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docs/ was ten files where a plan, a description, a guide and a bug report all
sat next to each other. It is now architecture/ (what SchOS is), plan/ (what it
will be), guides/ (how to work on it) and history/ (why it is like this), with
an index that states the one rule holding it together: when something is
finished it moves from plan/ to architecture/ and is rewritten as a description
of the thing rather than a record of building it.
A ticked checkbox says the work happened. It does not say what the work
*produced*, and six months later the checkbox is all that is left. The network
stack proved the point: finished, verified end to end, and for a month the only
description of it anywhere was a checkbox four levels of indentation deep.
So roadmap.md went from 534 lines to 181 -- nothing deleted, the done work
graduated. Seven subsystems that were finished and undescribed now have
descriptions: boot, kernel, syscalls, filesystem, networking, graphics, usb,
init. Every one ends with "What it does not do", which is the section that pays;
a document listing only strengths is marketing, and the reader who needs it most
is the one about to trip over a limitation nobody wrote down.
schfs.md still opened with "phases 1 through 3 1/2 are done, phase 4 is next"
long after all five had landed. It is a description now, with the phase record
and the hard-won bugs moved to history/.
Three corrections found on the way, all load-bearing:
* projects/schcom/README.md claimed SCM_RIGHTS was done. There is no
sendmsg/recvmsg in the kernel at all, and an entire GUI plan rested on it.
* The root README said "No TCP/IP" months after the stack landed.
* history/kernel.md sec.7 was marked "in progress" on a problem that process
groups solved.
Also adds plan/1.0.md, which draws a finish line so the open list stops being
infinite, and marks schwm/ and schde/ superseded: in Wayland the compositor is
the window manager, so that split dissolves rather than being abandoned.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQ7Qx8E1q1M1bbCq8QLHS2
3.6 KiB
| name | description | metadata | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| schunix-boot-splash-logo | The boot logo pipeline, why the loader draws it rather than the kernel, and the STAGE2_SECTORS trap that consolidating it exposed. |
|
The boot splash shows the Assets/Schunix Small Logo.png mark (an SX monogram in
a ring) above the S C H U N I X wordmark and its accent rule, all centred as
one group. Verified rendering correctly on 2026-08-08.
The logo is drawn by the bootloader, not the kernel. This is the
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/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
deleting the loader's copy.
Pipeline: tools/mklogo.py (host Python, has its own PNG inflate +
un-filter) crops to the mark, box-downscales, normalises to full strength, packs
to a 4-bit coverage mask, and writes include/logo.h. Run make logo — it is
not a build dependency, and include/logo.h is committed, on the same
reasoning as include/font.h. The mask is coverage, not colour, so the palette
stays in schunix-console-tty's include/theme.h; the loader composites it in
SCH_FG because the source art is a silver gradient and the accent is reserved
for the one rule. 4 bits rather than 8 because the header is included by the
bootloader, where size is a boot constraint.
STAGE2_SECTORS was encoded in five places, not the three docs/guides/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/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 #defines left in the boot sources are #ifndef fallbacks. Hard
ceiling is 65 sectors — stage2 loads at 0x7E00 and must not reach the
multiboot kernel-search buffer at 0x10000 — and stage2main.c now
static-asserts that. See also schunix-iso-boot.
tools/splashshot.ps1 captures a burst of QEMU screendumps across early
boot and reports each frame's distinct-colour count, because the splash window
is too short to hit with a single guessed delay. It uses -snapshot plus
file.locking=off so it runs while an interactive QEMU has the images open —
booting from copies also works but means duplicating all 153 MB of
build/fs.img per run. Colour counts are the
assertion: ~2 means text console or blank, 18 means the 4bpp logo is up. If it
ever reads 156 again, something is drawing an 8-bit mask.
Two traps, both hit while doing this:
$(shell expr $(N) \* 512)in a Makefile does not work — make passes the backslash through, sh globs the*, and expr receives a directory listing. Make silently carries on with nonsense. Use$$(( ))in the recipe.make isowas failing when this was written, for unrelated reasons since fixed — see schunix-ramdisk-root-sizing.-boot-load-size 49is now verified: the ISO boots from optical media only.