| Filename | Latest commit message | Latest commit date |
|---|---|---|
30a0d0fbed
schdbgd ships Disabled, and its manifest explains why: a debugger that can read
the process table should not run on a machine whose owner never asked for one.
That default is right and has one bad consequence -- **the machines that most
need debugging are the ones you cannot get a shell on to enable it.** A laptop
with no serial port that stops before it can draw has nowhere to say why, and
`schinitd enable` needs a prompt that does not exist.
So `make DEBUG=1` adds a sixth entry to the F8 menu. Picking it toggles;
booting carries the choice through SCHBOOT_DEBUG_FLAG; the kernel publishes
/proc/bootdebug; schinitd starts the one job that flag may un-disable, with
the manifest's Args now naming 0.0.0.0 -- a debugger reachable only from the
machine being debugged is no use when that machine is the one that will not
talk to you.
Four decisions, since this is a network-reachable debugger:
compiled out, not hidden A release build cannot set the flag because the
code that would set it is not in the binary. A
menu item that is present and refuses is an
invitation to make it not refuse.
consent at the machine Somebody standing at the keyboard during boot is
the strongest consent this system can ask for and
the weakest one that is any use on hardware that
will not boot.
one job, named in schinitd Not a manifest key like EnableIfDebug: the general
version of "the boot menu starts things that ship
off" is worse than the specific one, and this way
what the flag can start is one readable line.
the kernel only publishes Nothing in the kernel behaves differently, so a
debug kernel and a release kernel are the same
kernel and a bug cannot be the flag's fault.
/proc/bootdebug is its own file rather than a second line in /proc/bootmode,
because bootmode's whole promise is that reading it is a string compare and
not a parser.
**Also: `tone` stopped lying.** On a machine with no sound card it reported
"the device will not take 16-bit samples", which sends you looking at the
format code instead of at the empty PCI slot -- /dev/dsp exists whether or not
hardware is behind it, and the ioctl is where the absence shows up. ENODEV is
now told apart from a format refusal.
Verified end to end: F8 -> item 6 -> boot -> schinitd says it is starting
schdbgd -> a client outside the VM connected to the forwarded port and ran
`dma`, getting the real arena dump back. The release build has no such entry
in the binary at all, and boots clean.
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.