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Split the system contract into boot-handoff / abi / device-abi

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The `system` module (formerly `danos`) had become a grab-bag: it held the
loader<->kernel handoff *and* the kernel<->user ABI *and* the device wire types, in
one module three different audiences imported. Usage proved the seam — the
bootloader never touched the syscall/device ABI, and user space never touched the
boot handoff — so split it by audience, one module per contract:

  system/boot-handoff.zig       loader <-> kernel: BootInformation, Framebuffer,
                                MemoryMap, the VM layout + physicalToVirtual, kernel_abi
  system/abi.zig                kernel <-> user, core: SystemCall, mmap prot flags,
                                page_size, notify_badge_bit, ServiceId
  system/devices/device-abi.zig kernel <-> user, devices: DeviceDescriptor,
                                DeviceClass, ResourceDescriptor, ResourceKind, ...

device-abi is the devices sub-project's public interface, exposed as its own module
the way vfs exposes vfs-protocol — importable by user space, unlike the
kernel-internal device model it also feeds. That collapses a real duplication:
DeviceClass and ResourceKind were defined twice (device-model.zig and the contract,
kept "in sync by hand"); device-model now re-exports them from device-abi, so the
enum a driver matches on and the one the kernel classifies with are one type.

Each import now declares which contract it speaks: the bootloader imports only
boot-handoff; a driver only abi + device-abi (via the runtime); the kernel all
three. This also retires the `system` / `runtime.system` name overlap. page_size
lands in abi (it's part of the mmap contract user space aligns to); the bootloader
keeps its own local 4 KiB constant so it depends on nothing but the handoff.

All 21 importers rewired, docs updated to keep /system mapping to source. Build,
host tests, and the QEMU suite (36/36) all green.
This commit is contained in:
Daniel Samson
2026-07-10 18:08:51 +01:00
parent 47610e8ee2
commit be81394be3
37 changed files with 395 additions and 337 deletions
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library/runtime/system.zig
+5 -5
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@@ -1,15 +1,15 @@
//! Typed system_call surface for user space — thin wrappers over the raw `system_call`
//! stubs, one per kernel call. Numbers come from `system.SystemCall`, the single
//! stubs, one per kernel call. Numbers come from `abi.SystemCall`, the single
//! source of truth shared with the kernel dispatcher.
const system = @import("system");
const abi = @import("abi");
const sc = @import("system-call.zig");
/// `mmap` protection flags (matching the usual C bit values). Grants are always
/// readable+writable today; the kernel does not yet honour finer prot.
pub const PROT_READ: usize = system.prot_read;
pub const PROT_WRITE: usize = system.prot_write;
pub const PROT_EXEC: usize = system.prot_exec;
pub const PROT_READ: usize = abi.prot_read;
pub const PROT_WRITE: usize = abi.prot_write;
pub const PROT_EXEC: usize = abi.prot_exec;
/// Give up the rest of this quantum.
pub fn yield() void {