schinit: a launchd-shaped process 1

Milestone 1 of three: manifests, RunAtLoad, KeepAlive with throttling,
and reaping. Replaces the hardcoded fork-a-shell loop in cmd/init, which
stays in the tree for now.

Jobs are sectioned key=value files in /etc/schinit/*.job, kept in the
repo under etc/ and installed into the sysroot -- sysroot/ is generated
and gitignored, so anything written only there is lost on a fresh clone,
which is already true of /etc/passwd and should not become true of the
boot configuration. Unknown keys and sections are ignored rather than
fatal: a manifest written for a newer schinit must not stop this one
booting the machine.

Socket sections are parsed and recorded but not yet held. That is
milestone 2 and it is the whole reason for copying launchd rather than
sysvinit -- the supervisor holds the listener and starts the job on first
connect, which inverts the dependency graph and makes runlevels a
non-concept. The key exists now so manifests need not change later.

getdents64 is exposed to userland for this. The kernel has had it since
the Linux ABI landed, but nothing declared it in user.h or lib/usys.S, so
first-party programs had no way to list a directory at all.

Two things found by testing rather than reasoning:

  - setsid() gives a job its own session, and a session has no
    controlling terminal. The console then delivers input only to the
    foreground process group it tracks, so the shell came up, echoed
    every keystroke through the line discipline, and executed none of
    them -- indistinguishable from a hung shell. ControllingTerminal=yes
    claims it with TIOCSCTTY/TIOCSPGRP; off by default, since a daemon
    has no business seizing the console.
  - the first bootstrap() dropped /dev/input/event0-1 and most of /proc,
    because it was transcribed from the part of the old init that had
    been read rather than all of it. -Evdev caught it.

build/usbstick.img is built by `all` now: without it QEMU refuses the
-drive and the entire -Usb run produces no output, which reads as a
broken USB driver.

Seven suites green: base 27, Tty 51, Ps 32, Sock 64, Fb 36, Usb 31,
Evdev 29. make schfs-check passes.

.claude/memory/schunix-boot-splash-logo.md

@@ -16,7 +16,7 @@ one group. Verified rendering correctly on 2026-08-08.
 counter-intuitive part and it is a timing fact, not a preference: the kernel does
 not reach `vga_init()` until roughly the last 300ms of a ~2.8s boot, so a
 kernel-drawn logo appeared for about one frame before `console_takeover()` wiped
-it. Drawn from `splash()` in `boot/bios/stage2main.c` it is up for the whole boot.
+it. Drawn from `splash()` in `boot/stage2main.c` it is up for the whole boot.
 `kernel/dev/vga.c` keeps the same drawing code against the same mask
 (`vga_draw_logo`, `vga_logo_centered`) for things that want the mark *after*
 boot — the crash screen, eventually `schinit`. Don't "fix" the duplication by
@@ -35,7 +35,7 @@ for the one rule. 4 bits rather than 8 because the header is included by the
 **`STAGE2_SECTORS` was encoded in five places, not the three `docs/layout.md`
 claimed.** Raising it 24 → 48 to fit the 8 KiB mask proved it: the `dd seek=25`
 offset stayed behind and the kernel got written straight over stage2's tail.
-The five were `boot/bios/bootasm.S`, `boot/bios/stage2main.c`, the `dd seek=`, and *twice*
+The five were `boot/bootasm.S`, `boot/stage2main.c`, the `dd seek=`, and *twice*
 inside `tools/mkiso.sh` (its size assertion and `-boot-load-size`). It now lives
 only in the root Makefile, which passes `-DSTAGE2_SECTORS` and exports it to
 mkiso; the `#define`s left in the boot sources are `#ifndef` fallbacks. Hard

.claude/memory/schunix-iso-boot.md

@@ -18,7 +18,7 @@ protected mode before it reads the kernel. That rules out both El Torito
 emulation modes (hard-disk emulation exists only through the BIOS) and floppy
 emulation (2.88 MB cap). So:
 
-- `boot/bios/cdboot.S` — a separate stage 1 for optical media. `tools/mkiso.sh`
+- `boot/cdboot.S` — a separate stage 1 for optical media. `tools/mkiso.sh`
   passes `-boot-load-size 25`, so the BIOS loads cdboot *and* all 24 sectors of
   stage2 before anything of ours runs, putting stage2 at 0x7E00 exactly where
   `bootasm.S` would have. cdboot only records the medium and jumps.