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

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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				@@ -8,8 +8,9 @@ without a human staring at the screen.

				There are two layers:

				- **Host unit tests** (`zig build test`) — for pure, platform-independent logic in

				  the shared `system` module (the handoff layout in `system/system.zig`). These compile

				  for the host and run natively.

				  the shared contracts (`system/boot-handoff.zig`, `system/abi.zig`,

				  `system/devices/device-abi.zig`), which also compile-checks the three-way split

				  stays self-consistent. These compile for the host and run natively.

				- **QEMU integration tests** (`python3 test/qemu_test.py`) — boot the real kernel

				  and check its behaviour. This is the interesting part.

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

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