| Filename | Latest commit message | Latest commit date |
|---|---|---|
c84d06c5b1
Gate 0's last item, "delete the cell grid" -- done as far as it should be, and the rest of it retired, which is the part worth explaining. include/text.h made the case against the grid in four charges: it cannot do variable-width glyphs, cannot position text off a multiple of eight, cannot anti-alias, and cannot hold a codepoint above 255. Every one of those was about the *drawing layer*, and every one is now false -- glyphs carry metrics, PSOGM positions text at arbitrary pixels, the TrueType path blends 8-bit coverage, and vtcell.ch is a uint32. What is left is a grid in vt.c, and deleting that would not modernise the console; it would stop it being a terminal. VT100 escapes address columns, TIOCGWINSZ reports rows and columns, and every program that draws a box assumes both. So the item is checked with its remainder rewritten to say what was actually wrong, rather than ticked as if the original wording had been carried out. **What was actually wrong was the duplicate.** gfx.c walked font_data and blitted glyphs its own way; text.c did the same job into a struct surface, for no caller but a sysrq self-test. Two implementations of bearings, coverage and clipping, which had to agree about a cell size only one of them was told had changed -- and they did not agree, which is why every line of PSOGM once drew the next character's bitmap underneath itself. There is one now, and the mechanism is the pleasing part: the console hands text_draw_glyph() **the cell as a surface of its own** -- same pixels, same stride, origin moved and bounds set to that cell. Clipping a tall ascender to its line is then the same bounds check that clips to the edge of a screen, and there is no second notion of clipping in the tree. `surface_sub()` is six lines and replaced fourteen of hand-written comparisons. The bitmap is reached through font_builtin() like any other provider, so the early console and the real one are one path with different metrics, and the `if (!cfont)` branch that walked the array is gone. gfx.c no longer includes font.h; text.c does, being the only file left that reads it -- which also retires the note in text.c explaining why it could not. struct surface gained a bpp, because gfx_draw_pixel handles 16, 24 and 32 and whatever replaces it has to as well. Zero means 32: a UEFI GOP has no other format and the loader publishes 32 unconditionally, so callers that do not care say nothing. One behaviour change, and it is the documented one: a codepoint the font cannot draw is now a substituted glyph rather than a blank cell. text.h argues for that directly -- "a missing glyph that draws nothing makes text silently shorter and the fault impossible to see". Verified by screendump: the console renders correctly, PSOGM renders correctly, and `echo t > /proc/sysrq` still draws its specimen through the surface path with the back buffer at 32bpp. Both supported configurations: one boot each, no traps, no panics, socktest and memfdtest green. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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| .. | ||
| architecture | ||
| branding | ||
| guides | ||
| history | ||
| niveus | ||
| 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 one mark: what it is for, the colour rule, why an icon and a mascot were removed, 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.