Files
danos/system/parameters.zig
Daniel Samson 3fb9d5936a USB driver stack: xHCI transfers, HID keyboard/mouse, mass storage
Flesh out the xHCI host-controller driver into a full transfer engine and build
the three USB class drivers on top, all verified end to end under QEMU.

- xHCI engine (usb-xhci-library.zig): controller reset, command/event rings with
  cycle-bit bookkeeping (gated on a No-Op-command proof), device slots, Address
  Device, control transfers, full chapter-9 enumeration, Configure Endpoint, and
  interrupt/bulk transfers. Each interface is device_registered with its
  (class,subclass,protocol) identity, unique per (port,interface).
- Bus<->class transfer protocol (usb-transfer-protocol.zig + runtime.usb): open /
  control / interrupt-subscribe (async report pump on a poll timer) / bulk-by-
  physical-address, so sector data never crosses the 256-byte IPC limit.
- USB HID keyboard + mouse (usb-hid/): decode boot-protocol reports and publish
  to the input service. A USB usage is already the input protocol's keycode.
- USB mass storage (usb-storage/): Bulk-Only Transport + transparent SCSI,
  serving a block device under the new .block service id (block-protocol).
- device-manager matches USB interfaces to class drivers (usbDriverForIdentity).
- usb-abi / usb-ids made importable modules; add HID and mass-storage class
  requests, packTriple, and a usb_device DeviceClass.
- Fix test/qemu_test.py on macOS: the QMP unix-socket path was built from the
  deep worktree path and exceeded the 104-byte sun_path limit, so QEMU exited
  before booting. It now lives under a short temp path.

Tests: usb-report, usb-hid, usb-storage pass under python3 test/qemu_test.py;
host units (usb-abi, usb-ids, hid-report, bulk-only-transport, scsi) green.
2026-07-13 14:11:00 +01:00

43 lines
2.4 KiB
Zig

//! Kernel tunables — the compile-time knobs, gathered in one place.
//!
//! These constants would otherwise be scattered across the files that use them,
//! hiding the trade-offs. Keeping them here makes them visible at a glance and gives
//! one spot to change them. They're plain `comptime` constants (zero runtime cost);
//! any one can later be promoted to a `-D` build option if a target needs to vary it
//! (see build.zig's `-Dtest-case` for the pattern). This keeps ps2-library.zig to what it
//! actually is — the bootloader↔kernel handoff *contract* — with tunables living here.
/// Ceiling on logical CPUs the kernel tracks — the size of the per-CPU bookkeeping
/// arrays (discovery pool, scheduler state, per-core GDT/TSS). Generous headroom:
/// those structs are small, and the *large* per-core resources (kernel and IST
/// stacks) are allocated at bring-up for cores that actually come online, so this
/// ceiling is cheap. A machine with more logical CPUs has its surplus reported and
/// left parked (see acpi `cpusDropped`).
pub const maximum_cpus = 128;
/// Maximum tasks (kernel threads) alive at once — the static task-table size. Each
/// online core consumes one slot for its idle task, plus task 0 on the BSP. Sized
/// for the initial-ramdisk sweep (the bundled binaries spawned at once) plus the
/// device manager's supervised children with room to grow — at 16 the sweep
/// started failing spawns once the bundle passed a dozen binaries. Raised to 48
/// for the USB stack: the xHCI bus driver spawns a supervised class-driver instance
/// per matched interface (keyboard, mouse, mass storage), on top of the FAT and
/// block servers and the growing ramdisk bundle.
pub const maximum_tasks = 48;
/// Each task's kernel stack (also each AP's bring-up stack), in bytes.
pub const kernel_stack_size = 16 * 1024;
/// Each user process's stack, in pages (32 KiB). Mapped just below a fixed top;
/// the System V entry block (argc/argv) occupies the top of the highest page, and
/// the page below the mapping is left unmapped as a guard, so an overflow faults
/// (killing only that process) instead of silently corrupting the image.
pub const user_stack_pages = 8;
/// Each core's IST (double-fault) stack, in bytes. The BSP's is static; an AP's is
/// heap-allocated at bring-up.
pub const ist_stack_size = 16 * 1024;
/// Scheduler tick / preemption rate, in Hz (the timer's periodic frequency).
pub const timer_hz = 1000;