3182da3965
Claude Code keeps per-project memory at <home>/.claude/projects/<key>/,
where <key> is the project's absolute path with every separator and the
drive colon turned into a dash. That makes it both rename-fragile and
machine-specific, and this project has hit each of those once:
- D:\DEV\Schunix -> D:\DEV\SchOS changed the key, and 43 memories were
invisible until moved across by hand.
- Development happens from Windows and from Linux, and each looks in a
different place for the same checkout.
Committing .claude/memory/ fixes both -- git carries it across renames
and between hosts -- and `import` puts it wherever the local machine
expects. .claude/settings.local.json stays ignored: those are per-machine
permissions.
The colon maps to a dash rather than being dropped. Deleting it gives
D-DEV-SchOS, which matches nothing and silently finds zero memories; that
was the first attempt. On Git Bash the key comes from `cygpath -w`,
because Claude Code is a Windows program and sees D:\DEV\SchOS, not
/d/DEV/SchOS.
52 lines
2.7 KiB
Markdown
52 lines
2.7 KiB
Markdown
---
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name: schunix-sockets-and-evdev
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description: "Unix domain sockets and /dev/input evdev both work; the one lock rule, the names-not-in-the-VFS tradeoff, and where the syscall numbers went"
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metadata:
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node_type: memory
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type: project
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originSessionId: 9d8a2aef-bcf0-47a0-96c6-f706efab4a95
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modified: 2026-08-05T07:12:20.950Z
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---
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Unix domain sockets (`kernel/net/unix.c`, `include/socket.h`, `kernel/sys/sys_net.c`)
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and raw input events (`kernel/dev/input.c`, `include/input.h`) are both done and
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verified — `tools\bootcheck.ps1 -Sock` and `-Evdev`.
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**One lock for the whole socket table, deliberately.** A pipe gets a lock per
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pipe because every operation touches one object; a socket operation touches
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two, and per-socket locks need an ordering rule every path obeys or they
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deadlock. Worse, a reader testing `peer_closed` under its own lock while the
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closer sets it under the peer's has no interlock and sleeps through its own
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wakeup. Don't "optimise" this into per-socket locks.
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**Socket names live in a table, not the filesystem.** `ls -l /tmp/schcom` will
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not show an `s` and `unlink()` of a socket path returns ENOENT. Fixing it
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properly means a new inode type through both filesystems, iget, dirlookup and
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stat — a VFS change, not a socket change. Everything that matters works.
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`connect()` deliberately does **not** wait for `accept()`. A queued connection
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is already established on Unix; blocking would deadlock any server that
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connects to itself.
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The syscalls had real Linux numbers assigned (41/49/50/43/42 and friends).
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They were `NO_LINUX` stubs before, which meant a musl program calling
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`socket()` got "bad syscall" from the ABI translation and never reached the
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stub at all — same trap as [[schunix-shm-and-mmap]]. `shutdown` is registered
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as `sockshutdown` because Schunix already has a native `shutdown` that powers
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the machine off.
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**evdev:** `/dev/input/event0` (keyboard) and `event1` (mouse), major 7, Linux
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`struct input_event` layout. Fed by the PS/2 keyboard, the PS/2 mouse and USB
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HID. The console keeps its own path — both consumers see every key, so keys
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pressed during a test also land on the shell's input line.
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Two things that are not obvious:
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- Below 0x54 a Linux keycode **is** the AT set-1 scancode, so the PS/2 path
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needs no table. USB HID does need one (`hid_keycode[]`), because HID numbers
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keys by position and the AT set numbers them by matrix wiring order.
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- A full event ring drops the **oldest** event. Dropping the newest is the
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obvious choice and it is wrong: the event most likely lost is a key release,
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and a lost release leaves the key held down forever.
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See also [[schunix-console-tty]], [[schunix-framebuffer-device]],
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[[schunix-verify-by-driving-shell]].
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