On the Ryzen 4600G desktop and the ASUS TUF A15, AMD's GOP "sets" the
smaller modes without leaving the panel's native timing and reports the
mode's own row length. Every check the loader made passed, and the screen
showed three or four squashed copies side by side (1920/640, 2560/640).
Nothing the firmware reports can tell such a mode from a real one.
So a mode change now asks "Keep this resolution?" in the new mode and keeps
it only on Enter within ten seconds. On a mode that does not really work the
question cannot be read, and the old mode comes back by itself.
And the reason to want a smaller mode was the text: the console font was a
fixed 16 px, unreadable on a 1440p monitor. It now scales to about 45 rows,
16 to 40 px per em, on whatever mode the firmware booted in.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
A Linux module is built with -mcmodel=kernel and can only reach addresses
in the top 2 GB, where this kernel is not linked. So the kernel image is
mapped a second time at LDLS_KALIAS, with a vmemmap area and a module area
beside it, in one PDPT shared by every address space. Nothing loads a
module yet; this is the address-space groundwork, set up at every boot,
and include/ldls/ is the interface the loader will use.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
A release on the Forgejo carries the ISO and its sha256. The server is a
small VPS shared with other projects, so publishing a release deletes the
ISO from every older one; their notes, tags and checksums stay, with a
line saying how to rebuild the image from the tag.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The README led with a wallpaper and described the system of two months
ago: no desktop, no dynamic linking, a handful of drivers. It now leads
with Shift and covers Xorg and Window Maker, apk and Alpine packages,
SCFF, HTTPS, the storage, network and input drivers, and the machines it
has booted on. "Not there yet" lists what is actually missing today:
threads, udev, EHCI, touchpad gestures, an installer.
The numbers -- lines of code and of comments, syscalls, drivers, packages,
commits -- come from tools/python/stats.py, which rewrites them in the
README and on the website between stats markers instead of somebody
typing them once and letting them go stale.
.gitattributes keeps the generated font and logo tables and the vendored
Niveus out of the repository page's language bar.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
A laptop's touchpad is on the chipset's I2C bus, found only through ACPI
(PNP0C50 / ACPI0C50), and SchOS had no I2C at all, so the touchpad of
every recent laptop did nothing.
kernel/acpi/i2c_hid.c drives the DesignWare I2C controller every x86
chipset uses (AMDI0010 on Ryzen) by polling, speaks HID over I2C to the
device the _DSM points at, and feeds the reports through the USB HID
parser. On AMD the interrupt pin's level is read every tick, so a report
is read exactly when one is waiting; elsewhere the input register is polled.
The touchpad is driven in mouse mode, which it starts in after a reset:
motion, clicks and taps become /dev/input/event1 like any mouse. The HID
parser now prefers a descriptor's relative pointer over an absolute one
for this, and takes descriptors from transports other than USB.
Untested on hardware: QEMU emulates no I2C touchpad.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Xorg uses VTs only when stat("/dev/tty0") reports Linux's tty major 4.
SchOS's terminals sit under major 1, so X ran on no VT at all: the console
kept drawing over it, Ctrl+Alt+F-keys did nothing, and nothing ended the
session. stat now reports terminals under Linux's numbers.
startx picks the VT only when uname says Linux, so root's xserverrc passes
the current one itself. An xorg.conf.d file names X's input devices, since
Alpine's Xorg looks them up through udev and SchOS has none yet.
Alt+F1..F6 and Ctrl+Alt+F1..F6 now switch terminals as on Linux, alongside
the settable chord. USB keyboards gain arrows, Home/End/PgUp/PgDn/Ins/Del
and the switch keys, which the PS/2 path always had.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
SCFF, the SchOS Compressed File Format (include/fs/scff.h), is a block
image cut into 128 KB chunks, each its own zstd frame, behind an index.
tools/mkscff writes it from fs-ram.img on every core (-19, 11 s) and
checks each chunk decompresses to itself. The kernel carries the .scff
as its ramdisk and unpacks a chunk the first time a block in it is
read; zero blocks share one page. The kernel and the ISO are the
compressed size, and the root costs memory only for what is touched.
See docs/architecture/scff.md.
zstd 1.5.7 comes from ports/zstd like uACPI: the decoder is compiled
into the kernel at -O2, with a static context and a 64 KB stack of its
own, and mkscff builds the whole library from the same release.
world now has xorg-server, the fbdev and evdev drivers, xinit, Window
Maker, xterm and DejaVu, and /root/.xinitrc runs wmaker. That root is
358 MB, 102 MB as SCFF.
The ISO no longer carries the root a third time as an ISO 9660 tree,
which nothing read. schos.iso: 1389 MB -> 318 MB. El Torito keeps its
own copy of the EFI image, the layout real machines have booted.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
syscall_entry put the frame at kstack + 4096 - 16, from when a kernel
stack was one page. It has been two since, so every syscall ran in the
bottom 4 KB while traps used the top, and a deep enough read -- startx
exec'ing through the new compressed ramdisk -- ran over the canary at
kstack[0]. The frame now sits at the top of KSTACKSIZE, where allocproc
and the TSS already put it, and exec's user-rsp slot moves with it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
busybox wget hands TLS to ssl_client over a socketpair and then does
shutdown(SHUT_WR). That cut the AF_UNIX link both ways, so ssl_client's
reply was a SIGPIPE and every https:// download hung. SHUT_WR is now a
half-close: the peer reads EOF and can still answer. TCP sockets get
shutdown() at all (tcp_shutdown for the FIN); it used to do nothing.
- exec keeps ignored signals and the signal mask, as execve(2) says.
- /proc/<pid>/fd: a link per descriptor -- the path it was opened by,
socket:[n], pipe:[n], anon_inode:[eventpoll]. /proc/self too. The
global inode bit moves above pid << 8; at 0x10000 it was /proc/256.
- fstat on a socket or pipe answers S_IFSOCK / S_IFIFO instead of EINVAL.
- poll, select and epoll wake as soon as a pipe, socket or input device
changes, not on the next tick.
- Pipes are 64 KB of lazily allocated pages, copied in blocks, with
PIPE_BUF atomicity: 300 MB through `yes | head | wc` in 7 s.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Xorg finds its VT through /dev/tty0, and without one ran on none: the
console went on drawing into the framebuffer over the X screen. tty0 is
the terminal on screen, as on Linux. FBIOPUTCMAP succeeds, as it does on
a true-colour Linux framebuffer, instead of 256 logged errors per start.
schos-base gives root a .xserverrc with -dumbSched, Xorg's switch for
input on the main loop: SchOS has no threads, and Xorg crashed in
pthread_join on its input thread when the first client left. It adds
the hostname to /etc/hosts, so xauth can resolve schos:0.
zsh loses PROMPT_SP: on a serial terminal narrower than the console its
padding wrapped and left a # above every prompt. bootcheck knows zsh's
prompt and matches without colour codes, so busybox's ls reads as text.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
alarm() and setitimer() stored a countdown nothing counted down, so no
timer has ever fired; setitimer and getitimer were also registered with
no Linux number. alarmd now posts SIGALRM on the tick, while any process
has a timer armed. busybox's ping, /bin/ping on the Alpine root, sends
every request after the first from its SIGALRM handler.
It also opens SOCK_RAW, which was EPROTOTYPE. A raw ICMP socket is now a
ping socket whose reads start at the IP header. And a blocked socket
call gives up for a signal with a handler, not only for a kill: the
alarm woke recvfrom, and the wait put it straight back to sleep.
For Xorg: AF_UNIX abstract names, which read as the empty path and so as
EADDRINUSE ("server already running"); and getsockname and getpeername,
which did not exist, so libxcb sent no cookie and the server refused
every client.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The live root was a fixed 96 MB image in the kernel: 60 MB of zeros on
the ISO, twice, and room for 60 MB of packages whatever the machine had.
Now the image is only what the root holds, plus slack, measured by
building it once large. Past its end the ramdisk goes on to half of the
memory free at mount, as pages taken the first time each block is
written; an unwritten block reads as zeros and costs nothing. SchFS
keeps no free-space map on disk, so growing a volume is a larger total
before open builds the map: grow_to, set for the ramdisk root.
8 GB machine: a 4 GB root, Xorg installed into it in 77 s with 7.6 GB
still free. The ISO is 172 MB instead of 344.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
make qemu and make iso went on building sysroot/ as the root while only
make aroot built the apk one. Both now come from the apk root: a 1 GB
schfs.img for make qemu, and a 96 MB ramdisk for the ISO, 35 MB of it
the base system and the rest room for apk add on the live system.
sysroot/ is what schos-base is packaged from, not a root of its own.
hwdata leaves the ramdisk exclude list: it is Alpine's package now, and
a root missing files apk's database lists is one apk has to repair.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Nix's compiler wrapper adds -fPIC and friends to every compile. The
kernel is freestanding at fixed addresses, and clang refuses -fPIC for
the UEFI loader's PE target outright, so a plain make in nix-shell
stopped at BOOTX64.EFI.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
make aroot builds a SchFS root from Alpine's minirootfs, the packages
ports/alpine/world lists, and SchOS itself as the signed apk package
schos-base, in its own repository inside the root. apk add installs from
Alpine; apk upgrade updates both. Booted: zsh is Alpine's, apk update
sees 28669 packages, apk add htop works, and so does xorg-server.
world.lock pins every package with its sha256; a build fetches only what
dist/alpine/ lacks and never looks for newer versions. make alpine-lock
is the one step that does.
Alpine's zsh, busybox commands and hwdata replace SchOS's copies; SchOS
keeps its own tools, toybox's other commands, and static mksh, which
schinit's recovery shell now tries first.
Also: the dependency-file include matched Alpine's usr/lib/sysctl.d, a
directory, and stopped every make. See docs/plan/alpine.md.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Measured against the host fetching the same 67 MB from Alpine's CDN at
11.5 MB/s, SchOS managed about 120 KB/s. Three causes:
- The receive window reopened when data entered the socket buffer,
before the reader drained it; lwIP then refused segments and the
sender waited on retransmission timers. It reopens on read now.
- The e1000 receive ring held 16 frames, so a full window arriving back
to back lost everything past the sixteenth. 256 now.
- Without window scaling the window stops at 64 KB, one window per
round trip. Scaling on, 256 KB window, 512 KB socket ring (a power of
two, which the free-running indices need), copied in blocks.
Now 5.8 MB/s for the same file, and apk update in about two seconds.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Found by running Alpine's apk on SchOS, one failure at a time:
- chroot(2) was a stub returning EPERM. Each process now has a root:
where an absolute path starts and where .. stops. Mounts remember
whose root they were made under, and a walk leaves a mount by the way
it came in, so one filesystem can be mounted twice.
- devtmpfs and proc mounted only on /dev and /proc, whatever the target;
a chroot got "already mounted".
- mmap never reused freed address space, so musl's malloc used up the
256 mapping records while 780 MB were free. A mergeable mapping now
goes straight after an anonymous one whose end has room.
- unlinkat returned -1 (EPERM) where apk expects ENOENT, and renameat
was an old copy of rename: no replacing the target, and v1 dirents
written into SchFS. Both now share rename's implementation.
- execve runs #! scripts, and says ENOEXEC for what it cannot run.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
There were none: fcntl answered F_SETLK with EINVAL and flock was not a
system call. Alpine's apk, which runs unmodified on SchOS through
Alpine's own musl, locks its database before reading it and stopped
there.
kernel/fs/lock.c keeps one table of advisory locks keyed by (dev, inum):
flock() for the whole file, owned by the open file description;
F_SETLK/F_SETLKW/F_GETLK for byte ranges, owned by the process and
released when it closes any descriptor on the file or exits; and the
F_OFD_* forms, ranges owned by the description. flock and record locks
do not see each other, as on Linux. Waiters sleep until any release and
are interrupted by a signal.
cmd/locktest checks each between a parent and a child, including range
splitting, F_GETLK's report, and a blocked waiter being woken.
shell.nix gains pkg-config, meson, ninja, m4, bison, flex and xz, for
the X ports.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
xorg.md replaces wayland.md as Gate 3's plan: what is built, and the
ports left in order. 1.0.md's foundations row is brought up to date.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Xorg on a framebuffer -- the fbdev video driver, the evdev input driver,
libpciaccess -- asks the kernel a fixed set of questions before it draws
anything, and gives up on the first wrong answer. These are those
answers.
evdev: EVIOCGVERSION, GID, GNAME, GPHYS, GUNIQ, GPROP, GBIT, GKEY, GABS,
GREP and the accepted setters. Xorg and libinput decide what a device
*is* from the capability bitmaps; /dev/input/eventN answered only
EVIOCGRAB, which reads as no device at all. Each device's bitmaps are
its defaults plus whatever it has reported, so a USB tablet makes the
pointer absolute.
fbdev: FBIOPUT_VSCREENINFO succeeds for the mode already set, as on
Linux -- the fbdev driver sets it every time it starts -- and still
refuses any other. FBIOPAN_DISPLAY to the origin; FBIOBLANK.
The console: KDSETMODE(KD_GRAPHICS) stops it drawing on a terminal,
KDSKBMODE(K_OFF) stops keys reaching its tty, and VT_PROCESS now does
the switch handshake: leaving the terminal sends relsig and waits for
VT_RELDISP, arriving sends acqsig. A terminal whose owner has died goes
back to the kernel whole, so a crashed X cannot leave the console dead.
/sys: boot_vga, a writable enable, and graphics/fb0 under the display
device, which is how the fbdev driver pairs a card with /dev/fb0.
ports/linux-headers: <linux/*.h> into musl's prefix, from sabotage-
linux's kernel-headers 4.19.88-2. Its checksum is recorded from the
first download; upstream publishes none.
cmd/xready makes each call and checks the answer, including the switch
handshake on tty2 and an owner that dies holding it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Every page table SchOS built -- the loader's, which the kernel starts on
and the other CPUs start through, and the kernel's own direct map and
device window -- mapped memory in 1 GB pages. Intel's desktop CPUs
before Haswell do not have them, and there the PS bit in a PDPT entry is
reserved: the first access after the switch is a page fault that cannot
be handled either. An HP all-in-one with an Ivy Bridge i3 showed "Placing
and starting the kernel" and reset.
Both now check CPUID 0x80000001 EDX bit 26. Without it the loader maps
the low 4 GB through four page directories of 2 MB pages, placed below
the kernel where nothing reuses them, and keeps the staged kernel
segments below 4 GB; the kernel gives each gigabyte of its direct map
and of ioremap() a page directory of its own.
Neither KVM nor QEMU's emulator enforces the reserved bit, so the fault
itself could not be reproduced here. With the fallback forced on, the
kernel boots at 2 and 8 GB, both CPUs start, and evtest passes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
An ASUS TUF A15 booted with its internal keyboard dead and a USB one
fine. These AMD laptops' firmware describes IRQ 1's polarity wrongly --
Linux keeps a quirk list -- and an edge line programmed the wrong way
up never fires: the controller holds its byte, and only the interrupt
that never comes would read it.
irq_watch() lets a driver say how to ask its device whether something
is waiting. The poller asks every tick; 50 ms of waiting with nothing
delivered turns the line's polarity over and drains the device, which
re-arms the edge, and if it still says nothing the line is polled.
Both are announced. The keyboard and the PS/2 mouse are watched.
ISA lines now also take their mode from the MADT's override entries,
which were parsed and never read.
Tested in QEMU, which ignores polarity on edge lines, with the keyboard
line masked: the first key turns it over and typing works; masked again
after the flip, it is polled and typing still works.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The staged segments were copied home after ExitBootServices by the
loader itself -- on code, a stack and a copy list the firmware had
placed wherever it liked. On an HP all-in-one some of that was in the
kernel's range: "Placing the kernel", then a triple fault and a reset.
The copy and the jump now run from one page below the kernel's lowest
address, allocated as loader code before the firmware exits: a short
position-independent routine, the copy list, and a stack. It switches
to the loader's page tables and its own stack before copying anything.
Called sysv_abi, because UEFI code is the Microsoft convention and the
first try loaded the framebuffer address into rsp.
The framebuffer address handed over in rbx is 64-bit now too; the
kernel already read the full one from the hand-off block.
Also write.sh: writes schos.iso to a USB stick, after showing the
device and asking for its name to be typed back; refuses partitions,
the system disk and non-removable disks; reads the result back.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The set libwayland's event loop is made of, in kernel/sys/sys_event.c:
four kinds of descriptor with no inode, FD_EVENT, that read() drains
and poll() reports on. They were table entries returning ENOSYS that
read as done.
epoll registers (descriptor, file) pairs, so a closed descriptor
leaves the set; level- and edge-triggered, EPOLLONESHOT. Waiting is
poll()'s, a tick at a time. The old eventfd and signalfd numbers (284,
282) were aliased to the new calls and read flags from a garbage
register; they are their own entries now, with epoll_create and
epoll_pwait.
cmd/evtest checks each, then all four in one set. The plans are
brought up to date: everything Wayland was waiting on is built except
setsockopt.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
A program that names an interpreter in PT_INTERP gets it loaded too, at
the bottom of the mmap area, and started instead -- with AT_PHDR,
AT_PHENT, AT_PHNUM, AT_BASE and AT_ENTRY to find the program by. ET_DYN
images are placed at a base: the interpreter there, a PIE program where
a fixed one would go. Static musl programs get AT_PHDR now as well,
which is how musl finds their TLS template.
mmap(MAP_FIXED) of a file handed back zeroed pages whatever the
descriptor said, and kept no record of them, so fork() did not copy
them. A dynamic linker maps every library segment after the first that
way. Fixed mappings now read the file and are recorded wherever no
mapping already covers them.
musl is built shared as well as static, and libc.so ships as
/lib/ld-musl-x86_64.so.1 -- libc and loader in one file. Every port
still links -static on purpose.
cmd/dynhello is the test: against libc.so and a library of its own,
checking TLS, the heap, and a fork whose child still has both.
mprotect is accepted and not enforced yet.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
sigsend() ended a process for a default-fatal signal (SIGUSR1, SIGTERM,
SIGINT...) on arrival, whatever its signal mask said. Blocking is
exactly the promise that it will not: the signal waits until it is
unblocked, or until the program takes it some other way -- which is
what signalfd is, and how this was found.
A blocked signal is now only made pending. If it is later unblocked
while still pending, deliver_signals() applies the default action
then. SIGKILL cannot be blocked, as before.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
From 1 MB the 34 MB kernel ran across 8 MB, where OVMF keeps ACPI NVS
memory that outlives the firmware -- so it was overwritten on every
boot, after ExitBootServices. Firmware leaves its leftovers low; above
16 MB is where a machine is most reliably empty.
KERNPHYS in memlayout.h, and kernel.ld agreeing with it. Nothing else
named the old address. Under OVMF the range is now only boot-services
memory: staged, copied home after the firmware exits, no warning. Boots
as a CD and as a USB disk, 1 and 4 CPUs.
The 15 MB below the kernel is not given to the page allocator yet.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The kernel goes at fixed physical addresses, 1 MB to about 34 MB with
the RAM disk inside it. When AllocatePages refused part of that, the
loader said "could not reserve" and read the kernel there anyway -- over
the firmware's own memory, with the firmware still running on it. An HP
all-in-one from 2012 froze at the start of the loading bar.
Now every free page of the range is claimed first. A segment wholly on
claimed pages is read straight home; one that is not is read into a
buffer elsewhere and copied home after ExitBootServices, when
boot-services memory is ours. Memory under the kernel that outlives
the firmware (ACPI NVS, runtime services) is named, and so is the loader
or its stack sitting in the range.
Segments are read a megabyte at a time, so the bar moves through the
RAM disk and shows where a machine stopped.
Under OVMF the data segment (over ACPI NVS and boot-services data at
8 MB) is now staged, and it boots both as a CD and as a USB disk.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
From a clean tree the first make failed with "no rule to make target
build/lwip/core/init.o": a pattern rule is only used when its
prerequisite exists or can be made, and before the unpack lwIP's .c
files were neither. A second make worked, which is why it went unseen.
The unpack now claims the .c files. And sysroot-install waits for it,
because its own make -C ports unpacked lwIP too, and two unzips under
-j collided.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
-isohybrid-gpt-basdat does nothing without an MBR template, so the ISO
had no partition table at all: written to a stick, it was a CD
filesystem at sector 0. AMI on a B550 (and OVMF) read El Torito off any
block device and booted it anyway. An HP all-in-one from 2012 looks for
an EFI system partition on a USB disk, as the spec says to, found none,
and listed the stick under Legacy only.
The FAT image now goes in a second time as MBR partition 2, type 0xEF,
and is FAT16 by cluster count rather than FAT12, the type old firmware
reads worst. Booted under OVMF both as a CD and as a USB disk. The ISO
also rebuilds when mkiso.sh changes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
- schinit, schinitd and vgpud build every message from pieces, one
write() each, so a job starting on another CPU landed mid-line:
"schinitd: starting vgpud: os.schos.resolvconfno virtio-gpu on this
machine". They now collect a line and write it at the newline;
resolvconf's verbose line is one write with its prefix.
- The ACPI SCI registers IRQ_QUIET. A desktop's SCI never fires, and the
poller took two seconds of silence for a misrouted line ("irq 9:
nothing has arrived on it") and called the handler every tick. A line
is only exempt while every handler on it is quiet.
- The loader claims each segment from where the last one's claim ended,
so two segments sharing a page no longer ask for it twice. When a
claim is still refused, it names the memory-map entries in the way.
- Stale divesymlink() declaration gone; the kernel.md struct table
re-measured (inode, buf and file pools grow from slabs now).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Home:
- The hero stands on a light from the upper left and a pool of the
accent, mixed from Niveus tokens so it follows the theme. The mark sits
in an .nv-tile key under a slogan: "Every layer its own -- from the
first instruction to the last pixel."
- New section headings: "A teaching kernel that outgrew its lessons",
"Measured, not marketed", "One ISO. One stick. Your disks untouched."
- A Wallpapers section with the four new ones, each downloadable as a
4K JPEG or as SVG. The four-card grids are two across, so none is left
alone on its row.
Docs reader:
- An index filter, a breadcrumb with reading time and source path,
code blocks framed with a language strip and a Copy key, previous and
next keys at the foot, a reading-progress hairline, and the contents
entry lit for the section on screen.
- The index lists the documents it was missing: scheduler, FAT, audio,
LDLS, debugging and the hardware report.
- On a phone the page is no longer wider than the screen (a pre block
was sizing the grid's auto column), and the index folds away.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
tools/wallpapers.py writes them from the Shift geometry, so they follow
the mark: Graphite (the default), Strata, Porcelain (light) and Dial.
Each is a 3840x2160 SVG with a JPEG render beside it. JPEG is the right
format for gradients under grain, and the branding README now says why
this is the one exception to its no-JPEG rule.
Removed: wallpaper1 (drawn flat, and built on the retired Guru mark),
the site's unused copy of it, and the two superseded wordmark PNGs. The
root README showed one of those, and now shows Graphite.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Three fixes for real machines that broke at any resolution but 800x600:
- kmain() took the loader's framebuffer address as uint32, and
vga_fb_init() re-published the scanout from that and the 16-bit VBE
block. An aperture above 4 GB moved the console onto the wrong memory
right after the vga: line. Both now use the loader's 64-bit display
block, mapped with ioremap().
- The loader mirrored onto the console splitter's GOP, which forwards to
the primary itself, and onto GOPs that share the primary's aperture.
After a mode change that rewrote the screen over itself with another
mode's stride. Handles without a device path and overlapping apertures
are skipped, and a mode change re-matches the remaining mirrors.
- A mode whose reported size, stride or aperture does not add up after
SetMode is refused, and the loader returns to the previous one.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The marks are now drawn the way Niveus draws its keys: one light from the
upper left, gloss on the faces that catch it, a specular line on the edges
that face it, and soft contact shadows.
- Shift: shaded slabs, each casting onto the one below. shift-mask.svg is
untouched, so the kernel's logo.h coverage mask is unchanged.
- Uberblock: bevelled slots in a groove; the newest slot and the root glow.
- USB stick: moulded body, steel connector, a lit activity LED.
- Pride flag: cloth folds and a hem over the flag's own colours.
The pages use the components the new Niveus added: both terminals are
.nv-window frames, the origin and first-boot sequences are .nv-steps, the
numbers are a .nv-stat-group, and each feature card has an .nv-tile glyph.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The vendored copy of Niveus, the site's design system, brought up to
the current upstream (github.com/Nexoniarz/Niveus, 2026-10-18). The
tree under docs/Website/niveus is upstream's byte for byte.
.gitattributes says `* text eol=lf` and listed the binary types it
knew, and woff2 was not one of them: Niveus's InstrumentSans-Italic
had a CR LF pair in its compressed data, and committing it turned that
into LF and the font into garbage. woff, woff2, otf, ico, gif, webp,
pdf and wasm are binary now.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
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
Nothing ever saved the FPU and SSE registers on a context switch.
musl's memcpy, the compiler's struct copies and any arithmetic on
doubles keep live values in %xmm, so two processes sharing a CPU wrote
over each other's: two shells counting in a loop on one processor took
a NULL+8 page fault within seconds, at a different rip every time. It
reproduces on kernels from before this week too -- it had always been
there, and every crash nobody could explain was a candidate.
sched() now fxsaves the process leaving the CPU and scheduler()
fxrstors the one arriving. A new process starts from the ABI's state
(FCW 0x37F, MXCSR 0x1F80), fork copies the parent's live registers,
exec resets them, and a signal handler's are put back by rt_sigreturn
so the interrupted code finds what it had.
The kernel was free to use %xmm too -- GCC vectorised struct copies
and memset into 153 instructions of it -- so an interrupt could
clobber the registers of the program it interrupted with no switch at
all. Kernel, lwIP and uACPI objects are built -mgeneral-regs-only now
and the image has none; cmd/ keeps SSE.
Checked under QEMU: three concurrent loops three times over, on 1 CPU
and on 4, no faults; before, every run faulted.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The scheduler was xv6's round-robin: run everything RUNNABLE in slot
order and yield on every timer tick. Slot order is not fairness, a
process alone on a CPU paid a full context switch a hundred times a
second to be handed straight back to itself, and there was no way to
say that one thing mattered more than another.
Every process now carries vruntime, the CPU time it has used divided
by its weight, and the scheduler runs the runnable process with the
smallest. Fairness and interactivity both fall out of that one rule;
nice is a weight, 1.25x per level as UNIX has always had it. A slice
is 20 ms shared among the runnable processes, never below 2 ms, and
the timer tick preempts only once it is spent. A process waking from
a long sleep is brought up to min_vruntime less one period, so it is
scheduled promptly without being owed everything it slept through;
fork inherits vruntime, so forking does not reset a debt.
getpriority/setpriority are real, with Linux's offset of 20 on the
return; /proc/<pid>/schedstat and the ctxt_switches lines of status
report what the scheduler did. docs/architecture/scheduler.md has the
reasoning, including why the run queue is still a scan of ptable.
This was written in an earlier session and left uncommitted. Finished
here: a signal waking a sleeper goes through the same vruntime floor
as wakeup() does, and sched_yield() yields -- it returned 0 doing
nothing, harmless while every tick was a yield and a spin of a whole
slice once ticks stopped being one.
Checked under QEMU on 1 and 4 CPUs: a nice 10 loop beside a nice 0
one gets about a tenth of a shared CPU, and a command typed meanwhile
answers in 26 ms.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Every page of RAM went onto the free list at boot, which means writing
each one -- a link, and kfree()'s 4 KB of junk -- before the first
process ran: 64 GB of memset on a 64 GB machine to say it was free.
Memory nobody has used yet is kept as a cursor and an end per region
now, and kalloc() takes from those once the list of given-back pages
is empty. A page is first touched by whoever asked for it.
That makes the cap on RAM cheap to raise, and PHYSTOP_MAX goes from 64
to 256 GB, which still leaves 248 GB of the kernel PDPT for device
windows. MEMREGION_MAX goes from 32 to 64 for the firmware maps that
cut RAM into many pieces.
kalloc_free_bytes() walked the whole free list under the allocator's
lock -- two million links on 8 GB, every second top or fastfetch was
running, with every CPU that wanted a page waiting behind it. It reads
a counter now. And the buffer cache, which keeps what it grows to, is
reported as Buffers in /proc/meminfo and sysinfo(2) rather than as
memory used by nothing.
Checked under QEMU at 1, 2 and 6 GB: MemFree right, zsh splitting
200000 words, fork loops, a 74 MB write.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The fixed tables that a bigger machine than the one they were written
on reaches first, each raised to where it costs little:
NPCI 64 -> 256 a desktop with cards and Thunderbolt passes 64,
and the devices past it -- often the disk or
NIC last in bus order -- were ignored; 44 KB
NSOCK 32 -> 128 Unix sockets, which a desktop session uses by
the dozen; 4.9 KB each, 470 KB in all
NDEVICE 32 -> 128 120 bytes each
NIFDEV 16 -> 64 one dock is a hub, Ethernet, audio and a card
reader at two or three interfaces apiece
NETIF_MAX 4 -> 8
Device names took one digit and clamped there, so the tenth device of
a kind and every one after it was named "...9". Two digits now.
Checked under QEMU with two bridges of test devices: 68 functions,
all in lspci, /proc/pci and /sys/bus/pci.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
NCPU was 16, under what a desktop has today. 64 costs 48 more TSS
I/O bitmaps and scheduler stacks, about 800 KB of BSS. Past 254 the
APIC would need x2APIC mode, which is a separate change.
With more than 16 there were two other ceilings. sched_getaffinity
wrote "CPU 0" and returned 0, and musl clears every byte past the
count returned -- so the mask came back empty and nproc, make -j and
sysconf(_SC_NPROCESSORS_ONLN) all said 1, on any machine. It returns
the mask of processors that started, and its size, now. And /proc
rendered every file into 2 KB, which /proc/cpuinfo ran out of at the
eighteenth processor without a word; /proc/pci, /proc/interrupts and
/proc/mounts were each one bigger machine from the same cut. There is
one 64 KB buffer for it now behind a sleeplock, since there is no
allocator for contiguous pages, and the generators that write raw
are given the real capacity instead of a constant.
Checked under QEMU with -smp 24: nproc 24, /proc/cpuinfo whole.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The inode table was NINODE (200) entries, searched end to end on every
iget(), and a panic -- "iget: no inodes" -- when all of them were held.
Held means open, a cwd, a running binary or a directory mid-walk, so a
few busy processes reached it. iget() now finds an inode through a hash
on (dev, inum), takes a free one from a list, and makes more from a
slab cache once the NINODE in the image are all in use.
The open-file table had the same shape, NFILE (512) and then ENFILE,
and gets the same treatment: a free list, and the slab past NFILE.
/proc/fsstat's peaks now read against how many exist.
getrlimit(RLIMIT_NOFILE) said unlimited, which musl turns into
sysconf(_SC_OPEN_MAX) == -1, after which zsh believed it had no
descriptors and `exec {fd}<file` failed on the first one. It reports
NOFILE now. And a comment in sys_fs.c held a "*/" that ended it early.
Checked under QEMU: six processes holding 115 files each, 713 open
descriptions and 341 inodes at once, all back to the baseline after.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
The cache was NBUF buffers, 1 MB, on every machine: enough for one with
tens of megabytes and nothing on one with gigabytes, which re-read the
same directory and binary blocks off the disk for every command. It
still starts as those 256 in the kernel image, and a miss with every
buffer busy now makes a new one rather than evicting, up to 1/32 of RAM
or 256 MB. Growing on demand means nothing is spent that is not used,
and binit() needs nothing from the page allocator.
Lookups go through a hash on (dev, blockno) instead of walking the LRU
list, and bflush() walks a creation-order list with an unlocked filter
first, so neither costs more at 65536 buffers than it did at 256.
struct buf's data is a pointer to its own page now; the drivers copy
through their own DMA buffers, so where it sits does not matter.
On a 2 GB QEMU guest: a 40 MB file read back in 0.89 s instead of 1.83,
the big binaries in 0.17 s instead of 0.26. /proc/fsstat shows the
cache as buf_cached now / most.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
exec took 32 arguments and 64 environment variables, in fixed arrays,
so a glob over more than 31 files failed with E2BIG. It now reads the
caller's argv and envp where they are, through the uaccess helpers and
a bounce page -- a second thread rewriting the array after a check
cannot slip a kernel address in -- and sizes the new stack to fit
them. The limits are Linux's: ARG_MAX, 2 MB of strings and pointers,
and 128 KB for any one string (USER_STR_MAX follows it).
Every mmap took one of a process's 256 VMA slots, and zsh takes one per
16 KB heap block, so `x=($(<file))` over 30000 words ran out after 4 MB
of heap and exited 1 without a word. Neighbouring anonymous mappings
now share a record, as Linux merges them -- the bump allocator puts
each new one where the last ended -- and munmap trims or splits it.
Partial unmaps of device or segment mappings are refused with EINVAL
instead of kfree()ing pages that are not the process's, and a failed
allocation half way through a mapping no longer leaks what it had.
Checked under QEMU: touch over 3000 names, /bin/echo with 50000
arguments, E2BIG past 2 MB, zsh splitting 100000 words, fork loops.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
hwreport writes one folder to the first read-write FAT mount, or mounts
the first USB stick that takes vfat itself and unmounts it afterwards:
summary.txt (machine, firmware, CPU, memory, every PCI and USB device
with its driver or "-- no driver"), dmesg.txt, lspci.txt in the shape of
lspci -nnk -xxx, lsusb.txt, dmi.txt, memmap.txt, the ACPI tables as raw
.dat files iasl -d reads, and copies of /proc. Serials, the UUID and the
MSDM/SLIC tables (a Windows licence key) are left out.
It reads /sys, which is new: sysfs at Linux's paths and in Linux's
formats -- /sys/bus/pci/devices with uevent, config and resource,
/sys/bus/usb/devices, /sys/firmware/acpi/tables, dmi/tables, memmap
and efi, /sys/class/dmi/id. toybox's lspci and lsusb work unmodified
against it. The USB core now keeps a table of attached devices for it.
The machine's name comes from SMBIOS (kernel/dev/dmi.c). The UEFI loader
hands over the entry point from the configuration table, the kernel
falls back to the 0xF0000 scan, and the log gets Linux's "DMI:" line.
Two bugs found on the way:
- The loader handed over at most 40 memory-map entries, in firmware
order. A laptop's UEFI map is 60-150 descriptors with RAM above 4 GB
listed last, so that is what was dropped. The entries now have their
own area at 0x31000 with room for 256, are sorted before merging, and
the kernel's 32 usable regions keep the largest when there are more.
- MemTotal and sysinfo's totalram were PHYSTOP, an address, which counts
the PCI hole: a 6 GB machine reported 8. Now the usable RAM, summed.
usb.ids moves to /usr/share/hwdata, where lsusb looks for it, and
pci.ids joins it (`make pci-ids`, BSD-3-Clause like usb.ids).
Checked under QEMU q35: the report written to a FAT32 stick, fsck.fat
clean, DSDT.dat disassembled by iasl on the host, lspci -k and lsusb
showing names, 6 GB of RAM seen as 6137 MB.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Transaction groups commit from a schfsd thread every 5 seconds, on sync
and fsync, on unmount and shutdown, and early when freed-but-pending
blocks crowd the free ones -- the contract ext4 and ZFS have. A crash
still lands on the last group whole, and loses at most those seconds.
Committing before every write(2) returned cost two cache flushes and an
uberblock a call: 4 KB writes go from 2.8 to 6.6 MB/s on AHCI, and from
66 KB/s to 3.9 MB/s on QEMU's IDE disk.
Filling the disk made the root volume unmountable, on the last commit
as well: a tree update that ran out of blocks halfway was published by
the next commit. 1% of the volume (1 to 64 MiB) is now a metadata
reserve, as btrfs and ZFS keep one; data stops at it with ENOSPC as a
short write, new names at half of it, and deletes may use the rest. A
write that runs out part way records what it wrote in the inode rather
than leaving blocks past an end of file nothing moved.
Deleting a large file goes in 4 MiB steps from the end with a commit
allowed between them, as ext4 restarts its transaction through a long
truncate. Deleting 80 MB on a full disk ran out of room halfway and
leaked the rest.
The VFS's dirunlink called the object layer's whole unlink, which freed
the object with its last name, so a file removed while open lost its
data under the reader. It removes the name only now, and the object is
freed on the last iput. An object still open when the machine went down
is found by the mount's space scan and freed, like ext4's orphan list.
The allocation bitmap has a second level of pointer pages, so the mount
ceiling is 64 TiB instead of 64 GiB, and the freed-this-group bitmap
has pages only where frees happened: a 1 TiB volume takes 32 MiB.
A freed block written after the newest snapshot is reused at once
(ZFS's birth-time rule, so bfree carries the block's generation); only
older ones are kept while a snapshot exists. Deleting one snapshot no
longer stops retaining for the others, which let their blocks be
handed out again.
Checked under QEMU: crash after sync, after 8 s and within 5 s; fill to
ENOSPC, rm, remount; unlink while open; an orphan freed at the next
mount; a 1 TiB volume. schfs-check passes, with a new test for the
snapshot rule.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
NBLKDEV was 16 for every disk and partition together, which a laptop's
NVMe drive with its eight partitions and a USB stick come close to. The
mount table held 8, SchFS 4 volumes and 4 snapshots, FAT 4 volumes.
Now 32, 32, 16, 8 and 8; the device numbers still fit between the ones
already fixed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
Every path component was copied into a DIRSIZ buffer and every path
into a MAXPATH one, so names were cut at 29 bytes and paths at 127
without an error. Two names sharing their first 29 bytes opened the
same file, on SchFS and FAT alike, though both hold 255.
VFS_NAME_MAX (255) and VFS_PATH_MAX (4096) are the limits now, and
anything longer is ENAMETOOLONG. namex_from() takes its path buffers
from kalloc(), a page each, rather than putting two of them on an 8 KB
kernel stack. The v1 format still stores DIRSIZ bytes, and refuses a
longer name instead of matching on its first 30.
Checked: 255-byte names on SchFS and FAT (fsck.fat clean, and the FAT
name answers to its uppercase form), 256 refused, a 200-byte path and a
link to it, and no pages lost over 700 lookups through links.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
