SchOS/tools/mkiso.sh
Nexoniarz e04ca28812 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.
2026-08-09 14:09:59 +02:00

91 lines
3.6 KiB
Shell

#!/bin/sh
# 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 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
# 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
# and gets out of the way. That is this.
#
# So the layout below is deliberate: -boot-load-size is 1 + STAGE2_SECTORS,
# which makes the BIOS place both boot/cdboot and the whole of stage2 in memory
# before anything of ours runs. That puts stage2 at 0x7E00 -- byte for byte the
# arrangement bootasm.S produces on a hard disk. From there the only difference
# is that stage2main.c reads the kernel back with ATAPI instead of ATA.
#
# 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 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.
#
# NOT using -boot-info-table on purpose: it patches 56 bytes over offset 8 of
# the boot image, which is the middle of cdboot's code. stage2main.c finds
# where it was loaded from by reading the El Torito boot catalog instead.
set -e
BUILD=${BUILD:-build}
OUT=${1:-schos.iso}
STAGE2_SECTORS=${STAGE2_SECTORS:-48}
STAGE2_BYTES=$((STAGE2_SECTORS * 512))
LOAD_SIZE=$((1 + STAGE2_SECTORS))
STAGING="$BUILD/iso"
CDBOOT="$BUILD/boot/cdboot"
STAGE2="$BUILD/boot/stage2"
KERNEL="$BUILD/kernel/kernel"
for f in "$CDBOOT" "$STAGE2" "$KERNEL"; do
[ -f "$f" ] || { echo "mkiso: missing $f -- run make first" >&2; exit 1; }
done
# The three pieces must be contiguous and at these exact sizes: stage2main.c's
# readseg() finds the kernel at sector (1 + STAGE2_SECTORS) of the boot image,
# so a short stage2 would silently shift the kernel out from under it.
cdboot_sz=$(wc -c < "$CDBOOT")
stage2_sz=$(wc -c < "$STAGE2")
[ "$cdboot_sz" -eq 512 ] || { echo "mkiso: cdboot is $cdboot_sz bytes, expected 512" >&2; exit 1; }
[ "$stage2_sz" -eq "$STAGE2_BYTES" ] || { echo "mkiso: stage2 is $stage2_sz bytes, expected $STAGE2_BYTES (STAGE2_SECTORS=$STAGE2_SECTORS)" >&2; exit 1; }
rm -rf "$STAGING"
mkdir -p "$STAGING/boot"
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
# argument-compatible with it. The fallback is not academic: there is no xorriso
# package for Windows in scoop, where this is developed, but cdrtools provides
# mkisofs.exe.
if command -v xorriso >/dev/null 2>&1; then
MKISOFS="xorriso -as mkisofs"
elif command -v mkisofs >/dev/null 2>&1; then
MKISOFS="mkisofs"
else
echo "mkiso: need xorriso or mkisofs on PATH" >&2
echo " Windows: scoop install cdrtools" >&2
echo " Debian/Ubuntu: apt install xorriso" >&2
exit 1
fi
$MKISOFS \
-quiet \
-V SCHOS \
-A "SchOS" \
-b boot/schos.bin \
-no-emul-boot \
-boot-load-size "$LOAD_SIZE" \
-o "$OUT" \
"$STAGING"
echo "==> $OUT ($(wc -c < "$OUT") bytes)"
echo " qemu-system-x86_64 -cdrom $OUT -boot d"