Rename Schunix to SchOS; the kernel becomes SchIFT

Removes the "-unix" element and with it any trademark exposure to The
Open Group.

The split follows the ecosystem layout: SchOS is the system, and the
kernel has its own name. Kernel-identity strings are the only places
that take SchIFT -- uname(2) sysname, /proc/version, and the two licence
sentences that say "kernel" outright. That is what every Unix does here:
`uname -s` on Linux reports the kernel, not the distribution. Everything
a user reads as the product -- panic screen, boot menu, error prefixes,
docs, LICENSE, NOTICE -- is SchOS.

schunix.img is schos.img, the logo assets and the musl TLS patch are
renamed, and __SCHUNIX__ is __SCHOS__ (the define and the patch that
consumes it moved together).

Two things the rename broke, both found by the bootcheck suite:

  - shmtest wrote "SCHUNIX-MMAP-OK" with a hardcoded length of 15 and
    compared it back by hand-counted offsets (m[3]=='U', m[14]=='K').
    The shorter marker left the write running two bytes past the literal
    and the compare reading past the data, failing a file-backed mmap
    that was working correctly. Now written and compared through one
    constant with sizeof.
  - bootcheck asserted a 31-byte file after appending to
    "hello-from-schunix"; the shorter string makes it 29.

Both are the same mistake: a string literal whose length is written out
somewhere else. Full suite green -- base, Tty, Ps, Sock, Fb, Usb, Evdev.

tools/bootcheck.ps1

@@ -1,4 +1,4 @@
-# Headless boot check: run Schunix under QEMU, type commands at the shell, and
+# Headless boot check: run SchOS under QEMU, type commands at the shell, and
 # assert on what actually comes back.
 #
 # Booting to a prompt proves nothing on its own -- a filesystem can mount and
@@ -22,7 +22,7 @@
 
 param(
     [switch]$Fb,
-    # Boot schunix.iso from an emulated optical drive with NO hard disk
+    # Boot schos.iso from an emulated optical drive with NO hard disk
     # attached, which is the only way to prove the ISO is self-contained.
     # Needs `make iso` first.
     [switch]$Iso,
@@ -54,7 +54,7 @@ param(
 
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
-$hda  = Join-Path $root 'schunix.img'
+$hda  = Join-Path $root 'schos.img'
 # The root filesystem. SchFS is the only root there is, so this is not a
 # choice -- a kernel handed anything else on device 1 panics in forkret().
 $hdb  = Join-Path $root 'build\schfs.img'
@@ -67,7 +67,7 @@ Remove-Item -Force $log -ErrorAction SilentlyContinue
 # on its own, and every one of these has broken at some point while the boot
 # still looked perfectly healthy.
 $commands = @(
-    'echo hello-from-schunix > /tmp/bc.txt'
+    'echo hello-from-schos > /tmp/bc.txt'
     'cat /tmp/bc.txt'
     'echo second-line >> /tmp/bc.txt'
     'wc -c /tmp/bc.txt'
@@ -161,7 +161,7 @@ $commands += 'echo MARKER-DONE'
 # The ISO run attaches no hard disk at all. That is the whole point: a kernel
 # that still quietly needs one would boot happily here otherwise, and only
 # fail on someone else's machine.
-$isoPath = Join-Path $root 'schunix.iso'
+$isoPath = Join-Path $root 'schos.iso'
 if ($Iso -and -not (Test-Path $isoPath)) { throw "no $isoPath -- run 'make iso' first" }
 
 $drives = if ($Iso) {
@@ -222,7 +222,7 @@ $psi.Arguments = ($drives + $usbDevices + $monitor + @(
 $psi.RedirectStandardInput = $true
 $psi.UseShellExecute       = $false
 
-$what = if ($Iso) { 'schunix.iso, no hard disk' } else { "hdb = $(Split-Path $hdb -Leaf)" }
+$what = if ($Iso) { 'schos.iso, no hard disk' } else { "hdb = $(Split-Path $hdb -Leaf)" }
 Write-Host "==> booting ($what)" -ForegroundColor Cyan
 $p = [System.Diagnostics.Process]::Start($psi)
 
@@ -372,12 +372,16 @@ function Expect($pattern, $what) {
 }
 
 Expect 'MARKER-DONE'              'shell stayed alive through every command'
-Expect 'hello-from-schunix'       'a file written on the root filesystem reads back'
+Expect 'hello-from-schos'       'a file written on the root filesystem reads back'
 Expect 'second-line'              'appending to that file works'
-# 19 bytes of "hello-from-schunix\n" plus 12 of "second-line\n". The exact
+# 17 bytes of "hello-from-schos\n" plus 12 of "second-line\n". The exact
 # number is the point: an append that silently truncated still produced a file,
 # and only the byte count said which one.
-Expect '(?m)^\s*31\s'             'append extended the file rather than replacing it'
+#
+# It follows the string above, so changing that changes this -- the SchOS
+# rename shortened "hello-from-schunix" by two characters and this check went
+# red on a filesystem that was working perfectly.
+Expect '(?m)^\s*29\s'             'append extended the file rather than replacing it'
 Expect '(?m)^copy\.txt'           'a copied file appears in a new directory'
 Expect '(?ms)copy\.txt.*rmdir'    'rmdir removed the directory without an error'
 
@@ -393,7 +397,7 @@ Expect 'vga: display controller'  'the display driver found its aperture'
 
 Expect 'schfs: mounted'       'the kernel mounted SchFS as the root filesystem'
 Expect 'init: ready'          'init came up on a SchFS root'
-Expect 'label:\s*schunix'     '/proc/schfs reports the volume label'
+Expect 'label:\s*schos'     '/proc/schfs reports the volume label'
 Expect 'root_objectid:\s*16'  '/proc/schfs reports the root object id'
 Expect 'dir\s+bin'            'the root directory really contains bin/'
 # / is the mounted volume, so mounting that same device again must be
@@ -415,7 +419,7 @@ if ($gens.Count -ge 2 -and
 }
 
 if ($Fb) {
-    Expect 'id\s+schunixfb'        'FBIOGET_FSCREENINFO identifies the device'
+    Expect 'id\s+schosfb'        'FBIOGET_FSCREENINFO identifies the device'
     # 800x600 is what boot/stage2.S asks VBE for. Asserting the numbers rather
     # than just "the ioctl returned" is the point: the old code path returned
     # success with an untouched buffer, i.e. a 0x0 screen.

tools/crashshot.ps1

@@ -1,4 +1,4 @@
-# Boot Schunix, crash it on purpose, and capture the crash screen as an image.
+# Boot SchOS, crash it on purpose, and capture the crash screen as an image.
 #
 # The crash screen is the one part of the system you cannot look at by using
 # the system, so it is the one part that quietly rots. This drives it through
@@ -21,7 +21,7 @@ param(
 
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
-$hda  = Join-Path $root 'schunix.img'
+$hda  = Join-Path $root 'schos.img'
 $hdb  = if ($SchFS) { Join-Path $root 'build\schfs.img' } else { Join-Path $root 'build\fs.img' }
 $log  = Join-Path $root 'build\crashshot.log'
 $ppm  = Join-Path $root $Out
@@ -96,7 +96,7 @@ if (Test-Path $log) {
     $text = Get-Content $log -Raw
     Write-Host "==> serial transcript" -ForegroundColor Cyan
     # Only the crash report, not the whole boot.
-    $idx = $text.IndexOf('Schunix stopped')
+    $idx = $text.IndexOf('SchOS stopped')
     if ($idx -ge 0) { Write-Host $text.Substring($idx) } else { Write-Host $text }
 }
 

tools/dispshot.ps1

@@ -1,4 +1,4 @@
-# Boot Schunix, run the display self-test, and capture the result as an image.
+# Boot SchOS, run the display self-test, and capture the result as an image.
 #
 # The display class cannot be checked without a display: the assertion is "did
 # the right pixels reach the screen", and the only instrument for that is a
@@ -26,7 +26,7 @@ param(
 
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
-$hda  = Join-Path $root 'schunix.img'
+$hda  = Join-Path $root 'schos.img'
 $hdb  = if ($SchFS) { Join-Path $root 'build\schfs.img' } else { Join-Path $root 'build\fs.img' }
 $log  = Join-Path $root 'build\crashshot.log'
 $ppm  = Join-Path $root $Out

tools/fbshot.ps1

@@ -18,7 +18,7 @@ param(
 
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
-$hda  = Join-Path $root 'schunix.img'
+$hda  = Join-Path $root 'schos.img'
 $hdb  = Join-Path $root 'build\fs.img'
 $log  = Join-Path $root 'build\fbshot.log'
 $ppm  = Join-Path $root "build\fb-$Mode.ppm"

tools/loc.ps1

@@ -1,4 +1,4 @@
-# How much of Schunix is actually Schunix.
+# How much of SchOS is actually SchOS.
 #
 # `wc -l` over the whole tree answers a question nobody asked: it counts musl,
 # toybox, mksh and a NetBSD checkout, which between them are
@@ -136,13 +136,13 @@ $fmt = @(
 )
 
 Write-Host ''
-Write-Host '  Schunix — first-party source' -ForegroundColor Cyan
+Write-Host '  SchOS — first-party source' -ForegroundColor Cyan
 Write-Host ''
 Write-Host (($results | Where-Object { $_.Files -gt 0 } | Sort-Object Lines -Descending | Format-Table $fmt -AutoSize | Out-String))
 
 # Two totals, because they answer different questions and conflating them
 # flatters the number. "The OS" is what boots and runs on the machine; docs,
-# host-side tools and the projects/ stubs are first-party but are not Schunix
+# host-side tools and the projects/ stubs are first-party but are not SchOS
 # running on hardware. Linux 0.01's 10,239 lines were kernel, headers and boot
 # -- no documentation and no build tooling -- so only the first total is a fair
 # comparison.
@@ -182,7 +182,7 @@ Write-Host ''
 # measure -- every line of every file in the tarball, comments included.
 $lin = 10239
 Write-Host ('  For scale: Linux 0.01 was {0:N0} lines (kernel, headers, boot -- the' -f $lin) -ForegroundColor DarkGray
-Write-Host ('  same things counted above as THE OS ITSELF). Schunix is {0:N1}x that.' -f ($osT / $lin)) -ForegroundColor DarkGray
+Write-Host ('  same things counted above as THE OS ITSELF). SchOS is {0:N1}x that.' -f ($osT / $lin)) -ForegroundColor DarkGray
 Write-Host ''
 
 if ($PerFile) {

tools/makeiso.ps1

@@ -1,4 +1,4 @@
-# Build a bootable Schunix ISO, ready for VMware or a real machine.
+# Build a bootable SchOS ISO, ready for VMware or a real machine.
 #
 # Wraps `make iso`, which builds the ramdisk-root variant and wraps it in an
 # El Torito image. The ramdisk root is the point: the ISO carries a complete
@@ -8,7 +8,7 @@
 #   tools\makeiso.ps1 -Run         build it, then boot it under QEMU to check
 #   tools\makeiso.ps1 -Clean       force a full rebuild first
 #
-# Afterwards the ISO is schunix.iso in the repository root; point a VM's optical
+# Afterwards the ISO is schos.iso in the repository root; point a VM's optical
 # drive at it and boot from CD.
 
 param(
@@ -88,8 +88,8 @@ if ($code -ne 0) {
     Fail "make iso returned $code"
 }
 
-$iso = Join-Path $root 'schunix.iso'
-if (-not (Test-Path $iso)) { Fail "schunix.iso was not produced" }
+$iso = Join-Path $root 'schos.iso'
+if (-not (Test-Path $iso)) { Fail "schos.iso was not produced" }
 
 # `make iso` leaves the tree holding objects compiled with -DRAMDISK_ROOT. A
 # following plain `make` would then fail to link, on a missing ramdisk symbol,
@@ -106,7 +106,7 @@ Write-Host "  New VM -> I will install the OS later -> Other / Other 64-bit"
 Write-Host "  CD/DVD -> Use ISO image file -> $iso, and tick Connect at power on"
 Write-Host "  Boot order: CD-ROM first (F2 at power on for the firmware setup)"
 Write-Host ""
-Write-Host "  Set the VM to BIOS, not UEFI. Schunix's loader is 16-bit real"
+Write-Host "  Set the VM to BIOS, not UEFI. SchOS's loader is 16-bit real"
 Write-Host "  mode and there is no EFI stub yet, so a UEFI-only VM will not boot."
 Write-Host ""
 Write-Host "  Processors: as many as you like. SMP works as of 2026-08-08;"

tools/mkiso.sh

@@ -1,15 +1,15 @@
 #!/bin/sh
-# Build a bootable Schunix ISO.
+# Build a bootable SchOS ISO.
 #
 #   tools/mkiso.sh [output.iso]
 #
 # The disc boots through El Torito's "no emulation" mode, which is the only
-# one of the three that fits how Schunix actually loads itself.
+# one of the three that fits how SchOS actually loads itself.
 #
 #   floppy emulation      caps the image at 2.88 MB; the ramdisk-root kernel
 #                         alone is bigger than that.
 #   hard disk emulation   presents the image through the BIOS's INT 13h, and
-#                         Schunix's loader does not use INT 13h -- it drives
+#                         SchOS's loader does not use INT 13h -- it drives
 #                         the IDE controller's registers directly, which
 #                         cannot reach a BIOS-emulated drive.
 #   no emulation          the BIOS loads a chosen run of sectors at 0x7C00
@@ -23,7 +23,7 @@
 #
 # STAGE2_SECTORS comes from the environment, set by the Makefile, because this
 # same number also lives in boot/bootasm.S, boot/stage2main.c and the dd offsets
-# in schunix.img's recipe. It was previously written out by hand in three
+# in schos.img's recipe. It was previously written out by hand in three
 # separate spots in this file alone, and raising it for the boot logo is what
 # turned that from a latent hazard into a broken image.
 #
@@ -34,7 +34,7 @@
 set -e
 
 BUILD=${BUILD:-build}
-OUT=${1:-schunix.iso}
+OUT=${1:-schos.iso}
 STAGE2_SECTORS=${STAGE2_SECTORS:-48}
 STAGE2_BYTES=$((STAGE2_SECTORS * 512))
 LOAD_SIZE=$((1 + STAGE2_SECTORS))
@@ -59,7 +59,7 @@ stage2_sz=$(wc -c < "$STAGE2")
 rm -rf "$STAGING"
 mkdir -p "$STAGING/boot"
 
-cat "$CDBOOT" "$STAGE2" "$KERNEL" > "$STAGING/boot/schunix.bin"
+cat "$CDBOOT" "$STAGE2" "$KERNEL" > "$STAGING/boot/schos.bin"
 
 # xorriso if it is here, mkisofs otherwise. Both accept the El Torito flags
 # below unchanged -- xorriso's -as mkisofs mode exists precisely to be
@@ -79,9 +79,9 @@ fi
 
 $MKISOFS \
     -quiet \
-    -V SCHUNIX \
-    -A "Schunix" \
-    -b boot/schunix.bin \
+    -V SCHOS \
+    -A "SchOS" \
+    -b boot/schos.bin \
     -no-emul-boot \
     -boot-load-size "$LOAD_SIZE" \
     -o "$OUT" \

tools/mklogo.py

@@ -13,7 +13,7 @@ is ink -- which lets the kernel composite it in whatever the theme's accent
 happens to be, anti-aliased, at one byte per pixel. Storing RGB would be four
 times the size and would hardcode a colour into the kernel image.
 
-    python3 tools/mklogo.py "Assets/Schunix Small Logo.png" include/logo.h 128
+    python3 tools/mklogo.py "Assets/SchOS Small Logo.png" include/logo.h 128
 """
 
 import sys, zlib, struct

tools/mkschfs.c

@@ -547,7 +547,7 @@ add_tree(uint64_t dirino, const char *hostdir)
 int
 main(int argc, char **argv)
 {
-    const char *out = NULL, *sysroot = NULL, *label = "schunix";
+    const char *out = NULL, *sysroot = NULL, *label = "schos";
     uint64_t nblocks = 6000;
 
     for (int i = 1; i < argc; i++) {

tools/mutate.sh

@@ -8,7 +8,7 @@
 # say -- would otherwise look exactly like a passing mutation test, which is
 # the same failure this script exists to catch.
 set -e
-cd /mnt/d/DEV/Schunix
+cd /mnt/d/DEV/SchOS
 
 OBJ=kernel/fs/schfs/obj.c
 OBJW=kernel/fs/schfs/objw.c

tools/qrcheck.py

@@ -126,10 +126,10 @@ alpha = lambda n: "".join(chr(65 + i % 26) for i in range(n))
 
 CASES = [
     "HELLO",
-    "SCHUNIX",
+    "SCHOS",
     "a",
     "0123456789",
-    "SCHUNIX PANIC\ntrap 14 err 4 cpu 0\nrip ffffffff80104e2a",
+    "SCHOS PANIC\ntrap 14 err 4 cpu 0\nrip ffffffff80104e2a",
     bytes(range(1, 40)).decode("latin-1"),          # non-printable payload
 ]
 # One payload that exactly fills each version, and one just under, so both the

tools/qrtest.c

@@ -297,7 +297,7 @@ main(int argc, char **argv)
 
     const char *out = argc > 1 ? argv[1] : "build/qr.png";
     const char *text = argc > 2 ? argv[2] :
-        "SCHUNIX PANIC\n"
+        "SCHOS PANIC\n"
         "build 8f2a91c4\n"
         "trap 14 err 4 cpu 0\n"
         "rip ffffffff80104e2a\n"

tools/splashshot.ps1

@@ -29,7 +29,7 @@ Remove-Item -Recurse -Force $dir -ErrorAction SilentlyContinue
 New-Item -ItemType Directory -Force $dir | Out-Null
 Remove-Item -Force $log -ErrorAction SilentlyContinue
 
-$hda = Join-Path $root 'schunix.img'
+$hda = Join-Path $root 'schos.img'
 $hdb = Join-Path $root 'build\fs.img'
 
 $monPort = 55556      # not crashshot's port, so the two can run back to back

tools/textshot.ps1

@@ -1,4 +1,4 @@
-# Boot Schunix, run the text-rendering self-test, and capture the result as an image.
+# Boot SchOS, run the text-rendering self-test, and capture the result as an image.
 #
 # The display class cannot be checked without a display: the assertion is "did
 # the right pixels reach the screen", and the only instrument for that is a
@@ -26,7 +26,7 @@ param(
 
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
-$hda  = Join-Path $root 'schunix.img'
+$hda  = Join-Path $root 'schos.img'
 $hdb  = if ($SchFS) { Join-Path $root 'build\schfs.img' } else { Join-Path $root 'build\fs.img' }
 $log  = Join-Path $root 'build\crashshot.log'
 $ppm  = Join-Path $root $Out

tools/ttyshot.ps1

@@ -17,7 +17,7 @@ param(
 
 $ErrorActionPreference = 'Stop'
 $root = Split-Path $PSScriptRoot -Parent
-$hda  = Join-Path $root 'schunix.img'
+$hda  = Join-Path $root 'schos.img'
 $hdb  = Join-Path $root 'build\fs.img'
 $log  = Join-Path $root 'build\ttyshot.log'
 $ppm  = Join-Path $root $Out