81 lines
3.5 KiB
Zig
81 lines
3.5 KiB
Zig
//! /system/services/device-manager — the ring-3 process that turns the device
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//! tree into a running system. The kernel enumerates the hardware and enforces the
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//! claim capability (mechanism); this decides *which driver serves which device*
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//! and, eventually, spawns it (policy). Keeping that split in user space is the
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//! whole point of the microkernel: the manager is an ordinary, restartable process
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//! with no special privilege — it uses the same `device_*` system calls any process
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//! could ([drivers.md](../../../docs/drivers.md), [driver-model.md]).
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//!
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//! Increment 2 (this file): enumerate /system/devices, *match* each device to a
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//! driver, and *spawn* it with `system_spawn` — the kernel loads the named binary
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//! from the initial-ramdisk as a fresh ring-3 process. On QEMU this discovers the
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//! HPET, decides `hpet` serves it, and brings that driver all the way up. (The
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//! kernel still auto-spawns the whole initial-ramdisk at boot; increment 3 removes
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//! that redundancy so the manager is the sole owner of driver spawning.)
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const std = @import("std");
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const runtime = @import("runtime");
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const acpi_ids = @import("acpi-ids");
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const device = runtime.device;
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const system = runtime.system;
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/// Format one whole log line and emit it in a single `debug_write`, so output
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/// from the drivers this manager starts (which run concurrently) can never land
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/// in the middle of it.
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fn writeLine(comptime fmt: []const u8, arguments: anytype) void {
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var line: [128]u8 = undefined;
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_ = runtime.system.write(std.fmt.bufPrint(&line, fmt, arguments) catch return);
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}
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/// The driver that serves each device — the policy table. In a fuller system
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/// this comes from the drivers describing what they bind (or a manifest under
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/// /system/drivers); for now it is a small static map, which is enough to prove the
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/// manager reads the tree and decides. `null` = no driver for this class yet.
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fn driverFor(d: device.DeviceDescriptor) ?[]const u8 {
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// detect device via DeviceClass
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if (d.class == @intFromEnum(device.DeviceClass.timer)) return "hpet";
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// detect device via hid
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const hid = d.hid[0..@intCast(d.hid_len)];
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const id = acpi_ids.HardwareId.fromHid(hid) orelse return null;
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return switch (id) {
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.ps2_keyboard, .ps2_mouse => "ps2-bus",
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else => null,
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};
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}
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pub fn main() void {
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// Enumerate into a heap buffer (too big for the one-page user stack).
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const buffer = runtime.allocator().alloc(device.DeviceDescriptor, 64) catch {
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_ = runtime.system.write("device-manager: out of memory\n");
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return;
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};
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const total = device.enumerate(buffer);
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const count = @min(total, buffer.len);
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var matched: usize = 0;
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for (buffer[0..count]) |descriptor| {
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const driver_name = driverFor(descriptor) orelse continue;
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matched += 1;
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if (!system.isProcessRunning(driver_name)) {
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if (runtime.system.spawn(driver_name) != null) {
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writeLine("device-manager: spawned {s}\n", .{driver_name});
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} else {
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writeLine("device-manager: failed to spawn {s}\n", .{driver_name});
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}
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} else {
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writeLine("device-manager: already spawned {s}\n", .{driver_name});
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}
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}
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if (matched == 0) {
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_ = runtime.system.write("device-manager: no matchable devices\n");
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return;
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}
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_ = runtime.system.write("device-manager: ok\n");
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while (true) runtime.system.sleep(1000);
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}
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pub const panic = runtime.panic;
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comptime {
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_ = &runtime.start._start; // pull the runtime entry shim into the image
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}
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