEnum(ps2.AttachStatus.ok))
     {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: attach refused\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: attach refused\n");
         return;
     }
 
     // Broadcast keyboard events through the input service so programs can listen
     // for them (docs/input.md).
     var source = runtime.input.connectSource() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus/keyboard: input service unavailable\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: input service unavailable\n");
         return;
     };
-    _ = runtime.system.write("system/drivers/ps2-bus/keyboard: ok\n");
+    _ = runtime.system.write("/system/drivers/ps2-bus/keyboard: ok\n");
 
     var decoder = scancode.Decoder{};
     var state = scancode.KeyboardState{};
diff --git a/system/drivers/ps2-bus/mouse.zig b/system/drivers/ps2-bus/mouse.zig
index c70d0a0..c106eab 100644
--- a/system/drivers/ps2-bus/mouse.zig
+++ b/system/drivers/ps2-bus/mouse.zig
@@ -51,50 +51,50 @@ pub fn main(init: runtime.process.Init) void {
     const hid = init.arguments.get(1).?;
 
     if (hid.len == 0) {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: no HID argument\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: no HID argument\n");
         return;
     }
-    writeLine("system/drivers/ps2-bus/mouse: starting for hid {s}\n", .{hid});
+    writeLine("/system/drivers/ps2-bus/mouse: starting for hid {s}\n", .{hid});
 
     const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: out of memory\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: out of memory\n");
         return;
     };
     if (device.findDeviceDescriptorByHid(buffer, hid) == null) {
-        writeLine("system/drivers/ps2-bus/mouse: no device for hid {s}\n", .{hid});
+        writeLine("/system/drivers/ps2-bus/mouse: no device for hid {s}\n", .{hid});
         return;
     }
 
     // Attach to the bus: hand it our endpoint, and it forwards every byte the
     // mouse sends (it owns the controller; we own the decoding).
     const bus = lookupBus() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: ps2-bus service unavailable\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: ps2-bus service unavailable\n");
         return;
     };
     const endpoint = ipc.createIpcEndpoint() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: no endpoint\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: no endpoint\n");
         return;
     };
     var attach = ps2.AttachRequest{ .device_type = @intFromEnum(ps2.DeviceType.mouse) };
     var attach_reply: [@sizeOf(ps2.AttachReply)]u8 = undefined;
     const attached = ipc.callCap(bus, std.mem.asBytes(&attach), &attach_reply, endpoint) catch {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: attach call failed\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: attach call failed\n");
         return;
     };
     if (attached.len < @sizeOf(ps2.AttachReply) or
         std.mem.bytesToValue(ps2.AttachReply, attach_reply[0..@sizeOf(ps2.AttachReply)]).status != @intFromEnum(ps2.AttachStatus.ok))
     {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: attach refused\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: attach refused\n");
         return;
     }
 
     // Broadcast mouse events through the input service so programs can listen
     // for them (docs/input.md).
     var source = runtime.input.connectSource() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus/mouse: input service unavailable\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus/mouse: input service unavailable\n");
         return;
     };
-    _ = runtime.system.write("system/drivers/ps2-bus/mouse: ok\n");
+    _ = runtime.system.write("/system/drivers/ps2-bus/mouse: ok\n");
 
     var assembler = mouse_packet.Assembler{};
     var buttons: u32 = 0;
diff --git a/system/drivers/ps2-bus/ps2-bus.zig b/system/drivers/ps2-bus/ps2-bus.zig
index 2438a92..8f258ad 100644
--- a/system/drivers/ps2-bus/ps2-bus.zig
+++ b/system/drivers/ps2-bus/ps2-bus.zig
@@ -30,19 +30,19 @@ fn writeLine(comptime fmt: []const u8, arguments: anytype) void {
 /// attaches, or null if nothing was spawned.
 fn spawnIdentifiedDriver(controller: ps2.Controller, port: ps2.Port) ?ps2.DeviceType {
     const device_type = controller.identifyDevice(port) orelse {
-        writeLine("system/drivers/ps2-bus: identify timed out on port {s}\n", .{@tagName(port)});
+        writeLine("/system/drivers/ps2-bus: identify timed out on port {s}\n", .{@tagName(port)});
         return null;
     };
     const driver_name = device_type.driverName() orelse {
-        writeLine("system/drivers/ps2-bus: unrecognized device on port {s}\n", .{@tagName(port)});
+        writeLine("/system/drivers/ps2-bus: unrecognized device on port {s}\n", .{@tagName(port)});
         return null;
     };
     const hid = device_type.hid() orelse "";
     if (runtime.system.spawnWithArguments(driver_name, &.{hid}) != null) {
-        writeLine("system/drivers/ps2-bus: port {s} is a {s}, spawned {s}\n", .{ @tagName(port), hid, driver_name });
+        writeLine("/system/drivers/ps2-bus: port {s} is a {s}, spawned {s}\n", .{ @tagName(port), hid, driver_name });
         return device_type;
     }
-    writeLine("system/drivers/ps2-bus: failed to spawn {s}\n", .{driver_name});
+    writeLine("/system/drivers/ps2-bus: failed to spawn {s}\n", .{driver_name});
     return null;
 }
 
@@ -83,7 +83,7 @@ fn handleAttach(message: []const u8, got: ipc.Received, out: []u8) usize {
         const device_type = maybe_type orelse continue;
         if (@intFromEnum(device_type) != request.device_type) continue;
         port_endpoints[port_index] = endpoint;
-        writeLine("system/drivers/ps2-bus: {s} driver attached\n", .{@tagName(device_type)});
+        writeLine("/system/drivers/ps2-bus: {s} driver attached\n", .{@tagName(device_type)});
         return reply.write(out, .ok);
     }
     return reply.write(out, .no_such_device);
@@ -91,7 +91,7 @@ fn handleAttach(message: []const u8, got: ipc.Received, out: []u8) usize {
 
 pub fn main() void {
     const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
-        _ = runtime.system.write("system/drivers/ps2-bus: out of memory\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: out of memory\n");
         return;
     };
 
@@ -103,16 +103,16 @@ pub fn main() void {
     // is on which port is decided later by identify, not by this HID.
     const maybe_controller_device_descriptor = device.findDeviceDescriptorByHid(buffer, acpi_ids.HardwareId.ps2_keyboard.hid());
     if (maybe_controller_device_descriptor) |controller_device_descriptor| {
-        _ = runtime.system.write("system/drivers/ps2-bus: found PS/2 controller\n");
-        _ = runtime.system.write("system/drivers/ps2-bus: initializing controller\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: found PS/2 controller\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: initializing controller\n");
 
         if (!device.claim(controller_device_descriptor.id)) {
-            _ = runtime.system.write("system/drivers/ps2-bus: unable to claim controller \n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: unable to claim controller \n");
             return;
         }
 
         const controller = ps2.Controller.init(controller_device_descriptor) orelse {
-            _ = runtime.system.write("system/drivers/ps2-bus: controller is missing its IO ports\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: controller is missing its IO ports\n");
             return;
         };
         maybe_controller = controller;
@@ -123,7 +123,7 @@ pub fn main() void {
         controller.flushOutputBuffer();
 
         const current = controller.readConfigurationByte() orelse {
-            _ = runtime.system.write("system/drivers/ps2-bus: controller configuration timed out\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: controller configuration timed out\n");
             return;
         };
 
@@ -132,49 +132,49 @@ pub fn main() void {
             ps2.configuration_first_port_translation);
 
         if (controller.writeConfigurationByte(update) == null) {
-            _ = runtime.system.write("system/drivers/ps2-bus: controller configuration timed out\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: controller configuration timed out\n");
             return;
         }
 
         if (controller.performSelfTest()) |reply| {
             if (reply != ps2.response_controller_test_passed) {
-                _ = runtime.system.write("system/drivers/ps2-bus: perform controller self test failed\n");
+                _ = runtime.system.write("/system/drivers/ps2-bus: perform controller self test failed\n");
                 return;
             }
         } else {
-            _ = runtime.system.write("system/drivers/ps2-bus: controller self test timed out\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: controller self test timed out\n");
             return;
         }
 
         has_two_channels = controller.hasTwoChannels() orelse {
-            _ = runtime.system.write("system/drivers/ps2-bus: controller channels timed out\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: controller channels timed out\n");
             return;
         };
 
         if (has_two_channels) {
-            _ = runtime.system.write("system/drivers/ps2-bus: has two channels\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: has two channels\n");
             // keep the bus quiet until we have tested the ports and are ready to use them
             controller.disablePort(.two);
         } else {
-            _ = runtime.system.write("system/drivers/ps2-bus: has one channel\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: has one channel\n");
         }
 
         // interface tests: always test port 1, test port 2 only if it exists
         const port_one_works = (controller.testPort(.one) orelse {
-            _ = runtime.system.write("system/drivers/ps2-bus: port 1 test timed out\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: port 1 test timed out\n");
             return;
         }) == ps2.response_port_test_passed;
 
         var port_two_works = false;
         if (has_two_channels) {
             port_two_works = (controller.testPort(.two) orelse {
-                _ = runtime.system.write("system/drivers/ps2-bus: port 2 test timed out\n");
+                _ = runtime.system.write("/system/drivers/ps2-bus: port 2 test timed out\n");
                 return;
             }) == ps2.response_port_test_passed;
         }
 
         if (!port_one_works and !port_two_works) {
-            _ = runtime.system.write("system/drivers/ps2-bus: no usable ports\n");
+            _ = runtime.system.write("/system/drivers/ps2-bus: no usable ports\n");
             return;
         }
 
@@ -188,16 +188,16 @@ pub fn main() void {
         // abort bring-up of the other one
         if (port_one_works) {
             if (controller.resetDevice(.one)) |passed| {
-                if (!passed) _ = runtime.system.write("system/drivers/ps2-bus: port 1 device reset failed\n");
+                if (!passed) _ = runtime.system.write("/system/drivers/ps2-bus: port 1 device reset failed\n");
             } else {
-                _ = runtime.system.write("system/drivers/ps2-bus: port 1 device reset timed out\n");
+                _ = runtime.system.write("/system/drivers/ps2-bus: port 1 device reset timed out\n");
             }
         }
         if (port_two_works) {
             if (controller.resetDevice(.two)) |passed| {
-                if (!passed) _ = runtime.system.write("system/drivers/ps2-bus: port 2 device reset failed\n");
+                if (!passed) _ = runtime.system.write("/system/drivers/ps2-bus: port 2 device reset failed\n");
             } else {
-                _ = runtime.system.write("system/drivers/ps2-bus: port 2 device reset timed out\n");
+                _ = runtime.system.write("/system/drivers/ps2-bus: port 2 device reset timed out\n");
             }
         }
 
@@ -207,13 +207,13 @@ pub fn main() void {
         if (port_one_works) port_device_types[@intFromEnum(ps2.Port.one)] = spawnIdentifiedDriver(controller, .one);
         if (port_two_works) port_device_types[@intFromEnum(ps2.Port.two)] = spawnIdentifiedDriver(controller, .two);
     } else {
-        _ = runtime.system.write("system/drivers/ps2-bus: no PS/2 controller found\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: no PS/2 controller found\n");
         return;
     }
 
     const controller = maybe_controller.?;
     const interrupt_index = maybe_interrupt_index orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus: controller is missing its IRQ\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: controller is missing its IRQ\n");
         return;
     };
 
@@ -221,11 +221,11 @@ pub fn main() void {
     // well-known id so the children can find it, the way input subscribers find
     // the input service.
     const endpoint = ipc.createIpcEndpoint() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus: no endpoint\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: no endpoint\n");
         return;
     };
     if (!ipc.register(.ps2_bus, endpoint)) {
-        _ = runtime.system.write("system/drivers/ps2-bus: register failed\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: register failed\n");
         return;
     }
 
@@ -234,7 +234,7 @@ pub fn main() void {
     // let the controller raise them — an interrupt with nobody bound is lost.
     controller.drainOutputBuffer();
     if (!device.irqBind(controller.device_id, interrupt_index, endpoint)) {
-        _ = runtime.system.write("system/drivers/ps2-bus: irq_bind failed\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: irq_bind failed\n");
         return;
     }
 
@@ -253,21 +253,21 @@ pub fn main() void {
                         .gsi = descriptor.resources[auxiliary_index].start,
                     };
                 } else {
-                    _ = runtime.system.write("system/drivers/ps2-bus: auxiliary irq_bind failed\n");
+                    _ = runtime.system.write("/system/drivers/ps2-bus: auxiliary irq_bind failed\n");
                 }
             }
         }
     }
 
     var configuration = controller.readConfigurationByte() orelse {
-        _ = runtime.system.write("system/drivers/ps2-bus: controller configuration timed out\n");
+        _ = runtime.system.write("/system/drivers/ps2-bus: controller configuration timed out\n");
         return;
     };
     if (port_device_types[@intFromEnum(ps2.Port.one)] != null) configuration |= ps2.Port.one.interruptBit();
     if (maybe_auxiliary_interrupt != null) configuration |= ps2.Port.two.interruptBit();
     _ = controller.writeConfigurationByte(configuration);
 
-    _ = runtime.system.write("system/drivers/ps2-bus: ok\n");
+    _ = runtime.system.write("/system/drivers/ps2-bus: ok\n");
 
     // The forwarding loop: an IRQ1 notification drains the output buffer, routing
     // each byte to the attached driver of the port it came from; a client message
diff --git a/system/services/acpi/acpi.zig b/system/services/acpi/acpi.zig
index 6132dfd..df8542c 100644
--- a/system/services/acpi/acpi.zig
+++ b/system/services/acpi/acpi.zig
@@ -308,9 +308,75 @@ fn onSci() void {
         _ = runtime.system.write("power: button pressed\n");
         publishButton();
     }
+    handleGpe();
     _ = device.irqAck(node_id, sci_resource_index);
 }
 
+/// General-purpose events: for each set+enabled GPE bit, evaluate its `\_GPE`
+/// handler method (`_Lxx` level / `_Exx` edge), drain the Notify queue the
+/// method produced, and publish an event per notified device. Then clear the
+/// status bit. QEMU raises no GPEs on this config, so this path is exercised by
+/// host unit tests (docs/m21-plan.md decision 5); on real hardware it carries
+/// battery/AC/lid. The embedded controller's `_Qxx` queries are out of scope.
+fn handleGpe() void {
+    handleGpeBlock(gpe0_blk, gpe0_len, 0);
+    handleGpeBlock(gpe1_blk, gpe1_len, gpe0_len * 4);
+}
+
+fn handleGpeBlock(blk: u16, len: u8, gpe_base: u32) void {
+    if (blk == 0 or len == 0) return;
+    const status_bytes = len / 2; // status half, then enable half
+    var byte_index: u8 = 0;
+    while (byte_index < status_bytes) : (byte_index += 1) {
+        const sts: u8 = @truncate(halPioRead(1, blk + byte_index));
+        const en: u8 = @truncate(halPioRead(1, blk + status_bytes + byte_index));
+        const active = sts & en;
+        if (active == 0) continue;
+        var bit: u3 = 0;
+        while (true) : (bit += 1) {
+            if (active & (@as(u8, 1) << bit) != 0) {
+                dispatchGpe(gpe_base + @as(u32, byte_index) * 8 + bit);
+            }
+            if (bit == 7) break;
+        }
+        halPioWrite(1, blk + byte_index, active); // write-1-to-clear the serviced bits
+    }
+}
+
+/// Evaluate the `\_GPE._L%02X` or `_E%02X` handler for GPE number `n`, then
+/// publish an event for each device it notified.
+fn dispatchGpe(n: u32) void {
+    const gpe_scope = aml.Namespace.resolve(&persistent_namespace, persistent_namespace.root, true, 0, &.{seg4("_GPE")}) orelse return;
+    var name: [4]u8 = .{ '_', 'L', 0, 0 };
+    writeHex2(name[2..4], n);
+    var method = aml.Namespace.childOf(gpe_scope, name);
+    if (method == null) {
+        name[1] = 'E';
+        method = aml.Namespace.childOf(gpe_scope, name);
+    }
+    const m = method orelse return; // no handler — the status bit was already cleared
+    _ = global_interpreter.evaluate(m, &.{}) catch return;
+    for (global_interpreter.takeNotifications()) |event| publishNotify(event.node, event.code);
+}
+
+fn publishNotify(node: *aml.Node, code: u64) void {
+    // Map the notified device's _HID to a domain event where we recognize it.
+    var hid: [8]u8 = .{0} ** 8;
+    if (readHid(node, &global_interpreter)) |h| hid = h;
+    const which: power.Event = if (std.mem.eql(u8, hid[0..7], "PNP0C0A")) .battery else if (std.mem.eql(u8, hid[0..7], "ACPI0003")) .ac else if (std.mem.eql(u8, hid[0..7], "PNP0C0D")) .lid else .notify;
+    var event = power.EventMessage{ .event = @intFromEnum(which), .code = @truncate(code) };
+    event.hid = hid;
+    writeLine("power: notify {s} code {d}\n", .{ hid[0..7], code });
+    publishEvent(std.mem.asBytes(&event));
+}
+
+/// Two lowercase hex digits of `n` into `out[0..2]`.
+fn writeHex2(out: []u8, n: u32) void {
+    const digits = "0123456789ABCDEF";
+    out[0] = digits[(n >> 4) & 0xF];
+    out[1] = digits[n & 0xF];
+}
+
 fn publishButton() void {
     const event = power.EventMessage{ .event = @intFromEnum(power.Event.power_button) };
     publishEvent(std.mem.asBytes(&event));