Add lib/ — the shared user-space runtime every user binary links against
(init now, servers/drivers later): syscall wrappers, the heap, IPC stub,
and the process start shim.
- lib/heap.zig: the kernel first-fit free-list ported to user space, grown
via the mmap syscall instead of pmm+mapPage. Dual API over one global free
list: extern "C" malloc/free/calloc/realloc (C ABI for future C code) and a
std.mem.Allocator adapter (with in-place resize) for Zig std containers.
- lib/syscall.zig + sys.zig: raw syscall0..5 (arg3 in r10) and typed
yield/write/sleep/exit/mmap/munmap over danos.Syscall.
- lib/start.zig: naked _start -> rt_start -> root.main() (SysV realign via
call), panic -> exit(127).
- lib/user.ld: the user link script, moved from sbin/linker.ld (shared by all
user binaries).
- build.zig: register the `rt` module; add an addUserBinary() helper that is
the one recipe for every user binary (freestanding, .large, use_lld,
user.ld, image_base), replacing the bespoke init block.
- sbin/init.zig: migrated onto rt; drops its hand-rolled syscall2/shims. Now
proves the heap (alloc -> write from a heap pointer -> free) before the
heartbeat loop. Serial shows "init: heap ok". Suite 28/28.
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).
init is now a real scheduled ring-3 process: it prints a heartbeat and
sleeps, forever. The kernel spawns it at boot via spawnProcess (its own
address space, preemption on) and the boot context drops to idle — the
system's steady state is "kernel idle, init alive in ring 3", beating
~1 Hz. Adds the sleep(ms) syscall. The init/process tests are reshaped
around the heartbeat (repeated syscalls, still-alive, two concurrent
processes on distinct address spaces). Pins init to LLD and folds the
.large code model's .ltext/.lrodata/.ldata into the linker script so its
code segment is R+X. Removes the now-dead borrowed-thread ELF loader
(runInitElf); spawnProcess is the one path. Docs updated. Suite 28/28.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The kernel now links at 0xFFFF_FFFF_8000_0000 (code_model .kernel) and
loads low via the linker script's AT() clauses (.text at 1 MiB). A new
asm _start installs a 64 KiB kernel-owned .bss stack — the loader stack
is a low address that goes away with the identity map — and calls the
Zig entry, which reaches boot_info through the physmap. The user-pf test
blob reads the LAPIC through the physmap window (still present|user, ec
0x5). The low identity map still coexists in the kernel's tables as the
safety net. Suite 27/27.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The self-hosted linker ignores parts of linker.ld (PHDRS, /DISCARD/,
section order). The higher-half move needs the script authoritative.
Suite 27/27 on the LLD build.
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>
max_cpus, max_tasks, kernel/IST stack sizes, and timer_hz move from scattered constants into one config module. root.zig goes back to being just the boot contract. Values unchanged; any can become a -D build option later.
Daniel Samson
daniel