| Filename | Latest commit message | Latest commit date |
|---|---|---|
5618164754
"Ą Ę Ś Ł Ż" drew as "?????" and the obvious diagnosis -- the font has no glyphs for them -- was wrong twice over. `struct vtcell.ch` was **one byte** holding a CP437 index, and the console mapped UTF-8 down to it on the way in. U+0104 does not fit in a byte. No font could have fixed that; the cell had to get wider first. So: `ch` is a uint32 codepoint, the mapping on the way in is gone, and the cell draws through kernel/dev/ttf.c against JetBrains Mono linked into the image. Cell size comes from the font's measured advance instead of a hardcoded 8x16. The grid costs 864 KB of BSS instead of 432 KB, which is the honest price of holding a codepoint per cell for six terminals at 240x75. The rasteriser needed three fixes before it could be trusted with this. **21 KB of locals on a 4 KB kernel stack.** `ttf_render` held an outline (512 points as three arrays) and a raster (1024 edges) as automatics. KSTACKSIZE is 4096. They walked off the bottom of the stack into whatever was underneath, which surfaced as user processes faulting on addresses they never touched and then a panic inside freevm() on an overwritten page directory. Nothing pointed anywhere near a font. **And then again, recursively.** load_outline() held a 4736-byte outline as a local *and recursed* for composite glyphs. Composite glyphs are exactly Ą, Ę, Ś, Ł, Ż -- so the second crash arrived the moment the first fix let Unicode reach the screen, looking like a fresh bug. Now a static outline per recursion level with a depth cap of 4 (the font's deepest real nesting is 2), and the leaf parse split into load_simple() so its 512-byte flag array is not multiplied by the depth. Worst chain measured from the object file: ~2.3 KB. Neither showed in tools/ttftest, which has an 8 MB stack. That is the standing hazard of one source file built for host and kernel: the host is most forgiving about exactly the resource the kernel is strictest about. **Component transforms were being skipped**, on the stated theory that a wrong transform is worse than none. It is not. `‘` in this font is the comma glyph with a scale of -1 -- a 180-degree rotation -- and the offset that ships with it only lands correctly after the rotation. Without it the mark went twelve pixels into a ten-pixel cell and was clipped away entirely, so the character read as missing from the font rather than as misplaced. F2Dot14 2x2 now, with SCALED_COMPONENT_OFFSET honoured. The glyph cache was ASCII-only, so every accented letter re-rasterised on every repaint: a screenful of Polish did hundreds of bezier flattenings per scroll where the same screenful of English did none. 95 reserved ASCII slots plus 224 shared slots keyed by codepoint, 64 KB pool. Verified 13680 cached renders byte-identical to direct ones across collisions and a pool flush. tools/ttftest speaks UTF-8 now. Iterating bytes meant it could only ever ask for ASCII, and ASCII is entirely simple glyphs -- it could not reach the code path that mattered. Also: resolvconf's success line moves behind /proc/bootmode, same rule as vgpud. A quiet boot opened with "resolvconf: nameserver 10.0.2.3" where the one line was supposed to be "Welcome to SchOS!". Failures stay loud. Verified on screen, not just on the host: Ą Ę Ś Ł Ż ć ń ó ź, Ω λ π Œ Ð Æ ß, ∞ ‘x’ → ≤ all render, panic=0 across four boots. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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| .. | ||
| architecture | ||
| branding | ||
| guides | ||
| history | ||
| plan | ||
| Website | ||
| licensing.md | ||
| README.md | ||
SchOS documentation
Four kinds of document, kept in four directories, because they answer four different questions and go stale at four different rates.
| architecture/ | What SchOS is | Present tense. Describes what is built and working. |
| plan/ | What SchOS will be | Future tense. Everything here is unbuilt. |
| guides/ | How to work on it | Imperative. Build it, test it, add to it. |
| history/ | Why it is the way it is | Past tense. Bugs whose cause is not visible from the fix. |
Plus two that belong to no category and apply to everything: licensing.md — read it before copying anyone else's code in — and branding/, which holds the marks and the rules for using them.
The rule that keeps this from rotting
When something is finished, it moves from
plan/toarchitecture/and is rewritten as a description of the thing rather than a record of building it.
A completed item is not a ticked checkbox. A ticked checkbox says the work happened; it does not say what the work produced, and six months later the checkbox is the only thing left and it explains nothing.
So finishing a piece of work has three steps, and the third is not optional:
- The code works and is tested.
- The plan entry is deleted.
- A description exists in
architecture/written for somebody who was not there — what it does, what shape it has, what it costs, and what it still does not do.
This is not bookkeeping. The tree has already proved it necessary: the network stack was finished, verified end to end, and for a month afterwards the only description of it anywhere was a checkbox in a roadmap, four levels of indentation deep, written in the past tense of somebody arguing for the work rather than explaining the result.
The "what it does not do" section is the one that pays. Every description in
architecture/ ends with one. A document that only lists a subsystem's
strengths is marketing, and the reader who most needs the document is the one
about to trip over a limitation nobody wrote down.
Start here
New to the tree → architecture/README.md, the system layer by layer, then guides/layout.md for where the files are.
Trying to build it → guides/building.md.
Wondering what happens next → plan/1.0.md, which is the finish line and the register of everything half-built. Then plan/README.md for the order.
About to start something new → the register, first. Nothing new starts while it has rows in it, and a row leaves only by being finished or deleted.
Something is broken and it feels familiar → history/. There is a good chance it is in there.
architecture/ — what SchOS is
| README | The system, layer by layer. Read first. |
| boot.md | Firmware to the first userspace process. |
| kernel.md | SchIFT: memory, processes, scheduling, traps, signals, SMP. |
| syscalls.md | The call table, and the Linux personality that lets real software run. |
| filesystem.md | The VFS, the buffer cache, procfs, mounts. |
| schfs.md | SchFS: the copy-on-write root filesystem. |
| devices.md | The device model, driver binding, the class vtables. |
| usb.md | xHCI, the USB core, and the class drivers. |
| graphics.md | Framebuffer, text rendering, console, and the crash screen. |
| terminals.md | The six virtual terminals, and how one is switched to. |
| networking.md | Drivers, lwIP, sockets — Unix and INET. |
| init.md | schinit, PID 1 as a role, and the job manifests. |
plan/ — what SchOS will be
| README | The three current decisions and the order they happen in. |
| 1.0.md | The finish line, and the freeze. What 1.0 contains, what is deferred, and the register of every half-built thing in the tree. |
| foundations.md | The kernel work everything else is blocked on. |
| wayland.md | The GUI stack, and what gets deleted to make room. |
| hybrid.md | Moving drivers out of the kernel. |
| schapi.md | The long-term API layering, and the compatibility promise. |
| roadmap.md | Everything else still open. |
guides/ — how to work on it
| building.md | Prerequisites and the build, per host. |
| testing.md | The harnesses, and what each one actually proves. |
| layout.md | Repository map, and how to add a program or a port. |
| adding-a-driver.md | Writing one, binding it, publishing its class vtable. |
branding/ — the marks
| README | Shift the logo, Guru the icon, SchCotie the mascot: what each is for, the colour rule, and why a raster is committed next to its SVG. |
history/ — why it is the way it is
| README | What belongs in here and what does not. |
| kernel.md | Bugs whose cause was nowhere near their symptom. |
| schfs.md | The filesystem's own, from the same period as its design. |
| moving-to-linux.md | The Windows-to-Fedora move, kept for the parts that recur. |
Writing one of these
Four conventions, all of them observable in the existing files:
State the cost. Every design choice gave something up. A document that does not say what is a document that will be argued with later by somebody who only sees the downside.
Prefer the measured number to the remembered one. "500 of 3565 files carry the advertising clause" is worth more than "some do", and it was worth the minute it took to count.
Write down the bug that shaped it. Half the non-obvious code in this tree is non-obvious because something failed once. If a design is strange, the strangeness is load-bearing and the reader deserves to know why before changing it.
No dates in headings. A date in a heading turns a description into a
changelog, and the description is the thing with a long life. Dates belong in
history/, where they mean something.