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README.md
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@@ -63,7 +63,7 @@ zig build release-x86-64
Produces `zig-out/danos-x86-64.iso`, a hybrid ISO that boots flashed raw to a
USB stick (balenaEtcher, dd) or burned to optical media — see
[docs/release-iso.md](docs/os-development-guide/release-iso.md). `zig build check-iso-image`
[docs/release-iso.md](docs/os-development/release-iso.md). `zig build check-iso-image`
validates it without booting.
## Run
docs/README.md
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@@ -3,102 +3,102 @@
Notes on how danos boots and draws, written to explain the *why* behind the code
rather than restate it. Roughly in the order things happen at runtime:
1. **[efi.md](os-development-guide/efi.md) — EFI / the boot process.** How UEFI firmware finds and
1. **[efi.md](os-development/efi.md) — EFI / the boot process.** How UEFI firmware finds and
runs the bootloader, what the loader gathers before `ExitBootServices`, how it
loads the kernel ELF, and the ABI contract for the jump into the kernel. Start
here.
2. **[system-image.md](os-development-guide/system-image.md) — system.img, the boot capsule.** The
2. **[system-image.md](os-development/system-image.md) — system.img, the boot capsule.** The
bundled user binaries packed into one file in the initial-ramdisk wire
format, because one open + one sequential read is the only file I/O shape
firmware is fast at. The trivial container format, the three artifacts one
build list derives (tree, manifest, capsule), the loader's three-strategy
fallback chain, and the capsule's kernel-side life as both the spawn table
and the read-only `/system` mount.
3. **[gop.md](os-development-guide/gop.md) — the Graphics Output Protocol.** How UEFI exposes graphics
3. **[gop.md](os-development/gop.md) — the Graphics Output Protocol.** How UEFI exposes graphics
modes (unlike fixed VGA modes), how we detect the monitor's native resolution
from EDID and switch to it, and the pixel formats we accept or reject.
4. **[framebuffer.md](os-development-guide/framebuffer.md) — the framebuffer.** What the linear
4. **[framebuffer.md](os-development/framebuffer.md) — the framebuffer.** What the linear
framebuffer the loader hands over actually is, and what **pitch** (stride)
means versus width — the detail you have to get right to avoid a skewed image.
5. **[memory-map.md](os-development-guide/memory-map.md) — the memory map.** How the loader learns what
5. **[memory-map.md](os-development/memory-map.md) — the memory map.** How the loader learns what
physical RAM exists and hands it to the kernel in danos's own neutral format,
rather than leaking UEFI's memory descriptors across the boundary.
6. **[frame-allocator.md](os-development-guide/frame-allocator.md) — the physical frame allocator.** The
6. **[frame-allocator.md](os-development/frame-allocator.md) — the physical frame allocator.** The
bitmap allocator that hands out and reclaims 4 KiB physical frames from that
map — the primitive page tables and the heap are built on.
7. **[interrupts.md](os-development-guide/interrupts.md) — interrupts and exceptions.** The GDT, IDT and
7. **[interrupts.md](os-development/interrupts.md) — interrupts and exceptions.** The GDT, IDT and
TSS, the exception stubs, and the handler that reports a CPU fault in red instead
of letting it triple-fault into a silent reset.
8. **[paging.md](os-development-guide/paging.md) — the kernel's page tables.** Building our own 4-level
8. **[paging.md](os-development/paging.md) — the kernel's page tables.** Building our own 4-level
page tables, identity-mapping the low 4 GiB, and switching CR3 off the firmware's
tables onto ours.
9. **[device-interrupts.md](device-driver-development-guide/device-interrupts.md) — device interrupts.** The Local
9. **[device-interrupts.md](device-driver-development/device-interrupts.md) — device interrupts.** The Local
APIC and its timer — the kernel's first interrupt that is *handled and returned
from*, giving it a heartbeat.
10. **[heap.md](os-development-guide/heap.md) — the kernel heap.** A growable free-list allocator built on
10. **[heap.md](os-development/heap.md) — the kernel heap.** A growable free-list allocator built on
the VMM, exposed as a `std.mem.Allocator` so std containers work — dynamic
allocation for the kernel.
11. **[scheduling.md](os-development-guide/scheduling.md) — the scheduler.** Fixed-priority preemptive
11. **[scheduling.md](os-development/scheduling.md) — the scheduler.** Fixed-priority preemptive
multitasking: kernel threads, the context switch, O(1) priority selection, and
blocking (sleep, wait queues) — the leap to a running system.
12. **[ipc.md](device-driver-development-guide/ipc.md) — inter-process communication.** Bounded blocking
12. **[ipc.md](device-driver-development/ipc.md) — inter-process communication.** Bounded blocking
message-passing channels, then synchronous call/reply between *processes* over
endpoints — the backbone the microkernel's isolated servers talk over.
13. **[syscall.md](os-development-guide/syscall.md) — system calls.** How ring 3 asks the kernel for
13. **[syscall.md](os-development/syscall.md) — system calls.** How ring 3 asks the kernel for
something: the `syscall`/`sysret` fast path, the trap frame, and why the table is
deliberately tiny. The numbers are a **private** ABI — [vdso.md](os-development-guide/vdso.md) designs
deliberately tiny. The numbers are a **private** ABI — [vdso.md](os-development/vdso.md) designs
the public boundary that will hide them.
14. **[vfs-protocol.md](file-system-development/vfs-protocol.md) — the VFS wire protocol.** The language-neutral
byte-level spec of the file protocol spoken over IPC: request/reply headers,
the operation table, mount routing, and the append-only evolution rules — the
first IPC protocol documented as public ABI.
15. **[drivers.md](device-driver-development-guide/drivers.md) — writing a driver.** The payoff: a driver is an
15. **[drivers.md](device-driver-development/drivers.md) — writing a driver.** The payoff: a driver is an
ordinary ring-3 process that claims a device, maps its registers, and **sleeps
until its hardware interrupts it**. The claim is the capability; `irq_ack` is the
unmask.
16. **[driver-model.md](device-driver-development-guide/driver-model.md) — buses, classes and host controllers.** How
16. **[driver-model.md](device-driver-development/driver-model.md) — buses, classes and host controllers.** How
real driver stacks factor into three shapes and how families share code. The
three primitives it proposed are long since built (M13 capability passing,
M14 DMA + barriers, M15 MSI), and the driver *contract* on top of them —
hello, supervision, restart — is built too (device-manager.md, M18).
17. **[usb-hub.md](device-driver-development-guide/usb-hub.md) — USB hubs.** Built (M22): why hub topology is handled
17. **[usb-hub.md](device-driver-development/usb-hub.md) — USB hubs.** Built (M22): why hub topology is handled
*inside* the `usb-xhci-bus` driver rather than a separate hub class driver — a
device behind a hub is reached by the **controller**, programmed with a route
string in its slot context — plus the compound-hub reality (a USB 3.0 hub is
physically two hubs) and detection via the hub's status-change interrupt endpoint.
18. **[process-management.md](os-development-guide/process-management.md) — process management.** The
18. **[process-management.md](os-development/process-management.md) — process management.** The
microkernel's `ps`/`kill`/SIGCHLD: enumerate as a table snapshot, the
supervision link as the kill authority, and child-exit notifications over the
same endpoints IRQs arrive on.
19. **[process-lifecycle.md](os-development-guide/process-lifecycle.md) — the process lifecycle.** Built
19. **[process-lifecycle.md](os-development/process-lifecycle.md) — the process lifecycle.** Built
(M17): signals over IPC as the one lifecycle vocabulary every process speaks — the
POSIX.1-1990 words with message delivery instead of stack hijack, the stable
`process` module interface, exit reasons, published exit events any stateful
service can subscribe to (the VFS releasing dead clients' handles), and the two
iron rules (cleanup is the kernel's job; kill is not a signal).
20. **[device-manager.md](device-driver-development-guide/device-manager.md) — the device manager.** Built (M18,
20. **[device-manager.md](device-driver-development/device-manager.md) — the device manager.** Built (M18,
through the app surface): the
tree, the matcher, and the supervisor. Tree structure lives in the manager,
authority stays in the kernel; bus drivers report what they see; drivers are
restarted through the lifecycle vocabulary — the plan that turns
[resilience.md](os-development-guide/resilience.md)'s restart goal into increments.
21. **[input.md](device-driver-development-guide/input.md) — the input module.** Broadcasting input events (keyboard,
[resilience.md](os-development/resilience.md)'s restart goal into increments.
21. **[input.md](device-driver-development/input.md) — the input module.** Broadcasting input events (keyboard,
mouse, joystick): why a synchronous rendezvous can't fan out to many listeners, the
asynchronous `ipc_send` primitive built to fix it, and the per-device subscribe/publish
service layered on top.
22. **[display.md](device-driver-development-guide/display.md) — the display service.** The display half of the GUI
22. **[display.md](device-driver-development/display.md) — the display service.** The display half of the GUI
track: a user-space compositor that owns the framebuffer, composes a layer stack into
a double buffer, and presents it. Why GOP and the PCI display device are two views of
one controller, the device-node + write-combining handoff, and what flicker-free buys
that tear-free doesn't. Plan: [display-plan.md](device-driver-development-guide/display-plan.md). **v2** (complete) makes
that tear-free doesn't. Plan: [display-plan.md](device-driver-development/display-plan.md). **v2** (complete) makes
scanout a pluggable backend — GOP floor + a native virtio-gpu driver, hot-attached, with
runtime mode-set, EDID, fenced vsync presents, and restart re-attach:
[display-v2.md](device-driver-development-guide/display-v2.md), plan [display-v2-plan.md](device-driver-development-guide/display-v2-plan.md). Looking
[display-v2.md](device-driver-development/display-v2.md), plan [display-v2-plan.md](device-driver-development/display-v2-plan.md). Looking
further out, three research snapshots survey what a *native* driver for real GPU silicon
would take as another `.scanout` backend: [nvidia-gpus.md](device-driver-development-guide/nvidia-gpus.md) (RTX 3060 /
Ampere), [amd-gpus.md](device-driver-development-guide/amd-gpus.md) (RX 6600 / RDNA2), and [intel-igpu.md](device-driver-development-guide/intel-igpu.md)
would take as another `.scanout` backend: [nvidia-gpus.md](device-driver-development/nvidia-gpus.md) (RTX 3060 /
Ampere), [amd-gpus.md](device-driver-development/amd-gpus.md) (RX 6600 / RDNA2), and [intel-igpu.md](device-driver-development/intel-igpu.md)
(Intel iGPU).
23. **[halting.md](os-development-guide/halting.md) — halting.** Why a kernel can't just "exit", and
23. **[halting.md](os-development/halting.md) — halting.** Why a kernel can't just "exit", and
how `while (true) hlt` parks the CPU safely once there's nothing left to do.
Start with the north star:
@@ -108,7 +108,7 @@ Start with the north star:
**resilience** (restartable components). Win condition: runs on the author's PC and
both Raspberry Pis, ideally with a GUI. Real-time is an option to explore, not a
requirement. The *why* that shapes everything below.
- **[resilience.md](os-development-guide/resilience.md) — resilience.** A design note (not built yet) on
- **[resilience.md](os-development/resilience.md) — resilience.** A design note (not built yet) on
fault isolation + live restart — the reincarnation-server + capability model that
makes "if I break it, I can restart it" real. danos's core motivation.
- **[zig-self-hosting.md](zig-self-hosting.md) — running Zig on danos.** A design note
@@ -117,14 +117,14 @@ Start with the north star:
port to **one seam** (`std.os.danos`), so we build an `os` seam module (→ that seam) plus
the thin `file-system` module, retire the `posix` shim, and follow a phased path to
`zig build-exe hello.zig` running on danos — **not** Linux-ABI emulation.
- **[threading.md](os-development-guide/threading.md) — threads, the std-shaped way.** **Built** (M1–M6):
- **[threading.md](os-development/threading.md) — threads, the std-shaped way.** **Built** (M1–M6):
the `thread` module's `Thread` mirrors `std.Thread`'s API (spawn/join/detach, Mutex/Condition/
Semaphore) over a **private** thread ABI — several tasks sharing one address space via
a `thread_spawn` syscall, futex-backed blocking, address-space refcounting. Why it's the
native type and not literal `std.Thread` (the [private ABI](os-development-guide/syscall.md)), and why
threads stay a narrow opt-in against the [resilience](os-development-guide/resilience.md) default. Build
plan + gates: [threading-plan.md](os-development-guide/threading-plan.md).
- **[vdso.md](os-development-guide/vdso.md) — the vDSO, the public system-call boundary.** A design note
native type and not literal `std.Thread` (the [private ABI](os-development/syscall.md)), and why
threads stay a narrow opt-in against the [resilience](os-development/resilience.md) default. Build
plan + gates: [threading-plan.md](os-development/threading-plan.md).
- **[vdso.md](os-development/vdso.md) — the vDSO, the public system-call boundary.** A design note
(not built yet) on keeping `abi.zig` genuinely private: a kernel-supplied, C-ABI
entry blob mapped into every process as the *only* way into the kernel — so the
syscall numbers can be renumbered or randomised at will, and Rust/C binaries get a
@@ -137,69 +137,69 @@ Cutting across all of these:
hardware needed to run danos: minimum specs (UEFI x86-64, ACPI, PCIe ECAM,
xHCI, ~128 MiB RAM) grounded in what the boot path actually assumes, plus a
plain-language guide matching Intel/AMD CPU generations by name.
- **[release-iso.md](os-development-guide/release-iso.md) — the release ISO.** The flashable boot
- **[release-iso.md](os-development/release-iso.md) — the release ISO.** The flashable boot
media: `zig build release-x86-64` wraps the FAT32 boot volume in a hybrid ISO
(MBR ESP partition + El Torito EFI entry, one embedded image) that Etcher/dd
flash to USB or a burner writes to disc — built by an in-repo pure-Python
tool, like the FAT image itself.
- **[architecture.md](os-development-guide/architecture.md) — the architecture split.** How CPU-specific code is kept
- **[architecture.md](os-development/architecture.md) — the architecture split.** How CPU-specific code is kept
behind a build-time `arch` module so the generic kernel never names x86_64,
leaving room for other systems (e.g. an AArch64 Raspberry Pi) later.
- **[arm.md](os-development-guide/arm.md) — ARM targets.** The Raspberry Pi landscape the arch split is
- **[arm.md](os-development/arm.md) — ARM targets.** The Raspberry Pi landscape the arch split is
aiming at: `arm` (32-bit, Pi Zero W) vs `aarch64` (64-bit, Pi 3-5), UEFI vs
device-tree boot, and what each layer needs.
- **[discovery.md](os-development-guide/discovery.md) — device discovery.** A design note on learning what
- **[discovery.md](os-development/discovery.md) — device discovery.** A design note on learning what
hardware exists via ACPI (x86) or device tree (ARM) behind one neutral device model —
when to build it, and how to keep it architecture-agnostic.
- **[acpi.md](os-development-guide/acpi.md) — finding the ACPI tables.** The concrete x86 locator chain:
- **[acpi.md](os-development/acpi.md) — finding the ACPI tables.** The concrete x86 locator chain:
how the loader captures the **RSDP**, hands its physical address across in `BootInformation`,
and how the platform derives the **RSDT/XSDT** from it and walks the SDTs — plus the
live event side (the SCI, the power button, GPE/Notify) the ring-3 acpi service runs.
- **[power.md](os-development-guide/power.md) — the power service.** System power as a domain-named
- **[power.md](os-development/power.md) — the power service.** System power as a domain-named
service: button/lid/battery events published to subscribers, and init's orderly
shutdown composing the [lifecycle](os-development-guide/process-lifecycle.md) stop sequence with an ACPI
shutdown composing the [lifecycle](os-development/process-lifecycle.md) stop sequence with an ACPI
S5 write. Firmware-neutral — a PSCI backend drops in on ARM.
- **[timers.md](os-development-guide/timers.md) — timers and time.** The ring-3 surface for reading the
- **[timers.md](os-development/timers.md) — timers and time.** The ring-3 surface for reading the
clock and waiting: why `now()` is a syscall rather than a service, and the one-shot
timer notification (`timer_bind`) that gives supervisors a timed wait — built on the
LAPIC heartbeat and calibrated TSC of [device-interrupts.md](device-driver-development-guide/device-interrupts.md).
- **[smp.md](os-development-guide/smp.md) — multiple cores.** A design/research note on how microkernels
LAPIC heartbeat and calibrated TSC of [device-interrupts.md](device-driver-development/device-interrupts.md).
- **[smp.md](os-development/smp.md) — multiple cores.** A design/research note on how microkernels
(L4, seL4) handle SMP — big kernel lock vs per-CPU vs multikernel — and how the
right choice depends on whether danos is chasing real-time or resilience.
- **[coding-standards.md](coding-standards.md) — coding standards.** The naming rule the
tree follows: non-acronyms are spelled out in full (`message`, not `msg`), files are
`kebab-case`, code follows Zig's case conventions, and the handful of exceptions
(POSIX/C ABI names, `init`/`len`/`ptr`, acronyms).
- **[sysv.md](os-development-guide/sysv.md) — the calling convention.** What "the kernel is SysV" means,
- **[sysv.md](os-development/sysv.md) — the calling convention.** What "the kernel is SysV" means,
and why the loader→kernel boundary has to pin it (the RDI-vs-RCX handoff).
- **[testing.md](testing.md) — testing.** How the kernel is tested by booting it in
QEMU and asserting on its serial output — reproducibly, and structured so the
same tests run across architectures.
- **[logging.md](os-development-guide/logging.md) — logging.** The multi-sink diagnostic log (serial,
- **[logging.md](os-development/logging.md) — logging.** The multi-sink diagnostic log (serial,
0xE9 debugcon, file later) kept separate from the framebuffer display, plus the
robustness path: optional framebuffer, POST-code checkpoints, and a persistent
panic breadcrumb so the kernel survives — and can be diagnosed — with no output.
## How the pieces relate
The boot flow ties them together: UEFI runs the loader ([efi.md](os-development-guide/efi.md)), which
queries the **GOP** to pick a graphics mode ([gop.md](os-development-guide/gop.md)), hands the kernel a
**framebuffer** to draw into ([framebuffer.md](os-development-guide/framebuffer.md)) and a **memory
map** of physical RAM ([memory-map.md](os-development-guide/memory-map.md)); the kernel turns that map
into a **frame allocator** ([frame-allocator.md](os-development-guide/frame-allocator.md)), installs
its **descriptor tables** so CPU faults are caught ([interrupts.md](os-development-guide/interrupts.md)),
builds its own **page tables** and switches onto them ([paging.md](os-development-guide/paging.md)),
brings up the **heap** for dynamic allocation ([heap.md](os-development-guide/heap.md)), starts the
**scheduler** ([scheduling.md](os-development-guide/scheduling.md)) and the **timer** that preempts it
([device-interrupts.md](device-driver-development-guide/device-interrupts.md)) — with tasks blocking, sleeping and
passing messages over **[IPC](device-driver-development-guide/ipc.md)** channels — runs, its CPU-specific bits
behind the [architecture](os-development-guide/architecture.md) boundary, and when idle, or on a panic, it **halts**
([halting.md](os-development-guide/halting.md)).
The boot flow ties them together: UEFI runs the loader ([efi.md](os-development/efi.md)), which
queries the **GOP** to pick a graphics mode ([gop.md](os-development/gop.md)), hands the kernel a
**framebuffer** to draw into ([framebuffer.md](os-development/framebuffer.md)) and a **memory
map** of physical RAM ([memory-map.md](os-development/memory-map.md)); the kernel turns that map
into a **frame allocator** ([frame-allocator.md](os-development/frame-allocator.md)), installs
its **descriptor tables** so CPU faults are caught ([interrupts.md](os-development/interrupts.md)),
builds its own **page tables** and switches onto them ([paging.md](os-development/paging.md)),
brings up the **heap** for dynamic allocation ([heap.md](os-development/heap.md)), starts the
**scheduler** ([scheduling.md](os-development/scheduling.md)) and the **timer** that preempts it
([device-interrupts.md](device-driver-development/device-interrupts.md)) — with tasks blocking, sleeping and
passing messages over **[IPC](device-driver-development/ipc.md)** channels — runs, its CPU-specific bits
behind the [architecture](os-development/architecture.md) boundary, and when idle, or on a panic, it **halts**
([halting.md](os-development/halting.md)).
Above that line the microkernel proper begins: **discovery** ([discovery.md](os-development-guide/discovery.md),
[acpi.md](os-development-guide/acpi.md)) learns what hardware exists, ring-3 processes ask the kernel for
things through the small **[syscall](os-development-guide/syscall.md)** table, isolated servers reach each
other over IPC **endpoints** ([ipc.md](device-driver-development-guide/ipc.md)), and a **[driver](device-driver-development-guide/drivers.md)** claims
Above that line the microkernel proper begins: **discovery** ([discovery.md](os-development/discovery.md),
[acpi.md](os-development/acpi.md)) learns what hardware exists, ring-3 processes ask the kernel for
things through the small **[syscall](os-development/syscall.md)** table, isolated servers reach each
other over IPC **endpoints** ([ipc.md](device-driver-development/ipc.md)), and a **[driver](device-driver-development/drivers.md)** claims
a device, maps its registers, and sleeps until the hardware interrupts it — which is
the whole reason for the arrangement ([vision.md](vision.md)).
docs/device-driver-development-guide/amd-gpus.md → docs/device-driver-development/amd-gpus.md
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docs/device-driver-development-guide/device-interrupts.md → docs/device-driver-development/device-interrupts.md
+8 -8
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@@ -1,6 +1,6 @@
# Device interrupts
CPU exceptions ([interrupts.md](../os-development-guide/interrupts.md)) are the kernel reacting to its own
CPU exceptions ([interrupts.md](../os-development/interrupts.md)) are the kernel reacting to its own
mistakes. **Device interrupts** are the opposite: hardware asking for attention —
a timer firing, a key pressed, a packet arriving. They share the IDT, but differ
in one fundamental way: an exception here is terminal (we report and halt), while a
@@ -10,7 +10,7 @@ back — the same mechanism a scheduler will later use to preempt tasks.
The first device we bring up is the **timer**, because it's the simplest: it lives
entirely on the CPU's local interrupt controller, needing no external routing.
It's all x86_64-specific, behind the [architecture](../os-development-guide/architecture.md) boundary.
It's all x86_64-specific, behind the [architecture](../os-development/architecture.md) boundary.
## The APIC, not the PIC
@@ -53,7 +53,7 @@ a missing PIT would hang the boot):
1. **CPUID leaf 0x15** — the CPU's TSC frequency directly, needing no external timer
at all (the LAPIC is then measured against the TSC).
2. The **HPET**, discovered via ACPI (see [discovery](../os-development-guide/discovery.md) / [acpi](../os-development-guide/acpi.md)).
2. The **HPET**, discovered via ACPI (see [discovery](../os-development/discovery.md) / [acpi](../os-development/acpi.md)).
3. The **ACPI PM timer** (a fixed 3.579545 MHz counter from the FADT).
4. The **PIT** (legacy 8254, 1.193182 MHz) — last resort, and bounded so it can't hang.
@@ -100,7 +100,7 @@ values (a second socket, some firmware), so a thread migrating from a core readi
check** as each application processor comes online (`checkWarpSource`, adapted from
Linux's): the waking core and the BSP hammer a shared "highest seen" TSC under a lock,
and if either ever reads below it, the cores' TSCs are skewed. It's pairwise because APs
come up one at a time ([smp.md](../os-development-guide/smp.md)).
come up one at a time ([smp.md](../os-development/smp.md)).
**The fallback.** When the TSC fails either test — non-invariant (a bare VM such as the
default qemu64), or warped between cores — danos moves the monotonic clock onto the
@@ -160,7 +160,7 @@ A device handler is a plain `fn () void` — a timer or keyboard handler doesn't
the interrupted registers. (The stubs originally didn't save the SSE/vector
registers, so a handler couldn't use them; `isr_common` now does an
`fxsave`/`fxrstor` of the full SSE/x87 state around dispatch — see
[interrupts.md](../os-development-guide/interrupts.md).)
[interrupts.md](../os-development/interrupts.md).)
## Turning them on
@@ -168,7 +168,7 @@ Exceptions can't be masked, which is why they worked all along. Maskable device
interrupts don't fire until the CPU's interrupt flag is set — so the final step is
`sti` (`arch.enableInterrupts()`), after the APIC and timer are configured. From
that instant the kernel has a heartbeat, and its idle `hlt` loop
([halting.md](../os-development-guide/halting.md)) wakes on every tick and dozes off again.
([halting.md](../os-development/halting.md)) wakes on every tick and dozes off again.
## Verifying it
@@ -188,13 +188,13 @@ spinning in unrelated code — is the whole mechanism working end to end.
## Since (done elsewhere)
- **Preemption**: the timer handler is where the scheduler decides to switch — the
reason a *returning* interrupt matters. See [scheduling.md](../os-development-guide/scheduling.md).
reason a *returning* interrupt matters. See [scheduling.md](../os-development/scheduling.md).
- **`sleep()` / timeouts** built on the calibrated clock.
- **The I/O APIC, routed**: external device lines now reach a vector, and the
interrupt is delivered onward to a *user-space* driver as an IPC message. See
[drivers.md](drivers.md).
- **Uncacheable MMIO**: device grants are mapped `PCD|PWT` (strong-uncacheable) for
user drivers — see [paging.md](../os-development-guide/paging.md).
user drivers — see [paging.md](../os-development/paging.md).
## What's next (partly done since)
docs/device-driver-development-guide/device-manager.md → docs/device-driver-development/device-manager.md
+9 -9
View File
@@ -10,18 +10,18 @@ mirrors them and prunes a dead reporter's children, and the `usb-report`
scenario proves report → prune → respawn → re-report. The application surface is built (M18.3, 2026-07-13):
`enumerate` and `subscribe` over IPC, with `device-list` as the first client —
the manager is now the one answer to "what devices exist" for applications.
The primitives underneath are real ([process-management.md](../os-development-guide/process-management.md):
The primitives underneath are real ([process-management.md](../os-development/process-management.md):
spawn/supervise/kill/exit-notification; [driver-model.md](driver-model.md): the device
table as a capability system; [drivers.md](drivers.md): claim/map/IRQ), and the first
per-device driver spawn works (the device manager matches the xHCI controller by PCI
class and spawns `usb-xhci-bus` with the device id as argv[1]). This document designs
the rest: the device manager as **the tree, the matcher, and the supervisor** — the
policy process that turns [resilience.md](../os-development-guide/resilience.md)'s restart goal into practice
policy process that turns [resilience.md](../os-development/resilience.md)'s restart goal into practice
for drivers.
How processes stop, reload, and report their deaths is deliberately **not** in this
document: that is the universal lifecycle every danos process speaks —
[process-lifecycle.md](../os-development-guide/process-lifecycle.md), signals over IPC and the stable
[process-lifecycle.md](../os-development/process-lifecycle.md), signals over IPC and the stable
`process` interface. The device manager is that design's first serious
customer, not its owner. Its own protocol contains nothing lifecycle-shaped; a
driver is stopped, health-checked, and buried exactly like any other process.
@@ -35,7 +35,7 @@ The device tree is two things fused: *information* (what exists, how it nests) a
claims, resource containment on `device_register`, the
`mmio_map`/`irq_bind`/`msi_bind` gates — and **cleans all of it up when a process
dies** (settled; it is increment 1 of
[process-lifecycle.md](../os-development-guide/process-lifecycle.md)). The three invariants in
[process-lifecycle.md](../os-development/process-lifecycle.md)). The three invariants in
[driver-model.md](driver-model.md) stay exactly where they are. A device manager
that could mint MMIO mappings by its own say-so would be a second kernel, and a
buggy one would un-earn everything the microkernel bought.
@@ -51,7 +51,7 @@ enumeration is a **pci-bus driver**: the manager spawns it against the host brid
like any bus reports children. ACPI becomes an **acpi service** that interprets the
tables and reports the namespace. The manager only orchestrates and merges. Moving
AML interpretation out of ring 0 is its own project on its own track; nothing here
depends on when it lands. (It landed: [discovery.md](../os-development-guide/discovery.md), M19–M20.)
depends on when it lands. (It landed: [discovery.md](../os-development/discovery.md), M19–M20.)
`device_register` is **idempotent on exact match**: a re-registration with an
identical (parent, class, identity, resources) tuple returns the existing id
@@ -82,7 +82,7 @@ one world.
deadline means wrong binary, wrong protocol version, or wedged before main — apply
the stop sequence and the restart policy. Everything else lifecycle-shaped
(terminate, the common `ping` liveness call, exit reasons) arrives through
[process-lifecycle.md](../os-development-guide/process-lifecycle.md)'s vocabulary, not this protocol.
[process-lifecycle.md](../os-development/process-lifecycle.md)'s vocabulary, not this protocol.
Assignment stays argv (`usb-xhci-bus <device id>`) for now — simple, and it works.
The step after `hello` exists is delegation: the manager claims (or is granted) the
@@ -97,7 +97,7 @@ from usb-ids.zig — each bus's native language, decoded by the shared ids modul
Every driver is spawned with the manager's exit endpoint (`spawnSupervised` — built).
On a death notification:
1. **Read the reason** ([process-lifecycle.md](../os-development-guide/process-lifecycle.md) increment 2).
1. **Read the reason** ([process-lifecycle.md](../os-development/process-lifecycle.md) increment 2).
Clean exit → it meant to; don't restart. Fault or missed `hello` deadline →
restart with **backoff**, and a crash-loop cap (three fast deaths → mark failed,
stop respawning, log loudly; a later `reload` to the manager can retry).
@@ -136,7 +136,7 @@ way.
## Increments
Increments 1–4 are the lifecycle prerequisites and live in
[process-lifecycle.md](../os-development-guide/process-lifecycle.md) (claim cleanup on death, exit reasons,
[process-lifecycle.md](../os-development/process-lifecycle.md) (claim cleanup on death, exit reasons,
published exit events, signals + `process`). On top of those:
5. **device-manager-protocol**: `hello`, supervised spawn with restart policy;
@@ -147,7 +147,7 @@ published exit events, signals + `process`). On top of those:
to a manager-internal seam.
8. **Discovery migration** — DONE (M19–M20, 2026-07-13): enumeration moved to
ring 3 as swappable per-firmware discoverers — the pci-bus driver (M19) then
the acpi service (M20), see [discovery.md](../os-development-guide/discovery.md); of the enumerable
the acpi service (M20), see [discovery.md](../os-development/discovery.md); of the enumerable
devices, the kernel seeds only the host bridge and the acpi-tables node (the
non-enumerable platform nodes — processors, interrupt controllers, the HPET,
the loader's framebuffer — stay kernel-seeded too). Matching moved with it:
docs/device-driver-development-guide/display-plan.md → docs/device-driver-development/display-plan.md
View File
docs/device-driver-development-guide/display-v2-plan.md → docs/device-driver-development/display-v2-plan.md
View File
docs/device-driver-development-guide/display-v2.md → docs/device-driver-development/display-v2.md
+1 -1
View File
@@ -144,4 +144,4 @@ path in VMs**, where danos development happens. The framebuffer floor never goes
- [display.md](display.md) — v1: the compositor, the GOP-vs-device split, the WC discipline.
- [display-v2-plan.md](display-v2-plan.md) — the ordered build-out.
- [driver-model.md](driver-model.md) — claim / `mmio_map` / MSI / capability passing (M13).
- [resilience.md](../os-development-guide/resilience.md) — the restart machinery the hot-attach leans on.
- [resilience.md](../os-development/resilience.md) — the restart machinery the hot-attach leans on.
docs/device-driver-development-guide/display.md → docs/device-driver-development/display.md
+12 -12
View File
@@ -1,6 +1,6 @@
# The display service: a framebuffer compositor
The [framebuffer](../os-development-guide/framebuffer.md) the loader hands over is a flat block of pixel
The [framebuffer](../os-development/framebuffer.md) the loader hands over is a flat block of pixel
memory, and the kernel's [bootstrap console](../../system/kernel/console.zig) draws text
into it directly. That console is a stop-gap. The **display service**
(`system/services/display/`) is the real thing: an ordinary ring-3 process that *owns*
@@ -22,7 +22,7 @@ which one you're holding decides what you can do.
linear framebuffer pointer and can set video modes — but only until
`ExitBootServices`. The loader already leans on this: [`queryFramebuffer`](../../boot/efi.zig)
reads the monitor's EDID, picks the native mode, and calls `set_mode` **before**
exiting ([gop.md](../os-development-guide/gop.md)). Once the kernel runs, GOP is **gone** — no `set_mode`, no
exiting ([gop.md](../os-development/gop.md)). Once the kernel runs, GOP is **gone** — no `set_mode`, no
mode list, no EDID. What survives is the frozen snapshot in
[`BootInformation.framebuffer`](../../system/boot-handoff.zig): `{base, width, height,
pitch, format, refresh_hz}`, and nothing more.
@@ -66,7 +66,7 @@ rest of the system hasn't had to face:
[`console.zig`](../../system/kernel/console.zig). It is *not* a
[devices-broker](../../system/kernel/devices-broker.zig) node, so
`device.claim`/`mmio_map` cannot reach it, and there is no framebuffer
[syscall](../os-development-guide/syscall.md). A user-space display service needs a **new mechanism just to
[syscall](../os-development/syscall.md). A user-space display service needs a **new mechanism just to
touch the pixels**. (See "The handoff" below — this is built.)
2. **danos had no cross-process shared memory.** At v1 the memory syscalls were `mmap`
@@ -119,7 +119,7 @@ second backend or a second monitor appears; until then it is complexity with no
The framebuffer crosses into user space through the machinery that already exists for
every other device, rather than a bespoke syscall — so it inherits ownership,
release-on-death, and re-claim-on-restart for free (the [resilience](../os-development-guide/resilience.md)
release-on-death, and re-claim-on-restart for free (the [resilience](../os-development/resilience.md)
story: a crashed display service returns the LFB to the kernel, and its restart
re-claims it).
@@ -160,8 +160,8 @@ Two buffers, with deliberately different memory types:
So a frame is: compose every dirty layer into the cacheable back buffer, then **present**
— copy the changed regions back→front in sequential, WC-friendly writes. Two details the
[framebuffer](../os-development-guide/framebuffer.md) note already establishes carry over: step rows by `pitch`,
not `width*4`; and handle both `rgbx` and `bgrx` [pixel formats](../os-development-guide/gop.md).
[framebuffer](../os-development/framebuffer.md) note already establishes carry over: step rows by `pitch`,
not `width*4`; and handle both `rgbx` and `bgrx` [pixel formats](../os-development/gop.md).
## Flicker vs. tearing — what double buffering does and doesn't buy
@@ -234,7 +234,7 @@ client module, as with every other danos service.
The compositor is the single owner of the framebuffer — only the main `service.run` loop
touches the backend and the layer stack. Tracking the mouse without breaking that
ownership is the display's first use of [threads](../os-development-guide/threading.md): the service is built
ownership is the display's first use of [threads](../os-development/threading.md): the service is built
multi-threaded (`addThreadedUserBinary`) and, at startup, spawns a **mouse-listener
thread** beside the compositor loop.
@@ -242,7 +242,7 @@ thread** beside the compositor loop.
(`input.subscribeMouse()`), accumulates the relative `dx`/`dy` motion into an absolute
cursor position clamped to the screen, and hands it to the compositor. It never touches
the compositor — so no lock guards the framebuffer. A parked `next()` leaves its core
free to halt ([halting.md](../os-development-guide/halting.md)).
free to halt ([halting.md](../os-development/halting.md)).
- **The channel.** A single-slot *latest-value* cell (`CursorChannel`) guarded by a
`Thread.Mutex`: the renderer wants where the cursor *is now*, not a replay of
every delta, so a new position overwrites the old. The listener also **pokes** the
@@ -254,13 +254,13 @@ thread** beside the compositor loop.
which is just a top-z compositor layer — with the existing `configure` + `present` path
(it damages the old and new footprints, so only those two rectangles repaint).
Two threading facts shape this (both in [threading.md](../os-development-guide/threading.md)). IPC **handles do
Two threading facts shape this (both in [threading.md](../os-development/threading.md)). IPC **handles do
not cross threads**, so the listener can't reuse the main loop's endpoint handle — it
`ipc.lookup(.display)`s its *own* handle to the same endpoint to poke through. And a
multi-threaded service doing concurrent IPC is why the kernel's endpoint-create / register
/ lookup syscalls now serialize under the big kernel lock. Shared fate applies: a fault in
the listener takes the whole display down, and the supervisor restarts the process
([resilience.md](../os-development-guide/resilience.md)).
([resilience.md](../os-development/resilience.md)).
## What v1 does not do (and why that's fine)
@@ -317,8 +317,8 @@ packing are additionally covered by pure host unit tests under `zig build test`.
## See also
- [framebuffer.md](../os-development-guide/framebuffer.md) — the linear framebuffer, pitch vs. width, `volatile`.
- [gop.md](../os-development-guide/gop.md) — GOP, and why only linear RGBX/BGRX modes are paintable.
- [framebuffer.md](../os-development/framebuffer.md) — the linear framebuffer, pitch vs. width, `volatile`.
- [gop.md](../os-development/gop.md) — GOP, and why only linear RGBX/BGRX modes are paintable.
- [input.md](input.md) — the sibling service; the async `ipc_send` fan-out.
- [driver-model.md](driver-model.md) — claim / `mmio_map`, capability passing, the trust model.
- [device-manager.md](device-manager.md) — matching and supervision (the native backend's route).
docs/device-driver-development-guide/driver-model.md → docs/device-driver-development/driver-model.md
+4 -4
View File
@@ -34,7 +34,7 @@ plain bus driver with no controller — a USB hub — is also a real thing.
danos already has the right central structure. `system/kernel/devices-broker.zig` holds a table of
`DeviceDescriptor`, each with a parent, a class, and a set of resources. Firmware discovery
seeds it ([discovery.md](../os-development-guide/discovery.md)); `device_register` grows it.
seeds it ([discovery.md](../os-development/discovery.md)); `device_register` grows it.
Three invariants make it a capability system rather than a directory:
@@ -199,7 +199,7 @@ class driver, the device manager, or the kernel may share them freely.
`system_spawn(name, arguments)` loads a binary bundled in the initial-ramdisk as a
fresh ring-3 process; `name` becomes the child's argv[0] and the optional
NUL-separated `arguments` blob its argv[1..], delivered on a SysV entry stack
([sysv.md](../os-development-guide/sysv.md)). This is what
([sysv.md](../os-development/sysv.md)). This is what
turned the device manager from "log the match" into "run the driver": the kernel now
spawns only `init`, `init` spawns the services, and the **device-manager** discovers
the hardware and spawns each driver ([drivers.md](drivers.md)). Ungated for now — a
@@ -398,6 +398,6 @@ from hand-rolling `*volatile` and getting ARM wrong.
## See also
- [drivers.md](drivers.md) — how to write one, concretely.
- [discovery.md](../os-development-guide/discovery.md) / [acpi.md](../os-development-guide/acpi.md) — where the device table comes from.
- [discovery.md](../os-development/discovery.md) / [acpi.md](../os-development/acpi.md) — where the device table comes from.
- [ipc.md](ipc.md) — endpoints, badges, and the notification path an IRQ arrives on.
- [resilience.md](../os-development-guide/resilience.md) — restart, the reason any of this is worth the trouble.
- [resilience.md](../os-development/resilience.md) — restart, the reason any of this is worth the trouble.
docs/device-driver-development-guide/drivers.md → docs/device-driver-development/drivers.md
+5 -5
View File
@@ -4,13 +4,13 @@ In a monolithic kernel a driver is a function call away from everything: it runs
ring 0, dereferences any physical address, and its interrupt handler *is* the ISR. In
danos a driver is **an ordinary ring-3 process**. It has its own address space, it
can crash without taking the kernel with it, and — the point of this document — it
can be restarted ([resilience](../os-development-guide/resilience.md)).
can be restarted ([resilience](../os-development/resilience.md)).
That leaves three questions the kernel has to answer, because a process can't answer
them for itself:
1. **What hardware exists?** → `device_enumerate`, over the device table discovery built
([discovery](../os-development-guide/discovery.md), [acpi](../os-development-guide/acpi.md)).
([discovery](../os-development/discovery.md), [acpi](../os-development/acpi.md)).
2. **How do I touch its registers?** → `device_claim` + `mmio_map`: the kernel maps the
device's physical MMIO window into your address space, and from then on it's plain
memory. No syscall per register access.
@@ -51,7 +51,7 @@ the optional arguments its argv[1..], on a SysV entry stack, see sysv.md). Every
is the **driver supervisor**. It does the three steps a monolithic kernel would do in
its probe path, entirely from ring 3:
1. **Discover** — `device_enumerate` snapshots the device table the kernel built from
ACPI/PCI ([discovery](../os-development-guide/discovery.md)).
ACPI/PCI ([discovery](../os-development/discovery.md)).
2. **Match** — for each device it looks up a driver. The match policy is code, a few
small per-bus tables: from the boot snapshot only the PCI host bridge matches
(→ `pci-bus`); everything else arrives later as bus reports and matches on
@@ -293,7 +293,7 @@ the device's `io_port` resource — direct ring-3 `in`/`out` is still a #GP, so
uncacheable, physical address exposed), **memory barriers** (`library/device/mmio`'s
`memoryBarrier`/`readMemoryBarrier`/`writeMemoryBarrier`, imported as the `mmio` module), **fault isolation** (a ring-3 fault kills only the faulting
process — `killCurrentProcess` — and the machine keeps running,
[resilience](../os-development-guide/resilience.md)), and **reclaim + restart on death** (every path out of a
[resilience](../os-development/resilience.md)), and **reclaim + restart on death** (every path out of a
process releases its claims and IRQ/MSI bindings — `releaseAllOwnedBy`,
`irq.releaseOwner` — and the device manager respawns the driver with backoff,
[device-manager.md](device-manager.md)). What remains:
@@ -394,7 +394,7 @@ Claiming and mapping is half of being a danos driver; the other half is the
- Build on `service.run` — one replyWait loop folding protocol
requests, signals, and notifications into callbacks. The harness answers the
universal zero-length ping and turns `terminate` into a clean exit for you
([process-lifecycle.md](../os-development-guide/process-lifecycle.md)).
([process-lifecycle.md](../os-development/process-lifecycle.md)).
- A driver spawned with an assignment (its device id as argv[1]) sends the
versioned `hello` to the device manager inside the deadline, and a **bus**
driver reports what it discovers with `child_added`
docs/device-driver-development-guide/input.md → docs/device-driver-development/input.md
+1 -1
View File
@@ -160,5 +160,5 @@ serial line names the class received, so the log shows all three arriving on one
## See also
- [ipc.md](ipc.md) — the synchronous rendezvous and the notification path `ipc_send` extends.
- [syscall.md](../os-development-guide/syscall.md) — the system-call surface, including `ipc_send`.
- [syscall.md](../os-development/syscall.md) — the system-call surface, including `ipc_send`.
- [driver-model.md](driver-model.md) — class drivers, capability passing (M13), the trust model.
docs/device-driver-development-guide/intel-igpu.md → docs/device-driver-development/intel-igpu.md
View File
docs/device-driver-development-guide/ipc.md → docs/device-driver-development/ipc.md
+3 -3
View File
@@ -18,7 +18,7 @@ There are two layers, built a milestone apart:
The first form is a **bounded blocking channel** (`system/kernel/ipc.zig`): a fixed-size
ring buffer of messages with a producer/consumer rendezvous, built on the
scheduler's [wait queues](../os-development-guide/scheduling.md).
scheduler's [wait queues](../os-development/scheduling.md).
`Channel(T, capacity)` is generic over the message type and buffer size. It holds a
ring buffer, a count, and two wait queues:
@@ -37,7 +37,7 @@ Two details make it correct:
rather than assuming the slot is still available — another waiter may have taken
it first. This is the standard guard against spurious or racing wakeups.
- **One critical section.** `send`/`receive` run under the [big kernel
lock](../os-development-guide/smp.md) (`sync.enter` / `sync.leave`), which disables interrupts on this
lock](../os-development/smp.md) (`sync.enter` / `sync.leave`), which disables interrupts on this
core *and* takes the kernel's one spinlock — since SMP, the interrupt flag alone
is not atomicity, because `cli` on one core does nothing to another. So checking
the condition and committing the block/enqueue happen atomically both with respect
@@ -114,7 +114,7 @@ This is what makes a user-space driver possible at all, and it's the subject of
## Lifecycle conventions over IPC (M17)
Three conventions from [process-lifecycle.md](../os-development-guide/process-lifecycle.md) ride the
Three conventions from [process-lifecycle.md](../os-development/process-lifecycle.md) ride the
notification mechanism:
- **Signals** arrive as notifications on the endpoint a process nominated with
docs/device-driver-development-guide/nvidia-gpus.md → docs/device-driver-development/nvidia-gpus.md
View File
docs/device-driver-development-guide/usb-hub.md → docs/device-driver-development/usb-hub.md
View File
docs/file-system-development/danos-file-system-hierarchy-FSH.md
+2 -2
View File
@@ -49,7 +49,7 @@ addressed by device id. `/dev` is the much smaller set of devices that have a dr
willing to serve them, addressed by name.
A device node is not a file the VFS can read. The bytes live in a driver process
([drivers.md](../device-driver-development-guide/drivers.md)), so opening a `/dev` name has to resolve to that driver's
([drivers.md](../device-driver-development/drivers.md)), so opening a `/dev` name has to resolve to that driver's
IPC endpoint, and subsequent reads and writes are calls against it. Resolve-to-endpoint
is exactly what the kernel's `fs_resolve` already does for any mounted backend, and
`FileStatus.kind` is the field that marks a device node; **what is not implemented today
@@ -92,7 +92,7 @@ descriptor ring and left to read and write memory on its own. That ring is exact
**`dma_alloc`** now provides — physically contiguous, pinned, uncacheable, with its
physical address disclosed — and **`/lib/device/mmio`**'s barriers order the descriptor writes
against the doorbell, and **`msi_bind`** delivers completions. So an AHCI or NVMe driver
can be written today (the M14/M15 work in [driver-model.md](../device-driver-development-guide/driver-model.md); the earlier
can be written today (the M14/M15 work in [driver-model.md](../device-driver-development/driver-model.md); the earlier
"cannot host a block driver at all" is no longer true).
What is *not* yet true is that it is safe. A device programmed with an arbitrary physical
docs/file-system-development/vfs-protocol.md
+1 -1
View File
@@ -9,7 +9,7 @@
> backend, unchanged. The Zig source of truth is `library/protocol/vfs/vfs-protocol.zig`
> (the `vfs-protocol` module), whose unit test pins a sample of the sizes
> and values below. This page is the **language-neutral wire specification**
> of that contract — what a Rust or C client implements ([vdso.md](../os-development-guide/vdso.md)
> of that contract — what a Rust or C client implements ([vdso.md](../os-development/vdso.md)
> explains why the IPC protocols, not the syscall numbers, are danos's
> public ABI).
docs/os-development-guide/README.MD → docs/os-development/README.MD
View File
docs/os-development-guide/acpi.md → docs/os-development/acpi.md
View File
docs/os-development-guide/architecture.md → docs/os-development/architecture.md
+1 -1
View File
@@ -75,7 +75,7 @@ There are really two independent questions, and it's worth not conflating them:
- **`system/kernel/architecture/x86_64/paging.zig`** — the kernel's page tables and address-space
management (see [paging.md](paging.md)).
- **`system/kernel/architecture/x86_64/apic.zig`** / **`ioapic.zig`** — the Local APIC, its timer,
and the I/O APIC for device interrupts (see [device-interrupts.md](../device-driver-development-guide/device-interrupts.md)).
and the I/O APIC for device interrupts (see [device-interrupts.md](../device-driver-development/device-interrupts.md)).
- **`system/kernel/architecture/x86_64/serial.zig`** / **`io.zig`** — the COM1 UART (the kernel's
machine-readable log channel, see [testing.md](../testing.md)) and the shared port-I/O + MSR primitives.
- **`system/kernel/architecture/x86_64/smp.zig`** / **`per-cpu.zig`** — application-processor bring-up
docs/os-development-guide/arm.md → docs/os-development/arm.md
View File
docs/os-development-guide/discovery.md → docs/os-development/discovery.md
+7 -7
View File
@@ -132,7 +132,7 @@ when*:
- **User-space enumeration: a device-manager server.** Everything else — PCI devices,
peripherals — is parsed (or queried from the kernel's parse) by a privileged
user-space server that hands each driver process its MMIO regions and IRQ rights
over [IPC](../device-driver-development-guide/ipc.md). Combined with **interrupts-as-messages** (an IRQ delivered to a
over [IPC](../device-driver-development/ipc.md). Combined with **interrupts-as-messages** (an IRQ delivered to a
driver as a message on a channel — a natural extension of the wait queues and
channels already built), that's what makes drivers genuinely isolated.
@@ -144,7 +144,7 @@ slice is unavoidably in-kernel.
On ARMv8 the generic timer exposes its frequency directly via the `CNTFRQ` register —
no calibration needed. That's cleaner than the x86 side, where we measure the LAPIC
and TSC against the PIT because nothing tells us their frequency (see
[device-interrupts.md](../device-driver-development-guide/device-interrupts.md)). Discovery on ARM hands you more for
[device-interrupts.md](../device-driver-development/device-interrupts.md)). Discovery on ARM hands you more for
free; discovery on x86 is partly about *finding* what ARM just tells you.
## Suggested ordering
@@ -166,9 +166,9 @@ free; discovery on x86 is partly about *finding* what ARM just tells you.
- [arm.md](arm.md) — the aarch64 target that forces genuine discovery (DTB, GIC).
- [memory-map.md](memory-map.md) — the same loader-captures / kernel-consumes seam,
and the note about grabbing the RSDP before `ExitBootServices`.
- [device-interrupts.md](../device-driver-development-guide/device-interrupts.md) — the LAPIC/timer bring-up that
- [device-interrupts.md](../device-driver-development/device-interrupts.md) — the LAPIC/timer bring-up that
discovery will eventually feed (IOAPIC, real IRQ routing).
- [ipc.md](../device-driver-development-guide/ipc.md) — the channels that interrupts-as-messages and the device manager
- [ipc.md](../device-driver-development/ipc.md) — the channels that interrupts-as-messages and the device manager
will ride on.
- [vision.md](../vision.md) — why drivers belong in isolated user space at all.
@@ -177,7 +177,7 @@ free; discovery on x86 is partly about *finding* what ARM just tells you.
The kernel now seeds only the `pci_host_bridge` node (ECAM window, MMIO
apertures derived from the memory map's holes, bus range, and the 16-bit I/O
window). The per-function walk moved to the ring-3 `pci-bus` driver
([device-manager.md](../device-driver-development-guide/device-manager.md)): it claims the bridge, repeats the
([device-manager.md](../device-driver-development/device-manager.md)): it claims the bridge, repeats the
ECAM scan through its mmio grant, and `device_register`s what it finds, which
the device manager mirrors and matches. The ACPI namespace walk follows in M20;
the static tables (MADT, HPET, MCFG, FADT + `\\_S5`) stay kernel-side.
@@ -190,7 +190,7 @@ for the host bridge, FADT); at this point it also still built the AML namespace
but only to read the `\\_S5` sleep type for poweroff. (That remnant is gone too:
the kernel now runs no AML at all — soft-off belongs to the acpi service, and the
kernel keeps only the AML-free reboot path.) Device discovery is the ring-3 **acpi
service** ([device-manager.md](../device-driver-development-guide/device-manager.md)): it claims the `acpi-tables`
service** ([device-manager.md](../device-driver-development/device-manager.md)): it claims the `acpi-tables`
node the kernel publishes (the AML blobs, a broad io_port grant, the SCI),
re-parses the same blobs with the shared AML module, evaluates `_STA`/`_CRS`,
and registers + reports each `_HID` device — the device manager matches drivers
@@ -206,7 +206,7 @@ ring 0.)
Moving PCI and ACPI enumeration out of ring 0 was not just a relocation — it
made discovery **firmware-neutral by construction**, which is the whole reason
to do it before the second architecture rather than after. Everything at and
above the [device-manager](../device-driver-development-guide/device-manager.md) protocol — descriptors,
above the [device-manager](../device-driver-development/device-manager.md) protocol — descriptors,
containment, reports, matching, supervision — is generic and may never become
x86-specific. Discovery is the single firmware-specific piece, and it is
isolated as **one swappable process per firmware**:
docs/os-development-guide/efi.md → docs/os-development/efi.md
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docs/os-development-guide/frame-allocator.md → docs/os-development/frame-allocator.md
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docs/os-development-guide/framebuffer.md → docs/os-development/framebuffer.md
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docs/os-development-guide/gop.md → docs/os-development/gop.md
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docs/os-development-guide/halting.md → docs/os-development/halting.md
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docs/os-development-guide/heap.md → docs/os-development/heap.md
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docs/os-development-guide/interrupts.md → docs/os-development/interrupts.md
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@@ -136,7 +136,7 @@ Both items originally deferred here have landed:
- **The IO-APIC**: [ioapic.zig](../../system/kernel/architecture/x86_64/ioapic.zig)
routes external device lines onto vectors — discovered via ACPI's MADT, every
input masked at init, lines unmasked one at a time as user-space drivers bind
them (see [device-interrupts.md](../device-driver-development-guide/device-interrupts.md)). The keyboard followed
them (see [device-interrupts.md](../device-driver-development/device-interrupts.md)). The keyboard followed
exactly as predicted: the PS/2 bus driver (`system/drivers/ps2-bus/`) claims
the 8042 controller and binds its IRQ 1 (and the aux mouse's IRQ 12) through
this routing. USB HID keyboards arrive over xHCI instead, which interrupts via
docs/os-development-guide/logging.md → docs/os-development/logging.md
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docs/os-development-guide/memory-map.md → docs/os-development/memory-map.md
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docs/os-development-guide/paging.md → docs/os-development/paging.md
+2 -2
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@@ -138,8 +138,8 @@ Four tests (see [testing.md](../testing.md)) pin down the guarantees:
processes own the low half.
- **Per-address-space tables** — done: each user process gets its own root with
the kernel half shared, and refcounted shared-memory mappings exist
([ipc.md](../device-driver-development-guide/ipc.md)). Copy-on-write remains unbuilt — nothing has needed it yet.
([ipc.md](../device-driver-development/ipc.md)). Copy-on-write remains unbuilt — nothing has needed it yet.
- **Uncacheable MMIO** — half done: user-space device and DMA mappings are
strong-uncacheable and the framebuffer is write-combining via the PAT, but the
kernel's own `mapMmio` path is still writeback — the LAPIC included (see
[device-interrupts.md](../device-driver-development-guide/device-interrupts.md)).
[device-interrupts.md](../device-driver-development/device-interrupts.md)).
docs/os-development-guide/power.md → docs/os-development/power.md
+2 -2
View File
@@ -7,7 +7,7 @@ them owns the hardware that reported the event, and the reporter should not know
who is listening. So system power is a **service**: an event source **publishes**
button/lid/battery/AC events, interested processes **subscribe**, and one
privileged caller — init — can ask it to power the machine off. It is the same
publish/subscribe shape as the [input service](../device-driver-development-guide/input.md), applied to power.
publish/subscribe shape as the [input service](../device-driver-development/input.md), applied to power.
## Why a service, and why it is named for the domain, not the firmware
@@ -126,5 +126,5 @@ until laptop sleep), and thermal zones.
firmware neutrality that makes a PSCI backend drop-in on ARM.
- [process-lifecycle.md](process-lifecycle.md) — the stop sequence
(`terminate → deadline → kill`) and signals init composes into shutdown.
- [device-manager.md](../device-driver-development-guide/device-manager.md) — the supervision model init mirrors for
- [device-manager.md](../device-driver-development/device-manager.md) — the supervision model init mirrors for
its own children.
docs/os-development-guide/process-lifecycle.md → docs/os-development/process-lifecycle.md
+3 -3
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@@ -9,7 +9,7 @@ the layer above them — the standard vocabulary a danos process speaks about it
life, and the stable `process` interface that carries it. Nothing here is
device- or driver-specific: a driver, the VFS, and a user application all stop,
reload, and die the same way. The device manager is simply this design's first
serious customer ([device-manager.md](../device-driver-development-guide/device-manager.md)).
serious customer ([device-manager.md](../device-driver-development/device-manager.md)).
**"POSIX" in this document means the concepts, never the letter of the standard.**
danos borrows the ideas and the hard-won lessons (what SIGTERM *means*, why SIGPIPE
@@ -172,7 +172,7 @@ zombie state or privileged snooping:
the server's reply with `-EPEER`; a server that dies fails its waiting clients
the same way. This covers the *synchronous* case only.
3. **The subscribers** — the new piece, and it is the input service's
publish/subscribe shape ([input.md](../device-driver-development-guide/input.md)) applied to exits. A stateful
publish/subscribe shape ([input.md](../device-driver-development/input.md)) applied to exits. A stateful
service accumulates per-client state across many requests: a filesystem server
(FAT today) holds a dead client's open file handles, the input service holds
its subscriptions, a future network stack holds its sockets. None of these
@@ -320,7 +320,7 @@ get POSIX; danos-native programs never pay for it.
`process` grows the interface above; the service harness handles
`terminate` and answers the common `ping`; `stop()` for supervisors.
[device-manager.md](../device-driver-development-guide/device-manager.md) builds directly on all four.
[device-manager.md](../device-driver-development/device-manager.md) builds directly on all four.
## Settled questions (2026-07-12)
docs/os-development-guide/process-management.md → docs/os-development/process-management.md
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docs/os-development-guide/release-iso.md → docs/os-development/release-iso.md
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docs/os-development-guide/resilience.md → docs/os-development/resilience.md
+3 -3
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@@ -5,7 +5,7 @@ isolation; fault → kill the process → keep the core (`onException`; the
`fault-recovery` test); the supervisor notification **with exit reasons**
([process-lifecycle.md](process-lifecycle.md) — clean exit, fault class, or
killed, recorded before the notice posts); and the **restart policy itself**
([device-manager.md](../device-driver-development-guide/device-manager.md)): the device manager supervises every
([device-manager.md](../device-driver-development/device-manager.md)): the device manager supervises every
driver, restarts crashes with backoff, caps crash loops, and re-claims work
because the kernel releases a dead process's claims. The `driver-restart` and
`usb-report` scenarios prove kill → release → respawn → re-claim → re-report
@@ -81,7 +81,7 @@ Detecting and killing is the easy half. The genuinely tricky questions are about
- **In-flight IPC**: messages sent to the dead component, or replies its clients are
blocked waiting for. The channel has to break cleanly and unblock the waiters with
an error rather than hang them forever (a design constraint that reaches back into
[ipc.md](../device-driver-development-guide/ipc.md) — channels need a "peer died" outcome).
[ipc.md](../device-driver-development/ipc.md) — channels need a "peer died" outcome).
- **Clients**: how does a client discover the service it was talking to is gone and
has been replaced? Options: capability revocation makes stale handles fail; or a
**name server** re-binds clients to the new instance; or clients retry through a
@@ -159,7 +159,7 @@ real-time work without owing anyone a timing *guarantee*.
- [vision.md](../vision.md) — the goals this serves (learning by doing; resilience over
hard real-time).
- [scheduling.md](scheduling.md) — preemption, which makes runaway components killable.
- [ipc.md](../device-driver-development-guide/ipc.md) — channels that need a "peer died" outcome for clean restart.
- [ipc.md](../device-driver-development/ipc.md) — channels that need a "peer died" outcome for clean restart.
- [interrupts.md](interrupts.md) — fault reporting that user mode turns into "kill and
restart" instead of "halt".
- [smp.md](smp.md) — the real-time-vs-resilience fork, in the SMP context.
docs/os-development-guide/scheduling.md → docs/os-development/scheduling.md
+3 -3
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@@ -37,7 +37,7 @@ down a return address pointing at `task_trampoline` and zeroed callee-saved slot
`schedule()` — pick the best task and switch — runs from two places:
- **`yield()`** — a task voluntarily gives up the CPU.
- **`tick()`** — the 1000 Hz [timer](../device-driver-development-guide/device-interrupts.md) preempts the running
- **`tick()`** — the 1000 Hz [timer](../device-driver-development/device-interrupts.md) preempts the running
task. This is what lets a task that never yields still share the CPU.
The subtlety in mixing them is the **interrupt flag (IF)**. The rule: `switch_context`
@@ -97,7 +97,7 @@ marks the task blocked with a wake deadline and switches away. On every tick the
timer wakes any task whose deadline has passed (a bounded scan, so it stays
deterministic), which makes it ready again; the scheduler then runs it when its
priority comes up. `sleep` measures its deadline on the [calibrated
clock](../device-driver-development-guide/device-interrupts.md), so it's real time.
clock](../device-driver-development/device-interrupts.md), so it's real time.
When *every* task is blocked, something still has to run — so there's an **idle
task** at the lowest priority that just `hlt`s until the next interrupt (see
@@ -111,7 +111,7 @@ The other form of blocking is waiting for an **event** rather than a duration. A
the caller on it, `wake(wq)` moves the highest-priority waiter back to ready
(preempting if it now outranks the running task). A task links into a wait queue
through the same field the ready queues use — it's in exactly one queue at a time.
These are the primitives locks, semaphores and [IPC](../device-driver-development-guide/ipc.md) are built on.
These are the primitives locks, semaphores and [IPC](../device-driver-development/ipc.md) are built on.
Blocking safely needs **composable critical sections**. A blanket `cli`/`sti` pair
doesn't nest: an IPC channel that `cli`s and then calls `wait` would have `wait`'s
docs/os-development-guide/shared-fate-plan.md → docs/os-development/shared-fate-plan.md
+1 -1
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@@ -307,4 +307,4 @@ refcount, and no group-kill special case is needed at all.
Then update [threading.md](threading.md) (the shared-fate gap note),
[process-lifecycle.md](process-lifecycle.md),
[process-management.md](process-management.md), and
[ipc.md](../device-driver-development-guide/ipc.md)/[drivers.md](../device-driver-development-guide/drivers.md) mentions.
[ipc.md](../device-driver-development/ipc.md)/[drivers.md](../device-driver-development/drivers.md) mentions.
docs/os-development-guide/smp.md → docs/os-development/smp.md
+1 -1
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@@ -270,6 +270,6 @@ next lands.
- [scheduling.md](scheduling.md) — the single-core scheduler SMP would extend.
- [discovery.md](discovery.md) — enumerating cores is a device-discovery problem.
- [ipc.md](../device-driver-development-guide/ipc.md) — the message passing cross-core coordination rides on.
- [ipc.md](../device-driver-development/ipc.md) — the message passing cross-core coordination rides on.
- [vision.md](../vision.md) — the goals question (real-time vs resilience) this note
keeps bumping into.
docs/os-development-guide/syscall.md → docs/os-development/syscall.md
+1 -1
View File
@@ -51,7 +51,7 @@ Everything else---including`read()`,`write()`,`malloc()`, and`fork()`---will run
3. **`Yield()`/`Thread_Ctrl()`**
- **What it does:**Allows a thread to voluntarily give up its CPU time slice, or allows a root task to spawn/kill threads.
4. **`ipc_send(endpoint, message_buffer)`(Asynchronous Send)**
- **What it does:**Posts a small payload to an endpoint's bounded queue and returns *without* blocking — no rendezvous, no reply. The receiver picks it up through the same `IPC_ReplyWait`, as a buffered message. It is the async counterpart of `IPC_Call`, for one-to-many broadcasts where a synchronous rendezvous would let one dead or slow receiver hang the sender. The [input service](../device-driver-development-guide/input.md) — keyboard-event fan-out — is its first user. A full queue drops the oldest message (a buffered message is discrete data, unlike a coalescing interrupt notification).
- **What it does:**Posts a small payload to an endpoint's bounded queue and returns *without* blocking — no rendezvous, no reply. The receiver picks it up through the same `IPC_ReplyWait`, as a buffered message. It is the async counterpart of `IPC_Call`, for one-to-many broadcasts where a synchronous rendezvous would let one dead or slow receiver hang the sender. The [input service](../device-driver-development/input.md) — keyboard-event fan-out — is its first user. A full queue drops the oldest message (a buffered message is discrete data, unlike a coalescing interrupt notification).
* * * * *
docs/os-development-guide/system-image.md → docs/os-development/system-image.md
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docs/os-development-guide/sysv.md → docs/os-development/sysv.md
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docs/os-development-guide/threading-plan.md → docs/os-development/threading-plan.md
+2 -2
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@@ -2,7 +2,7 @@
The ordered, checkpointable build-out for [threading.md](threading.md). Each milestone
lands on its own and ends in a **verifiable gate** — shaped for a `/loop` run, like
[display-v2-plan.md](../device-driver-development-guide/display-v2-plan.md). Read threading.md first for the *why*.
[display-v2-plan.md](../device-driver-development/display-v2-plan.md). Read threading.md first for the *why*.
## Locked decisions (do not relitigate)
@@ -459,7 +459,7 @@ clean.
## Deferred (explicitly not in this plan)
- **Cross-process shared-memory futex** — the `(address_space, virtual_address)` key can become a
physical-address key so two processes share a futex through a [shared-memory](../device-driver-development-guide/display-v2.md)
physical-address key so two processes share a futex through a [shared-memory](../device-driver-development/display-v2.md)
region. Not needed for intra-process threads.
- **Per-thread priorities / affinity distinct from the process** — threads inherit the
process priority ([scheduling.md](scheduling.md)); revisit only if it earns its keep.
docs/os-development-guide/threading.md → docs/os-development/threading.md
+5 -5
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@@ -36,7 +36,7 @@ implementation underneath, not the API above.
[Why not literal std.Thread](#why-not-literal-stdthread).
- **Threads are a narrow, opt-in capability — not the default concurrency tool.** The
default for resilience stays **process + IPC** ([resilience.md](resilience.md),
[ipc.md](../device-driver-development-guide/ipc.md)). See [Where threads fit](#where-threads-fit-the-resilience-tension).
[ipc.md](../device-driver-development/ipc.md)). See [Where threads fit](#where-threads-fit-the-resilience-tension).
- **Blocking synchronization is futex-backed, never spin-backed.** Waiters sleep in
the kernel so an idle core still halts ([halting.md](halting.md)).
- **Per-binary opt-in to multi-threaded codegen.** Only a service that asks for
@@ -214,7 +214,7 @@ Keying: threads share an address space, so a **virtual address within that addre
identifies a futex uniquely; the kernel keys its wait queue by `(address_space_root, virtual_address)`.
Keying by the **physical** address instead (translate `virtual_address -> physical_address` on entry) is a
deliberate forward door: it lets two *processes* share a futex through an
[shared-memory](../device-driver-development-guide/display-v2.md) region later, without changing the API. We start with the
[shared-memory](../device-driver-development/display-v2.md) region later, without changing the API. We start with the
private-per-address-space key and note the physical-key upgrade.
No spinning: a contended lock parks the task in the kernel and the core is free to run
@@ -264,7 +264,7 @@ stays single-threaded and lean.
**process**, which respawns its threads from a known-good state — restart
granularity stays the process. The leader's recorded exit reason carries the fault
class even when a worker faulted, so restart policy is unchanged.
- **IPC — two consequences threads forced ([ipc.md](../device-driver-development-guide/ipc.md)):**
- **IPC — two consequences threads forced ([ipc.md](../device-driver-development/ipc.md)):**
- *Handles do not cross threads.* The handle table lives on the `Task`
([scheduler.zig](../../system/kernel/scheduler.zig)), so a handle number is meaningful
only to the thread that created it — thread A's endpoint handle `3` is not thread B's.
@@ -284,7 +284,7 @@ stays single-threaded and lean.
The ordered, `/loop`-runnable milestones live in
**[threading-plan.md](threading-plan.md)** (shaped like
[display-v2-plan.md](../device-driver-development-guide/display-v2-plan.md)): every milestone lands on its own and ends in
[display-v2-plan.md](../device-driver-development/display-v2-plan.md)): every milestone lands on its own and ends in
a verifiable gate (`python3 test/qemu_test.py <case>`, asserting serial markers;
`zig build test` for host unit tests). The stages below are the shape it expands.
@@ -343,7 +343,7 @@ the later self-hosting lift cheap.
- [scheduling.md](scheduling.md), [smp.md](smp.md) — the task model these threads join.
- [resilience.md](resilience.md), [vision.md](../vision.md) — why isolation is the default
and threads are the exception.
- [syscall.md](syscall.md), [ipc.md](../device-driver-development-guide/ipc.md) — the private ABI and the messaging model
- [syscall.md](syscall.md), [ipc.md](../device-driver-development/ipc.md) — the private ABI and the messaging model
threads sit beside.
- [halting.md](halting.md) — the idle/halt property futex-backed blocking preserves.
- [zig-self-hosting.md](../zig-self-hosting.md) — the target this bends toward.
docs/os-development-guide/timers.md → docs/os-development/timers.md
+4 -4
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@@ -7,7 +7,7 @@ Two different needs hide under the word "timer", and danos keeps them apart:
Both are answered by the **kernel**, because the kernel already owns a timer: it has
to, to preempt tasks. The LAPIC heartbeat and the calibrated TSC that back all of this
are built in [device-interrupts.md](../device-driver-development-guide/device-interrupts.md); the scheduler's blocking and
are built in [device-interrupts.md](../device-driver-development/device-interrupts.md); the scheduler's blocking and
wait queues are in [scheduling.md](scheduling.md). This page is about the surface a
ring-3 program actually uses, and one deliberate absence: **there is no user-space time
service.**
@@ -32,11 +32,11 @@ danos checks both — the invariant-TSC CPUID bit (`0x80000007` EDX[8], set on I
AMD), and a cross-core "warp" check as the cores come up — and falls back to the HPET
counter when either fails. So `now()` stays accurate on a real Intel box, a real AMD box,
and inside a VM alike; only the source behind it differs. The mechanism is in
[device-interrupts.md](../device-driver-development-guide/device-interrupts.md).
[device-interrupts.md](../device-driver-development/device-interrupts.md).
So the timer hardware lives in the kernel, and there is **no `hpet` driver and no time
server** to consume. (An earlier HPET driver existed only to *demonstrate* the driver
model; that role now lives in [drivers.md](../device-driver-development-guide/drivers.md), as documentation.) The one place
model; that role now lives in [drivers.md](../device-driver-development/drivers.md), as documentation.) The one place
a user-space time service *is* justified — **wall-clock / calendar time** — is discussed
at the end; it is deliberately not built yet.
@@ -55,7 +55,7 @@ Time and waiting are three entries in the small syscall table ([syscall.md](sysc
service can keep answering messages on the same endpoint while a deadline is pending.
This is the timed wait that stop-sequence escalation, hello deadlines, and restart
backoff are built from ([process-lifecycle.md](process-lifecycle.md),
[device-manager.md](../device-driver-development-guide/device-manager.md)).
[device-manager.md](../device-driver-development/device-manager.md)).
The kernel's own scheduling timer (the LAPIC, vector 32) is never exposed to user space;
programs read the TSC through `clock` and get timed wakeups through `sleep`/`timer_bind`,
docs/os-development-guide/vdso.md → docs/os-development/vdso.md
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docs/system-requirements.md
+1 -1
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@@ -118,7 +118,7 @@ hypervisor configured for UEFI firmware and an xHCI USB controller.
(`system/kernel/acpi.zig:3`)
- The loader reads `/system/kernel` off the FAT boot volume, then loads user
space: a prebuilt `boot\system.img` capsule
([system-image.md](os-development-guide/system-image.md)) when present, otherwise it walks
([system-image.md](os-development/system-image.md)) when present, otherwise it walks
the volume's `/system` and optional `/test` trees (init included) into the
initial ramdisk. The kernel can boot "kernel-only" without either.
(`efi.zig:16`, `efi.zig:68`)
docs/testing.md
+2 -2
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@@ -27,7 +27,7 @@ boot log, memory summary, exception reports — appears on serial as plain text.
QEMU captures that with `-serial file:serial.log`, giving a machine-readable
transcript. Serial is per-architecture (x86 uses port I/O; an ARM board uses a
memory-mapped UART), so it lives behind the [architecture](os-development-guide/architecture.md) boundary — and adding
memory-mapped UART), so it lives behind the [architecture](os-development/architecture.md) boundary — and adding
a new architecture's UART is what makes the same tests run there.
The serial log sink is **compiled in only under `-Dserial`** (off by default).
@@ -88,7 +88,7 @@ table in `test/qemu_test.py`):
| `fault-recovery` | a ring-3 process that faults is killed and reaped while init keeps heartbeating — the OS survives | `DANOS-TEST-RESULT: PASS` |
The faulting cases don't print a result line — they deliberately raise a CPU
exception, and the harness asserts on the [exception report](os-development-guide/interrupts.md) the
exception, and the harness asserts on the [exception report](os-development/interrupts.md) the
handler prints (which also reaches serial). This reuses the real fault path as the
test oracle: if the IDT/TSS weren't wired up, `fault-df` would triple-fault and the
marker would never appear.
docs/zig-self-hosting.md
+6 -6
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@@ -108,7 +108,7 @@ localised (below).
## The architecture decision: `runtime.os` + `runtime.fs`, and retire `posix`
danos already has the right split ([the private-ABI boundary](../README.md)): the
kernel exposes a minimal syscall ABI ([syscall.md](os-development-guide/syscall.md)); the **`runtime`**
kernel exposes a minimal syscall ABI ([syscall.md](os-development/syscall.md)); the **`runtime`**
library is the stable, danos-native application ABI. What this roadmap adds:
- **`runtime.os` — the seam.** A C-ABI-shaped module of the ~30 operations
@@ -165,7 +165,7 @@ What the seam needs, and what danos already provides:
| mmap / munmap | native syscalls ([abi.zig](../system/abi.zig)) | none |
| page allocator | over `mmap`, via `root.os.heap.page_allocator` override | ~30-line hook |
| monotonic clock | `clock` syscall | none |
| args / argv | SysV entry stack ([sysv.md](os-development-guide/sysv.md)), `runtime.process.Init` | none |
| args / argv | SysV entry stack ([sysv.md](os-development/sysv.md)), `runtime.process.Init` | none |
| stdout / stderr | `debug_write` today | wire fd 1/2 to a console **byte** stream |
| mkdir / unlink / rename / truncate | done — engine + VFS + `runtime.fs` (Phase 2) | — |
| stat fields | `{size, kind, mtime}` | **mode / inode** still missing (cache validity) |
@@ -209,7 +209,7 @@ build); point danos's `build.zig`/CI at the resulting binary. Four localised pat
plan9/serenity;
- add `danos` to the freestanding/other **no-op `_start` list** in `std`'s `start.zig`,
so std does *not* emit its own System-V `_start` — danos keeps owning the entry shim
and `Init`/argv construction it already builds ([sysv.md](os-development-guide/sysv.md));
and `Init`/argv construction it already builds ([sysv.md](os-development/sysv.md));
- wire the `system` selector `.danos => std.os.danos` in `std.posix`;
- add `std/os/danos.zig` — **the seam itself**, promoted near-verbatim from the
`runtime.os` developed first in Phase 1 (against the stock toolchain, so the fork is
@@ -344,9 +344,9 @@ Two current decisions fall out of this roadmap:
## Related
- [vision.md](vision.md) — the north star this serves.
- [syscall.md](os-development-guide/syscall.md) — the kernel↔runtime ABI `runtime.os` is built on.
- [sysv.md](os-development-guide/sysv.md) — the entry stack (`argc/argv/envp/auxv`) danos already constructs.
- [ipc.md](device-driver-development-guide/ipc.md) — the IPC the VFS/FAT operations travel over.
- [syscall.md](os-development/syscall.md) — the kernel↔runtime ABI `runtime.os` is built on.
- [sysv.md](os-development/sysv.md) — the entry stack (`argc/argv/envp/auxv`) danos already constructs.
- [ipc.md](device-driver-development/ipc.md) — the IPC the VFS/FAT operations travel over.
- [danos-file-system-hierarchy-FSH.md](file-system-development/danos-file-system-hierarchy-FSH.md) — the
filesystem layout the file surface serves.
- [coding-standards.md](coding-standards.md) — danos naming (why the compat spellings
library/xkeyboard-config/README.md
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# xkeyboard-config — X11 keyboard layouts, compiled to Zig
This module turns a physical key (a **USB HID usage**, as the [input module](../../docs/device-driver-development-guide/input.md)
This module turns a physical key (a **USB HID usage**, as the [input module](../../docs/device-driver-development/input.md)
delivers in `KeyEvent.keycode`) plus a modifier state into a **keysym** and, when the key
produces one, a **character** (a Unicode scalar). It is what lets a `keycode` become a
`character` — a keymap — without danos shipping an X11 runtime.