1449 lines of boot/bios/, tools/sign.pl and tools/padstage2.pl, plus the
build rules, the disk image and the ISO entry that existed to carry them.
Everything since roughly 2012 boots UEFI, and CSM -- the firmware-side
BIOS emulation that lets a legacy loader run on such a machine at all --
has been going away since Intel dropped support for it in 2020. So this
is not a path being retired early; it is one whose remaining hardware is
already the exception.
The cost was never the code, it was the tax on everything near it. Stage
2 had a 65-sector ceiling it overflowed silently -- 25440 bytes against
24576 -- and because the kernel is written at sector 1 + STAGE2_SECTORS,
an overflowing loader was overwritten by the very kernel it was loading.
The resolution list could not be shared with UEFI either: VBE mode
setting is INT 10h, so matching it needed unreal mode, which is the
riskiest code in the tree for a feature that already worked elsewhere.
What replaces schos.img is the staged ESP, handed to QEMU as a virtual
FAT volume. That is a development arrangement and not an installable
disk; a real GPT image with a real FAT partition is the installer's job,
and until it exists nothing here writes a disk a machine boots unaided.
Secure Boot is untouched too -- the loader is unsigned.
The ISO keeps one El Torito entry, the FAT image holding loader and
kernel. It never booted from a USB stick via BIOS anyway: the firmware
presents the stick as a hard disk while stage2main.c read the kernel back
over ATAPI.
The 32-bit multiboot entry in entry.S now has no caller and is left in
place. Deleting kernel entry code is its own change with its own way of
failing silently, and it should not ride along with this one.
Ported with it: run.ps1, the six screenshot tools, and schcom_test.sh,
each with its own OVMF varstore copy so no run inherits another's UEFI
variables.
Two things this shook out. OVMF now belongs in `all`: nothing boots
without firmware, `make clean` wipes build/ including the copy fetched
from the host, and a clean followed by a build left every run script
throwing. And it cannot be listed as a prerequisite at the top of the
file -- make expands prerequisites when it reads the line, and
$(OVMF_CODE) is defined further down, so naming it there appends nothing
and says nothing.
Verified from a clean tree: 110 [ok] and no failures on the full suite,
the ISO boots with no hard disk attached, schfs-check passes, schcom's
end-to-end pixel test passes, and fbshot captures a real 1280x800 frame.
boot/bios/ now holds the MBR, the El Torito stub and the real-mode stage
2; boot/uefi/ is empty and documented.
Separate directories rather than #ifdefs, because the two share almost
nothing. A BIOS loader lives in 16-bit real mode, reaches the firmware
through software interrupts, and walks itself up into long mode. A UEFI
loader is a 64-bit PE that the firmware has already placed in long mode
with paging on, calling services through a table of function pointers.
What they do share is the hand-off contract, which boot/README.md now
writes down: ELF segments placed, long mode, a 24-byte-entry memory map
at E820_MAP_ADDR, framebuffer geometry at VBE_INFO_ADDR.
That contract is the point of documenting it now. UEFI's GetMemoryMap
returns EFI_MEMORY_DESCRIPTORs, and the right move is to translate them
into the entries kernel/arch/x86_64/e820.c already parses rather than
teach the kernel a second format.
Build output paths under $(BUILD)/boot are unchanged; only sources moved.
tools/windows/ .ps1 (pwsh, so usable from Linux and macOS too)
tools/posix/ .sh
tools/python/ .py
tools/ .c and .pl
The .c and .pl files stay at the top level because they are not
host-specific: the build compiles or invokes them on every platform.
Call sites updated in the Makefile, ports/mk/port.mk, docs and the
project memory. The one thing that does not survive a move on its own is
a script deriving the repo root from its own location -- all nine
PowerShell tools used Split-Path $PSScriptRoot -Parent, and memory-sync.sh
used dirname/.., both of which quietly become tools/ one level deeper.
Two levels now.
Two pre-existing Windows failures surfaced while verifying, both real and
neither caused by the move:
- schfs_fsck.c did not compile under mingw at all: --extract uses
POSIX mkdir(path,mode), symlink() and link(), none of which mingw
has. That took the whole tool with it, and `make schfs-check` with
it. mkdir maps to _mkdir; symlink and link fail loudly rather than
writing a regular file in their place, because an extracted tree
that differs from the image while reporting success defeats the
point of --extract.
- the round-trip test then failed at `ln -s`, since Git Bash cannot
create symlinks without developer mode. It skips with a message now.
Not a fudge: mkschfs's mingw build cannot see a symlink either, so
the test would have compared a tree with none against an image with
none and called it a pass -- coverage reporting itself as present
while being absent.
Verified on Windows: build clean, all seven bootcheck suites green,
make schfs-check passes.
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.
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.
