Sixty-five headers sat side by side in include/, so `#include "irq.h"`
said nothing about where irq.h was or what it belonged to, and errno.h,
stat.h and fcntl.h at the top shadowed the system's for any host tool
built with -I./include. They are in folders now -- arch/ core/ fs/
dev/ gfx/ net/ uapi/ (and ldls/ for the Linux driver layer) -- and
every include names the folder, as Linux's do: "core/proc.h".
Done mechanically and checked the hard way: the kernel built from this
tree disassembles identically to the one built from the tree before
it. The full image boots, and userland is the same set of programs.
Paths in docs and comments follow; docs/guides/layout.md has a table
of what is where, and tools/fix-includes.py rewrites old-style
includes from the folders in the tree, for code written before this.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Two bugs reported from actual use, plus a test harness that had stopped
testing.
init could be killed by Ctrl-C, taking the machine with it. SIGINT goes
to the foreground process group, init is pgid 1, and any window where
tty_fg_pgrp is 1 -- before a shell claims the terminal, after one exits,
or between the two while the key is held -- lands it on init. init has
no handler, so killed was set, exit() ran, and exit() panics outright on
initproc. Spamming Ctrl-C at a frozen program is exactly the input that
finds that window. POSIX and Linux both discard a default-action signal
for pid 1; init_ignores() now does the same, SIGKILL included, because
init is not killable from userspace on any Unix.
Everything was slow because BSIZE was 1024 while a SchFS block is 4096,
so every block cost four IDE requests, each with its own interrupt and
sleep/wakeup. exec() of the 800 KB toybox binary meant ~800 round trips.
The giveaway: `seq 1 200`, which touches no file and prints nothing,
cost the same 2.0s as `cat /bin/toybox`, and `ls | wc -l` cost exactly
double -- both dominated by loading the same binary twice.
BSIZE is 4096 now, one request per SchFS block, and NBUF is 256 blocks
(1 MB) rather than 90 KB -- smaller than the binary every command execs,
so nothing was ever still resident. ideinit() issues SET MULTIPLE MODE,
which is what makes a 4096-byte transfer legal: READ/WRITE MULTIPLE move
the drive's multiple count per interrupt and nothing had ever set it,
which is the real reason idestart() carried a sector_per_block > 7 panic.
seq 1 200 2.02s -> 0.06s
ls /bin 2.76s -> 0.68s
ls /bin | wc -l 4.68s -> 0.73s
And the harness. bootcheck called Find-Qemu from a param() default,
which is bound before any function in the body exists -- so it died on
its first line and printed an error containing neither "FAIL" nor
"Exception", the two things being grepped for. It had not run since it
was made host-portable. Worse, an earlier index-based edit had deleted
the Expect blocks for -Tty, -Usb, -Sock, -Ps and -Evdev, so five of the
seven modes asserted nothing at all. Restored, and the USB run gets its
own 16 MB build/usbstick.img: it had been pointed at build/fs.img, which
nothing builds since SchFS became root, so QEMU refused to start.
242 checks across seven modes, all passing, and make schfs-check green.
An x86-64 operating system built from xv6, now largely rewritten: SMP,
a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF
rasteriser, and a Linux-numbered syscall ABI.
No history before this point -- the tree was never under version control.
This commit exists so the rename that follows has something to undo to.
