Initial commit: Schunix as it stands before the SchOS rename

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.

ports/toybox/Makefile

@@ -0,0 +1,82 @@
+# SPDX-License-Identifier: Apache-2.0
+# toybox — 0BSD-licensed: https://landley.net/toybox/
+# Provides Schunix's core utilities (ls, cat, cp, mv, rm, mkdir, ...) as a
+# single multicall binary, installed under sysroot/bin/ once per applet name.
+#
+# mkfs (tools/mkfs.c) doesn't understand symlinks or hardlink dedup — each
+# sysroot/bin/<name> below is a real, independent copy of the same toybox
+# binary. That costs disk space per applet instead of one shared inode, but
+# needs no changes to mkfs and keeps this Makefile self-contained.
+
+include ../mk/port.mk
+
+TOYBOX_VERSION := 0.8.12
+TOYBOX_URL     := http://landley.net/toybox/downloads/toybox-$(TOYBOX_VERSION).tar.gz
+TOYBOX_SHA256  := ad88a921133ae2231d9f2df875ec0bd42af4429145caea7d7db9e02208a6fd2e
+
+TARBALL := $(DISTDIR)/toybox-$(TOYBOX_VERSION).tar.gz
+
+CFLAGS  := -static -D__SCHUNIX__ -I$(MUSL)/include -fno-stack-protector
+LDFLAGS := -static -L$(MUSL)/lib -lc
+
+# The applet list is not hard-coded any more: `toybox` with no arguments prints
+# exactly the applets the binary was built with, so the install below asks the
+# binary itself. A hand-maintained list installed 57 of the ~250 available and
+# silently drifted every time the toybox config changed.
+
+$(TARBALL): | $(DISTDIR)
+	curl -fsSL -o $@ $(TOYBOX_URL)
+	echo "$(TOYBOX_SHA256)  $@" | sha256sum -c -
+
+download: $(TARBALL)
+
+$(SRCDIR): $(TARBALL)
+	mkdir -p $(PORTDIR)
+	tar -xzf $< -C $(PORTDIR)
+	mv $(PORTDIR)/toybox-$(TOYBOX_VERSION) $@
+
+# toybox has no out-of-tree build mode, so its source is copied into $(BUILDDIR)
+# and built in place. $(SRCDIR) is an order-only prerequisite (|): the extracted
+# tarball never changes, and depending on it normally made a directory mtime
+# trigger a rebuild. The rebuild then failed anyway, because `cp -r` over a
+# populated $(BUILDDIR) hits "File exists" on kconfig's symlinks — so wipe it
+# first and always build from a clean copy.
+$(BUILDDIR)/toybox: | $(SRCDIR)
+	rm -rf $(BUILDDIR)
+	mkdir -p $(BUILDDIR)
+	cp -r $(SRCDIR)/. $(BUILDDIR)/
+	$(MAKE) -C $(BUILDDIR) defconfig
+	$(MAKE) -C $(BUILDDIR) CC="$(CC)" CFLAGS="$(CFLAGS)" LDFLAGS="$(LDFLAGS)"
+
+# Install every applet the binary provides, one name per applet.
+#
+# mkfs deduplicates by content, so all of these collapse to a single inode with
+# many hard links in the image -- the cost is one copy, not one per name. On the
+# host we try a hard link first for the same reason and fall back to a copy if
+# the filesystem will not take one (NTFS via WSL usually will).
+#
+# The work hangs off a stamp file rather than off the phony `install` target.
+# port.mk declares install .PHONY for every port, so this recipe used to run on
+# every single build -- re-creating 236 links whether or not toybox had been
+# rebuilt. That is slow on its own, and worse, it bumped the mtime of 236 files
+# in sysroot/ every time, which made the top-level build think the staged tree
+# had changed and rebuild the whole filesystem image from scratch.
+install: $(BUILDDIR)/toybox.installed
+
+$(BUILDDIR)/toybox.installed: $(BUILDDIR)/toybox | $(SYSROOT)/bin
+	cp $< $(SYSROOT)/bin/toybox
+	chmod 755 $(SYSROOT)/bin/toybox
+	@for a in $$($(BUILDDIR)/toybox); do \
+	    rm -f $(SYSROOT)/bin/"$$a"; \
+	    ln $(SYSROOT)/bin/toybox $(SYSROOT)/bin/"$$a" 2>/dev/null \
+	      || cp $< $(SYSROOT)/bin/"$$a"; \
+	done
+	@echo "toybox: installed $$($(BUILDDIR)/toybox | wc -w) applets"
+	@touch $@
+
+
+clean:
+	rm -rf $(PORTDIR)
+
+distclean: clean
+	rm -f $(TARBALL)