Files
danos/lib/vfs-protocol.zig
T
Daniel Samson 15b70856c9 M11–M12: IRQ-as-IPC and bus drivers; expand names tree-wide
Two driver-model milestones plus a tree-wide naming pass. Suite 35/35
(QEMU) + host tests green.

M11 — IRQ-as-IPC. A ring-3 driver now sleeps until its device interrupts
it. New src/kernel/irq.zig: per-GSI endpoint bindings, comptime per-vector
trampolines, dispatch = mask GSI -> LAPIC EOI -> notifyLocked, all under one
lock region. irq_bind/irq_ack syscalls, gated by the device claim like
mmio_map. interruptDispatch no longer EOIs — each handler owns its EOI,
because a level line must be masked before it is acknowledged (irq_ack is
the unmask). Bindings are keyed on the owning task and released on exit
(a shared endpoint's siblings survive). hpetd rewritten interrupt-driven.
Tests: hpet (rewritten, reads back the I/O APIC routing) and irqfree.

M12 — bus drivers. DeviceDesc gains a parent, making the device table a
tree. dev_register (device_register) lets a process publish children below
a device it claimed; the kernel enforces resource containment (a child's
resources must nest in its parent's), so a descriptor can't fabricate a
window over kernel RAM. Descriptor copied in via copyFromUser (physmap
walk — an unmapped user pointer fails the call instead of faulting the
kernel). Per-parent child cap bounds table exhaustion. sbin/busd.zig is a
worked bus driver. Test: bus.

Naming — per docs/coding-standards.md: non-acronym abbreviations spelled
out (message, descriptor, device_service, scheduler, runtime, physical,
interpreter, ...); acronyms kept (IPC, MMIO, DMA, HCD, ...); files are
kebab-case (ipc-synchronous.zig, device-service.zig, vfs-protocol.zig, ...).
Exceptions: POSIX/C ABI names and Zig idioms (init/len/ptr) kept. Module
collisions resolved by specific naming (config -> parameters, device.zig
alias -> device_model). AML op/Op disambiguated: op = opcode, Op =
operation; per-opcode parse handlers renamed opX -> parseX.

New driver docs: drivers.md, driver-model.md (bus/class/HCD shapes + the
proposed M13–M16 ABI), coding-standards.md.
2026-07-10 11:39:56 +01:00

54 lines
1.8 KiB
Zig

//! The VFS wire protocol — the message format spoken between a client (via the
//! `runtime` file API) and the user-space VFS server over IPC. A request is a fixed
//! `Request` header followed by an inline payload (a path, or write bytes); a
//! reply is a fixed `Reply` header followed by an inline payload (read bytes, or
//! a Stat). Everything fits in one IPC message (<= ipc MESSAGE_MAXIMUM = 256 bytes).
//!
//! This is user-space only — the kernel knows nothing of files or paths; it only
//! moves the bytes. Shared by lib/unistd.zig (client) and sbin/vfs.zig (server).
pub const Op = enum(u32) {
open, // open(path) -> node id
close, // close(node)
read, // read(node, offset, len) -> bytes
write, // write(node, offset, bytes) -> count
stat, // stat(node) -> Stat
};
/// Request header. `node` is the server-side open-file id (from a prior open);
/// for `open` the path is the payload and `len` is its length. `offset`/`len`
/// carry the read/write position and count.
pub const Request = extern struct {
op: Op,
node: u64,
offset: u64,
len: u32,
flags: u32,
};
/// Reply header. `status` is 0 on success or a negative errno; `node` is the new
/// open-file id (for `open`); `len` is the payload length (bytes read, or the
/// Stat size).
pub const Reply = extern struct {
status: i32,
_pad: u32 = 0,
node: u64 = 0,
len: u32 = 0,
_pad2: u32 = 0,
};
pub const Stat = extern struct {
size: u64,
kind: u32,
_pad: u32 = 0,
};
pub const message_maximum: usize = 256;
pub const req_size: usize = @sizeOf(Request);
pub const reply_size: usize = @sizeOf(Reply);
/// Largest inline payload that still fits one IPC message alongside a header.
pub const maximum_payload: usize = message_maximum - req_size;
/// Open flags.
pub const O_CREAT: u32 = 1;