The payoff milestone: files are served by a user-space process, reached over
IPC — the kernel never sees a path or an fd.
- lib/vfs_proto.zig: the VFS wire protocol (Op, Request/Reply fixed header +
inline payload, Stat), shared by client and server; one message <= MSG_MAX.
- lib/ipc.zig: replyWait() — the server-side dual-return stub (length in rax,
badge in rdx via a "+{rdx}" read-write operand), deferred from M7.
- sbin/vfs.zig: the real VFS server — an in-heap ramfs (open creates a node)
with an IPC_ReplyWait dispatch loop serving open/read/write/stat/close.
Registers its endpoint under the well-known vfs id at startup.
- lib/unistd.zig: POSIX-style client API in rt — a per-process fd table +
open/close/read/write/lseek/stat, each an IPC_Call to the VFS. The kernel
knows nothing of fds; the table lives here.
- lib/stdio.zig: C stdio over unistd — FILE + fopen/fclose/fread/fwrite/
fseek/ftell/rewind/feof/ferror/fputs/fputc/fgetc (unbuffered for now).
- sbin/vfstest.zig: a client that opens/writes/seeks/reads a file and only
heartbeats "vfstest: ok" if the round trip matched. Packed in the initrd.
- New `vfs` test drives it end to end. initrd test relaxed to generic
liveness. Suite 31/31.
Ship more than one user binary: the bootloader now ferries an initrd bundle
(the VFS server + future drivers) alongside sbin/init, and the kernel unpacks
and spawns each program.
- src/user/proto/initrd.zig: the container format (Header{magic,count} +
Entry{name[32],offset,len} + blobs) with a validating Reader, shared by the
kernel and the packer.
- tools/mkinitrd.py: host-side packer (Python — trivial format, and sidesteps
the reworked Zig 0.16 std fs/args API). build.zig runs it on the built user
binaries via addSystemCommand and installs initrd.img to zig-out/bin + the
ESP root.
- BootInfo gains initrd_base/initrd_len; efi.zig loadInit refactored into a
shared loadFile, and loadInitrd ferries \initrd.img into surviving
LoaderData like init.
- main.zig startInitrdBinaries(): parse the image, spawn every entry (kernel-
spawns-all for now; init takes over via sys_spawn later).
- sbin/vfs.zig: a heartbeat stub (the real VFS server is M9), packed into the
initrd to prove the pipeline.
- New `initrd` test: parse + spawn + confirm the vfs stub reaches ring 3 and
heartbeats. Harness ships initrd.img on the ESP. Suite 30/30.
The microkernel message backbone the VFS server and drivers will ride on.
- src/kernel/ipc_sync.zig: Endpoint (sender FIFO threaded via Task.next +
a recv WaitQueue for servers + a small notification ring). call() (client
sends, wakes a server, blocks) and replyWait() (server replies to the held
caller, then receives the next). Reply routing keys on Task.ipc_client —
synchronous IPC owes one reply at a time. Payloads copy frame-to-frame
through the physmap (copyAcross on arch.translate, added in M5); an unmapped
page fails the copy instead of #PF-ing. MSG_MAX 256.
- Bootstrap naming: an integer name registry (danos.ServiceId, vfs=1) with
create_endpoint / ipc_register / ipc_lookup — any process finds a server
without threading a handle through spawn.
- notifyFromIsr(): ISR-safe async wake (badge with the high bit set), the
hook M10's IRQ-as-message needs. Unused/untested until then.
- Task gains handles[16] (opaque *Endpoint, to avoid a sched<->ipc import
cycle) + ipc_client/send/reply/status fields; sched gains
blockCurrentLocked/readyLocked; arch gains setSyscallResult2 (rdx badge).
- Syscalls 6..10 wired in process.zig; exit() now drops the caller's endpoint
refs. lib/ipc.zig: user-side createEndpoint/register/lookup/call
(server-side replyWait lands with the first server in M9).
- New `ipc-call` test: two kernel tasks ping-pong 100 calls, every reply
request+1. Suite 29/29.
Start the user-space driver track (VFS + IPC + heap). This lays the
process/syscall foundation the runtime heap will grow on.
- Rename usermode.zig -> process.zig; drop the retired hello/ping blob and
its `user` test (subsumed by the real /sbin/init exerciser). Keep the
isolation-proof pf blob and the user-pf test.
- Add danos.Syscall as the single source of truth for syscall numbers, shared
by the kernel dispatcher and (later) the user runtime lib. Dispatch on the
enum. New calls: 1=yield, 4=mmap, 5=munmap. Widen debug_write's bounds
check to the whole user low half so heap buffers are writable.
- mmap grants zeroed RW+NX pages from a per-process bump arena
(Task.heap_next, PML4[224] above image+stack); munmap frees the frames.
Add paging.translateIn / unmapInto (+ arch.translate / unmapUserPageInto)
as the primitives munmap and future cross-AS copies need.
- New `usermem` test: grant three pages into a fresh AS, translate them,
release via the munmap path, tear down, and assert no frames leak.
Suite 28/28 (user -> usermem).
The generic kernel imports cpu.zig as @import("arch") but still spoke
x86: readCr3/readCr2, pml4 and rip/rsp parameters, lapicHz/tscHz,
ioapicEntry*, IST stacks, APIC ids. Rename the public interface so the
same names work for x86_64, aarch64, and riscv64:
- readCr3 -> activePageTable; pml4 params -> root; vectorName ->
exceptionName; postCode -> checkpoint; lapicHz/tscHz ->
timerClockHz/clockHz; ioapicEntry* -> irqRoute*; ist_stack_size/
setApIstStack -> fault_stack_size/setFaultStack; startSecondary
takes a hw_id (APIC id here; MPIDR/hart id elsewhere)
- New trap-frame accessors (instructionPointer, stackPointer,
fromUser, faultAddress, syscallNumber/syscallArg/setSyscallResult)
so the generic syscall dispatcher and fault printer never name an
x86 register; readCr2 folds into faultAddress (null unless #PF)
- Generic-kernel identifiers follow: Task.pml4 -> aspace, rsp -> sp,
user_rip/user_rsp -> user_ip/user_sp, PerCpu.apic_id -> hw_id
PlatformConfig fields and the ACPI apic_id stay as-is: they describe
hardware actually discovered on this platform, and another arch would
define its own. The user-mode tests now assert fromUser instead of
the exact CS selector; the user-pf expectation follows the fault
printer's RIP -> IP label. All 28 QEMU tests pass.
Per-process address spaces (AddressSpace = a PML4 with an empty user
half and the shared kernel half copied in; create/destroy in paging.zig)
with CR3 switched on context switch and TSS.rsp0/kernel_rsp published per
switch. The GS base now points at an arch per-CPU block and every ring
transition observes the swapgs discipline, so a ring-3 `mov %ax,%gs` can
no longer poison per-CPU access. syscall/sysret is the primary user entry
(int 0x80 kept as a test path); one handler, installed once at boot,
serves both and dispatches on whether the caller is a scheduled process
or a borrowed test thread. spawnProcess loads an ELF into a fresh address
space and schedules it; exit frees the address space after switching to
the kernel tables. New `process` test: init runs twice as a real process
(create/exit/recreate) on its own page tables, coexisting with a kernel
task under preemption. Suite 28/28.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Ring 3 works: user GDT descriptors (sysret-ready layout), TSS.rsp0,
U/S-bit user mappings (W^X preserved), an int 0x80 syscall gate with a
mutable trap frame, and a setjmp-style enter/exit path. /sbin/init is a
real freestanding Zig binary built from sbin/, shipped on the ESP,
loaded by the bootloader (BootInfo.init_base/len), validated and mapped
by an in-kernel user-ELF loader, and run at CPL 3 — syscalls: exit,
ping, write. Tests: user, user-pf (U/S isolation proof, error code
0x5), init. Suite 27/27.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
fault-ap-df pins a #DF to an AP (its own IST must catch it); affinity checks a pinned task never migrates. onException now names the core, so an AP fault is attributed and shown contained. Both teeth-checked.
Add a discovery case (asserts stable ACPI/MADT/FADT/AML facts) and a wx case (audits R+X code vs NX data/rodata/heap/stack via arch.pageExecutable). Wire the existing poweroff/reboot cases into the harness. Suite: 18 -> 22.
Daniel Samson
Daniel Samson