BUILD   = build
SYSROOT = sysroot

# -----------------------------------------------------------------------
# Parallelism
#
# Nothing here is order-dependent beyond what the rules already declare, so
# there is no reason to compile one file at a time. Override with `make -j1`
# when you want readable output from a failing build.
# -----------------------------------------------------------------------
# nproc is coreutils, so it exists on Linux and under Git Bash but not on
# macOS or the BSDs, where the same number comes from sysctl. Falling through
# to 4 is a working build either way, just a slower one.
NPROC     := $(shell nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || echo 4)
MAKEFLAGS += -j$(NPROC)

# Kernel object files — organized by subsystem
KERN_ARCH = $(addprefix $(BUILD)/kernel/arch/x86_64/, \
              acpi.o e820.o entry.o trapasm.o swtch.o \
              trap.o vm.o lapic.o ioapic.o mp.o)

KERN_CORE = $(addprefix $(BUILD)/kernel/core/, \
              main.o kalloc.o dma.o spinlock.o sleeplock.o string.o console.o \
              panic.o uaccess.o qr.o time.o)

KERN_DEV  = $(addprefix $(BUILD)/kernel/dev/, \
              bio.o cdev.o device.o fb.o ide.o input.o irq.o kbd.o mouse.o \
              pci.o text.o ttf.o uart.o vga.o ramdisk.o procfs.o)

# Drivers for hardware that has to be *found* rather than assumed. Anything
# discovered by walking a bus belongs here; the fixed-address legacy devices
# (console, keyboard, PIT, the IDE ports) stay in dev/.
#
# drivers/<class>/<driver>/ -- one directory per driver, so a driver that grows
# a register header, a second source file or a firmware blob has somewhere to
# put it. Classes match include/device.h's DEVCLASS_*. Everything flat was
# already eight files with four called usb_something, and each driver added made
# the directory harder to read. The compile rule uses `mkdir -p $(dir $@)`, so
# the depth costs nothing.
KERN_DRIVERS  = $(BUILD)/kernel/drivers/registry.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/gpu/vga/vga_pci.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/gpu/virtio_gpu/virtio_gpu.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/net/e1000/e1000.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/bus/xhci/xhci.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/usb/core/usb.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/usb/hid/usb_hid.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/usb/storage/usb_storage.o
KERN_DRIVERS += $(BUILD)/kernel/drivers/usb/hub/usb_hub.o

KERN_FS   = $(addprefix $(BUILD)/kernel/fs/, \
              exec.o file.o fs.o log.o pipe.o procfs.o)

# SchFS. Every one of these is the very same source the host tools compile, so
# the kernel and mkschfs cannot disagree about the on-disk format: there is one
# implementation, found and fixed on the host where a test takes a second.
KERN_FS  += $(addprefix $(BUILD)/kernel/fs/schfs/, \
              btree.o space.o vol.o obj.o objw.o kmount.o vfs.o)

# Sockets. Unix domain only for now; an IP stack becomes more files here
# rather than a reshaping of what is already written.
KERN_NET  = $(addprefix $(BUILD)/kernel/net/, \
              unix.o)

KERN_PROC = $(addprefix $(BUILD)/kernel/proc/, \
              proc.o)

KERN_SYS  = $(addprefix $(BUILD)/kernel/sys/, \
              syscall.o sys_proc.o sys_fs.o sys_mem.o sys_net.o \
              sys_time.o sys_sig.o sys_compat.o sys_poll.o linux_abi.o)

# vectors.o lives alongside trapasm in the arch dir
KERN_ARCH += $(BUILD)/kernel/arch/x86_64/vectors.o

KERNOBJS = $(KERN_ARCH) $(KERN_CORE) $(KERN_DEV) $(KERN_DRIVERS) \
           $(KERN_FS) $(KERN_NET) $(KERN_PROC) $(KERN_SYS)
# entry.o must be first in link order; remove it from KERNOBJS for the rule
KERN_NOENTRY = $(filter-out $(BUILD)/kernel/arch/x86_64/entry.o, $(KERNOBJS))

# -----------------------------------------------------------------------
# First-party userland
#
#   lib/   startup glue + syscall stubs every cmd/ program links against
#   cmd/   one directory per program: cmd/<name>/main.c -> sysroot/bin/<name>
#
# To add a program: mkdir cmd/foo, write cmd/foo/main.c, add "foo" to CMDS.
# Third-party software does NOT go here — see ports/.
# -----------------------------------------------------------------------
ULIB    = $(addprefix $(BUILD)/lib/, start.o glue.o usys.o)
CMDS    = init schinit fbinfo shmtest socktest inputtest
CMDBINS = $(addprefix $(BUILD)/cmd/, $(CMDS))

# -----------------------------------------------------------------------
# Toolchain
# -----------------------------------------------------------------------
UNAME_S := $(shell uname -s)
UNAME_P := $(shell uname -p)

# Host platform.
#
#   WINHOST   Windows, under Git Bash or MSYS2
#   MACHOST   macOS
#   BSDHOST   FreeBSD / OpenBSD / NetBSD / DragonFly
#   (else)    Linux
#
# All four are supported hosts: this is developed from both Windows and Linux,
# and nothing here should care which.
#
# Building natively on Windows rather than in WSL, because WSL2 is a real Linux
# kernel in a Hyper-V VM and so hard-requires virtualisation; turning that on
# puts the Hyper-V hypervisor underneath the whole machine and demotes VMware
# to running nested on top of it, which is a real and permanent cost to pay for
# a build environment.
ifneq (,$(filter MINGW% MSYS% CYGWIN%,$(UNAME_S)))
  WINHOST := 1
endif
ifeq ($(UNAME_S),Darwin)
  MACHOST := 1
endif
ifneq (,$(filter FreeBSD OpenBSD NetBSD DragonFly,$(UNAME_S)))
  BSDHOST := 1
endif

QEMU    = qemu-system-x86_64

# Display for every QEMU target.
#
# virtio-gpu is what the display class binds, and what a compositor should be
# developed against: presenting is explicit, so the host never shows a
# half-drawn frame.
#
# stdvga stays alongside it and is not optional. The bootloader draws the splash
# through VBE in 16-bit real mode and there is no virtio path that early, so a
# machine with only virtio-gpu boots blind until the kernel is up. Both devices:
# virtio-gpu wins the display class, stdvga carries the splash and text console.
QEMU_DISPLAY = -vga std -device virtio-gpu-pci

# -----------------------------------------------------------------------
# Cross-compilation: clang everywhere it can be had
#
# The kernel, the bootloader and the ports all need a compiler targeting
# something other than the host -- bare-metal ELF, 16/32-bit code below one
# megabyte, and Linux/musl userland respectively. The traditional answer is a
# cross binutils+gcc per host, which is a day of work per platform that then
# rots, and on macOS means brewing x86_64-elf-* before anything builds at all.
#
# clang needs none of it: it is a cross-compiler by construction, so one
# ordinary LLVM install produces every target from every host. That was already
# how the Windows build worked; using it on all four hosts collapses what used
# to be two divergent toolchain branches -- one of which had drifted into
# passing GNU-ld-only flags to what is nowadays lld on FreeBSD and macOS -- into
# a single path that gets exercised on every platform instead of one.
#
# GNU is kept as a fallback for hosts without clang, but it is the exception.
# -----------------------------------------------------------------------
HAVE_CLANG := $(shell command -v clang 2>/dev/null)
HAVE_LLD   := $(shell command -v ld.lld 2>/dev/null)

ifeq ($(origin USE_GNU), undefined)
  ifneq (,$(HAVE_CLANG))
    ifneq (,$(HAVE_LLD))
      USE_CLANG := 1
    endif
  endif
endif

ifdef USE_CLANG
  # An explicit --target is what makes clang emit ELF rather than whatever the
  # host defaults to -- COFF on Windows, Mach-O on macOS. Without it every
  # object is silently the wrong format and the first thing to complain is the
  # linker.
  CC      = clang --target=x86_64-elf
  CC32    = clang --target=i386-elf
  LD      = ld.lld
  OBJCOPY = llvm-objcopy
  OBJDUMP = llvm-objdump
  # ld.lld has no --no-warn-rwx-segments: it does not emit that warning, so
  # there is nothing to suppress and the flag is a hard error.
  LDFLAGS = -m elf_x86_64 -nostdlib
  # The bootloader, the AP trampoline, initcode and the cmd/ programs are all
  # linked at addresses below one megabyte. GNU ld places a section wherever
  # -Ttext says; lld first checks it against a default image base of 0x400000
  # and refuses, because for a hosted program that would be a bug. Saying the
  # base is zero is how you tell it this is not a hosted program.
  LD_LOWBASE = --image-base=0
  # ports/ build *Linux userland* against musl -- a third target, distinct from
  # both the kernel (bare-metal ELF) and the host tools (native).
  #
  # -nostdlib with the crt files named explicitly, because clang otherwise
  # reaches for gcc's crtbeginT.o and libgcc, which need not exist on any
  # particular host.
  MUSLPREFIX = $(abspath $(BUILD))/ports/musl/prefix
  PORTCC  = clang --target=x86_64-unknown-linux-musl -fuse-ld=lld
  PORTCRT = -nostdlib $(MUSLPREFIX)/lib/crt1.o $(MUSLPREFIX)/lib/crti.o
  PORTEND = $(MUSLPREFIX)/lib/crtn.o
else
  # GNU fallback. Needs a cross toolchain anywhere the host's own gcc does not
  # already emit x86_64 ELF -- notably macOS, where TOOLPREFIX has to name a
  # brewed x86_64-elf-gcc.
  ifdef MACHOST
    TOOLPREFIX ?= x86_64-elf-
  else ifeq ($(UNAME_P),aarch64)
    TOOLPREFIX ?= x86_64-linux-gnu-
  else
    TOOLPREFIX ?=
  endif
  CC      = $(TOOLPREFIX)gcc
  CC32    = $(CC) -m32
  LD      = $(TOOLPREFIX)ld
  OBJCOPY = $(TOOLPREFIX)objcopy
  OBJDUMP = $(TOOLPREFIX)objdump
  LDFLAGS = -m elf_x86_64 -nostdlib --no-warn-rwx-segments
  LD_LOWBASE =
  PORTCC  = $(TOOLPREFIX)gcc
  PORTCRT =
  PORTEND =
endif

# -----------------------------------------------------------------------
# Host tools: mkfs, mkschfs, the SchFS suites, qrtest. Ordinary programs for
# the machine doing the building, so they use its native compiler.
# -----------------------------------------------------------------------
HOSTCC ?= cc

ifdef WINHOST
  # mingw-w64's gcc, not clang: clang defaults to an MSVC target here, and
  # tools/mkfs.c includes <unistd.h> and <dirent.h>, which the Windows SDK
  # does not have.
  HOSTCC   = gcc
  # mingw-w64's gcc warns about things glibc's does not (notably %lld/%zu in
  # printf against msvcrt). Those warnings are about the host build only and
  # say nothing about the image, so they must not stop it.
  HOSTWARN = -Wall
  # MinGW gcc appends .exe when the -o name has no extension, so a rule whose
  # target lacks it is never considered built -- mkfs was recompiled on every
  # single invocation of make, forever, because of this.
  EXE      = .exe
  # `python3` is not on PATH from the python.org installer; `python` is.
  PYTHON   = python
else
  HOSTWARN = -Werror -Wall
  EXE      =
  PYTHON   = python3
endif

# Host tools are generated output and live under build/, per docs/layout.md.
# $(EXE) matters: MinGW appends it, and a rule whose target lacks it never
# looks satisfied.
MKFS       = $(BUILD)/tools/mkfs$(EXE)
MKSCHFS    = $(BUILD)/tools/mkschfs$(EXE)
SCHFS_TEST = $(BUILD)/tools/schfs_test$(EXE)
SCHFS_OBJT = $(BUILD)/tools/schfs_objtest$(EXE)
SCHFS_FSCK = $(BUILD)/tools/schfs_fsck$(EXE)

OPT    ?= -O0
# -ftls-model=local-exec: the kernel is *the* executable, never a shared
# object, so its __thread variables (cpu, proc) are always at a fixed negative
# offset from the thread pointer. Saying so lets the compiler emit a direct
# `movq %rcx, %fs:-0x10` and never materialise the thread pointer as a value.
#
# GCC picked local-exec on its own for this code; clang did not, and generated
# `movq %fs:0x0, %rax; addq $-0x10, %rax; ...` instead -- which reads the TCB
# self-pointer at %fs:0, a word this kernel does not maintain and something
# else has apparently always been scribbling on. Harmless for fifteen years
# because nothing ever read it; instant triple fault the moment a compiler did.
XFLAGS  = -m64 -DX64 -mcmodel=large -mtls-direct-seg-refs -mno-red-zone
XFLAGS += -ftls-model=local-exec

# Probed once, with :=, not on every expansion of CFLAGS. CFLAGS is a
# recursively-expanded variable, so a $(shell) appended to it re-ran the probe
# on every single compile -- one extra gcc process per object file, for an
# answer that cannot change during a build.
NO_SSP := $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)

CFLAGS  = -fno-pic -static -fno-builtin -fno-strict-aliasing -Wall -MD -ggdb -fno-omit-frame-pointer
CFLAGS += -ffreestanding -fno-common -nostdlib -I./include $(XFLAGS) $(OPT)
CFLAGS += $(NO_SSP) $(CFLAGS_EXTRA)

# sys/ also needs to find table.inc via a relative include
CFLAGS_SYS = $(CFLAGS) -I./kernel/sys



# -----------------------------------------------------------------------
# Ramdisk root (opt-in):  make RAMROOT=1
#
# Links a complete SCHFS image into the kernel and boots from it instead of
# the IDE disk, so the physical disk can be reformatted from a running system.
# Off by default because it adds RAMDISK_BLOCKS KB to the kernel, and stage2
# loads the kernel by PIO one sector at a time -- a 6 MB kernel takes visibly
# longer to boot than a 350 KB one.
# -----------------------------------------------------------------------
RAMDISK_BLOCKS ?= 6000

# RAMDISK_NINODES used to live here, sizing mkfs's preallocated inode table.
# The ramdisk is a SchFS image now (see $(BUILD)/fs-ram.img) and SchFS allocates
# object ids as it goes, so there is no table to size and nothing to tune.

# Kept out of the ramdisk root.
#
# Empty right now, and the machinery is kept anyway, because this is a licensing
# rule before it is a size one: the ramdisk image is linked *into the kernel
# binary*, so anything staged in sysroot/ when it is built becomes part of a
# distributable artifact. Anything that arrives in sysroot/ under a licence that
# cannot be combined with Apache-2.0, or that simply is not ours to redistribute,
# belongs on this list rather than in someone's memory.
#
# This is not hypothetical: a 33 MB test payload once landed here and overflowed
# the 6 MB image, and mkfs's "increase FSSIZE" message then pointed at a constant
# that had nothing to do with it.
# usb.ids is 730 KB of a 6 MB image -- 12% of the ramdisk root -- and nothing
# needs it to boot. It is a lookup table for a userspace tool, so it stays on
# the disk image and out of the kernel binary.
RAMDISK_EXCLUDE = usr/share/usb.ids
RAMDISK_EXCLUDE_ARGS = $(foreach p,$(RAMDISK_EXCLUDE),--exclude $(p))

ifdef RAMROOT
CFLAGS  += -DRAMDISK_ROOT
RAMDISK_OBJ = $(BUILD)/kernel/ramdisk_obj
else
RAMDISK_OBJ =
endif

# -----------------------------------------------------------------------
# Top-level targets
# -----------------------------------------------------------------------
# usbstick.img is built here rather than on demand because bootcheck -Usb
# cannot start QEMU without it, and a missing test image looks exactly like a
# broken USB driver: QEMU refuses the -drive and the whole run produces nothing.
all: schos.img $(BUILD)/usbstick.img

schos.img: $(BUILD)/boot/bootblock $(BUILD)/boot/stage2 $(BUILD)/kernel/kernel $(BUILD)/schfs.img
	dd if=/dev/zero of=schos.img count=10000
	dd if=$(BUILD)/boot/bootblock of=schos.img conv=notrunc
	dd if=$(BUILD)/boot/stage2     of=schos.img seek=1 conv=notrunc
	# seek is 1 + STAGE2_SECTORS, not a literal. It was 25 against a 24-sector
	# stage2; raising STAGE2_SECTORS for the boot logo without touching it wrote
	# the kernel straight over stage2's own tail.
	dd if=$(BUILD)/kernel/kernel   of=schos.img seek=$$(( 1 + $(STAGE2_SECTORS) )) conv=notrunc

kernel: $(BUILD)/kernel/kernel

# -----------------------------------------------------------------------
# UEFI loader
#
# A PE/COFF executable, not ELF, so it needs a different target and a
# different linker driver -- but the same clang install. That is the whole
# reason the toolchain is clang: one compiler reaches every target here.
#
# -mno-red-zone is not optional. UEFI firmware may take an interrupt at any
# point, and the red zone is memory below RSP that a handler is entitled to
# clobber; leaving it enabled corrupts locals at random.
# -fshort-wchar makes L"..." UTF-16, which is the only string type UEFI has.
# -----------------------------------------------------------------------
UEFI_CFLAGS = --target=x86_64-unknown-windows -ffreestanding -fshort-wchar               -mno-red-zone -fno-stack-protector -Wall -Wextra -O1               -I./include

$(BUILD)/uefi/BOOTX64.EFI: boot/uefi/main.c boot/uefi/efi.h include/schboot.h
	@mkdir -p $(BUILD)/uefi
	clang $(UEFI_CFLAGS) -c boot/uefi/main.c -o $(BUILD)/uefi/main.obj
	lld-link -subsystem:efi_application -entry:EfiMain -nodefaultlib 	    $(BUILD)/uefi/main.obj -out:$@

uefi: $(BUILD)/uefi/BOOTX64.EFI

# The EFI System Partition, as a directory. QEMU serves a directory as FAT
# with `-drive file=fat:rw:`, which is enough to boot and test without any
# image-building tools -- mtools is not present on every supported host.
# A real ESP image for `make iso` is still to come.
$(BUILD)/esp/EFI/BOOT/BOOTX64.EFI: $(BUILD)/uefi/BOOTX64.EFI $(BUILD)/kernel/kernel
	@mkdir -p $(BUILD)/esp/EFI/BOOT $(BUILD)/esp/schos
	@cp $(BUILD)/uefi/BOOTX64.EFI $(BUILD)/esp/EFI/BOOT/BOOTX64.EFI
	@cp $(BUILD)/kernel/kernel $(BUILD)/esp/schos/kernel
	@cp boot/uefi/startup.nsh $(BUILD)/esp/startup.nsh
	@echo "ESP staged in $(BUILD)/esp"

esp: $(BUILD)/esp/EFI/BOOT/BOOTX64.EFI

# Boot the UEFI path under OVMF. The firmware ships with QEMU; the varstore
# is copied because it must be writable.
#
# i440fx, not q35: the kernel's IDE driver speaks to the legacy ports at
# 0x1f0, and q35 has no legacy IDE at all -- only AHCI. The root volume would
# simply not be there.
OVMF_CODE = $(BUILD)/OVMF_CODE.fd
OVMF_VARS = $(BUILD)/OVMF_VARS.fd
# OVMF, wherever this host keeps it.
#
# There is no common location: QEMU's own Windows build puts it beside the
# binary as edk2-x86_64-code.fd, Fedora ships edk2-ovmf into
# /usr/share/edk2/ovmf/OVMF_CODE.fd, Debian and Arch each differ again. Search
# rather than assume, and say something useful when nothing is found -- an
# unhelpful "cp: no such file" is a poor way to learn that a package is
# missing.
QEMU_SHARE  = $(dir $(shell command -v $(QEMU) 2>/dev/null))share
OVMF_CODE_CANDIDATES =     $(QEMU_SHARE)/edk2-x86_64-code.fd     /usr/share/edk2/ovmf/OVMF_CODE.fd     /usr/share/OVMF/OVMF_CODE.fd     /usr/share/ovmf/x64/OVMF_CODE.fd     /usr/share/qemu/edk2-x86_64-code.fd
OVMF_VARS_CANDIDATES =     $(QEMU_SHARE)/edk2-i386-vars.fd     /usr/share/edk2/ovmf/OVMF_VARS.fd     /usr/share/OVMF/OVMF_VARS.fd     /usr/share/ovmf/x64/OVMF_VARS.fd     /usr/share/qemu/edk2-i386-vars.fd

# Tested through the shell rather than with $(wildcard). On Windows, make is a
# native binary using Win32 file calls while `command -v` hands back an MSYS
# path like /c/Users/..., which $(wildcard) cannot see -- it silently returns
# nothing and the firmware looks missing on a machine that has it.
OVMF_CODE_SRC = $(shell for f in $(OVMF_CODE_CANDIDATES); do                   [ -f "$$f" ] && { echo "$$f"; break; }; done)
OVMF_VARS_SRC = $(shell for f in $(OVMF_VARS_CANDIDATES); do                   [ -f "$$f" ] && { echo "$$f"; break; }; done)

$(OVMF_CODE):
	@mkdir -p $(BUILD)
	@test -n "$(OVMF_CODE_SRC)" || { 	  echo "no OVMF firmware found. Install it:"; 	  echo "  Fedora  sudo dnf install edk2-ovmf"; 	  echo "  Debian  sudo apt install ovmf"; 	  echo "  Arch    sudo pacman -S edk2-ovmf"; 	  exit 1; }
	cp "$(OVMF_CODE_SRC)" $@
	chmod u+w $@

$(OVMF_VARS):
	@mkdir -p $(BUILD)
	@test -n "$(OVMF_VARS_SRC)" || { 	  echo "no OVMF varstore found -- install the OVMF package (see above)"; 	  exit 1; }
	cp "$(OVMF_VARS_SRC)" $@
	chmod u+w $@

qemu-uefi: esp $(BUILD)/schfs.img $(OVMF_CODE) $(OVMF_VARS)
	$(QEMU) -machine pc-i440fx-9.2 	    -drive if=pflash,format=raw,unit=0,readonly=on,file=$(OVMF_CODE) 	    -drive if=pflash,format=raw,unit=1,file=$(OVMF_VARS) 	    -drive file=fat:rw:$(BUILD)/esp,index=0,media=disk 	    -drive file=$(BUILD)/schfs.img,format=raw,index=1,media=disk 	    -m 1G -smp 1 -cpu qemu64,+rdtscp -serial mon:stdio $(QEMU_DISPLAY)

# Build the ramdisk-root variant. This is a target rather than just
# "make RAMROOT=1" because toggling RAMROOT changes CFLAGS (-DRAMDISK_ROOT),
# and make has no way to notice that: objects compiled for one setting would be
# silently reused for the other, leaving ROOTDEV pointing at the wrong device.
# Dropping the compiled objects first makes the switch always correct.
ramroot:
	rm -rf $(BUILD)/kernel $(BUILD)/lib $(BUILD)/cmd
	$(MAKE) RAMROOT=1

cmd: $(CMDBINS)

ports:
	$(MAKE) -C ports

# -----------------------------------------------------------------------
# Bootable ISO
#
# Always a ramdisk-root build. An ISO that needed a second disk to find its
# root filesystem would not be an install medium, it would be a puzzle -- and
# read-only media cannot host a writable root anyway. Same object-wiping
# preamble as the `ramroot` target, for the same reason: RAMROOT changes
# CFLAGS and make cannot see that.
# -----------------------------------------------------------------------
iso:
	rm -rf $(BUILD)/kernel $(BUILD)/lib $(BUILD)/cmd
	$(MAKE) RAMROOT=1 schos.iso

# The UEFI loader is a dependency now: the disc carries a second El Torito
# entry pointing at a FAT image that holds it, so one disc boots both firmwares.
# sysroot-install because the disc also carries the tree as a real hierarchy.
schos.iso: $(BUILD)/boot/cdboot $(BUILD)/boot/stage2 $(BUILD)/kernel/kernel \
           $(BUILD)/uefi/BOOTX64.EFI sysroot-install
	STAGE2_SECTORS=$(STAGE2_SECTORS) SYSROOT=$(SYSROOT) sh tools/posix/mkiso.sh $@

# Boot the ISO the way a machine booting off a disc would: no hard disk at
# all, so a kernel that still secretly depends on one fails here rather than
# in someone's optical drive.
qemu-iso: schos.iso
	$(QEMU) -serial mon:stdio $(QEMU_DISPLAY) -cpu qemu64,+rdtscp \
	    -cdrom schos.iso -boot d \
	    -m 1G -smp 2 -machine pc-i440fx-9.2

# -----------------------------------------------------------------------
# Bootloader — two stages. Stage 1 (bootblock) is the actual 512-byte MBR
# sector: BIOS-imposed hard limit, so it only loads stage 2 off disk and
# jumps to it. Stage 2 does VBE/A20/protected-mode setup, draws the boot
# splash, and loads the kernel — not size-constrained the same way, just
# padded out to a fixed STAGE2_SECTORS*512 bytes so the kernel's starting
# sector on disk is predictable (kept in sync with STAGE2_SECTORS in
# boot/bios/bootasm.S and boot/bios/stage2main.c).
# -----------------------------------------------------------------------
# STAGE2_SECTORS used to be written out three times -- here, in boot/bios/bootasm.S
# and in boot/bios/stage2main.c -- and docs/layout.md carried a warning about keeping
# them in step. They are now all fed from this one variable via -D, so the
# warning describes a problem that can no longer happen. Both C/asm files keep
# an #ifndef fallback purely so they still read sensibly on their own.
#
# The ceiling is memory, not disk: stage2 is loaded at 0x7E00 and the multiboot
# kernel-search buffer begins at 0x10000, so 65 sectors is the hard maximum.
# stage2main.c static-asserts this. padstage2.pl fails the build if the compiled
# binary overflows the budget, rather than truncating it -- a short stage2 would
# shift the kernel's start sector and fail in a way that looks nothing like its
# cause.
STAGE2_SECTORS = 48
STAGE2_DEF     = -DSTAGE2_SECTORS=$(STAGE2_SECTORS)
# Byte budget is computed in the recipe with shell arithmetic, not $(shell expr
# ... \* 512): make hands the backslash through untouched, sh then treats the
# `*` as a glob, and expr gets a directory listing. It "worked" to the extent
# that make carried on and padstage2.pl received nonsense.
STAGE2_BYTES   = $$(( $(STAGE2_SECTORS) * 512 ))

$(BUILD)/boot/bootblock: boot/bios/bootasm.S
	@mkdir -p $(BUILD)/boot
	$(CC32) $(STAGE2_DEF) -fno-builtin -fno-pic -nostdinc -I./include -c boot/bios/bootasm.S -o $(BUILD)/boot/bootasm.o
	$(LD) -m elf_i386 -nostdlib $(LD_LOWBASE) -n -N -e start -Ttext 0x7C00 \
	    -o $(BUILD)/boot/bootblocktmp.o $(BUILD)/boot/bootasm.o
	$(OBJCOPY) -S -O binary -j .text $(BUILD)/boot/bootblocktmp.o $(BUILD)/boot/bootblock
	./tools/sign.pl $(BUILD)/boot/bootblock

# Stage 1 for optical media. Same job as bootblock, far less of it: El Torito
# has already loaded stage2 alongside this sector by the time it runs, so it
# only records that we came from a CD and jumps. See boot/bios/cdboot.S.
$(BUILD)/boot/cdboot: boot/bios/cdboot.S
	@mkdir -p $(BUILD)/boot
	$(CC32) -fno-builtin -fno-pic -nostdinc -I./include -c boot/bios/cdboot.S -o $(BUILD)/boot/cdbootasm.o
	$(LD) -m elf_i386 -nostdlib $(LD_LOWBASE) -n -N -e start -Ttext 0x7C00 \
	    -o $(BUILD)/boot/cdboottmp.o $(BUILD)/boot/cdbootasm.o
	$(OBJCOPY) -S -O binary -j .text $(BUILD)/boot/cdboottmp.o $@
	./tools/sign.pl $@

$(BUILD)/boot/stage2: boot/bios/stage2.S boot/bios/stage2main.c include/logo.h
	@mkdir -p $(BUILD)/boot
	$(CC32) $(STAGE2_DEF) -fno-builtin -fno-pic -nostdinc -I./include -c boot/bios/stage2.S -o $(BUILD)/boot/stage2asm.o
	$(CC32) $(STAGE2_DEF) -fno-builtin -fno-pic -O -nostdinc -I./include -c boot/bios/stage2main.c -o $(BUILD)/boot/stage2main.o
	$(LD) -m elf_i386 -nostdlib $(LD_LOWBASE) -n -N -e stage2start -Ttext 0x7E00 \
	    -o $(BUILD)/boot/stage2tmp.o $(BUILD)/boot/stage2asm.o $(BUILD)/boot/stage2main.o
	$(OBJCOPY) -S -O binary -j .text -j .rodata -j .data $(BUILD)/boot/stage2tmp.o $(BUILD)/boot/stage2
	./tools/padstage2.pl $(BUILD)/boot/stage2 $(STAGE2_BYTES)

# -----------------------------------------------------------------------
# Kernel binary
# -----------------------------------------------------------------------
$(BUILD)/kernel/kernel: $(KERNOBJS) $(BUILD)/kernel/initcode_obj $(BUILD)/kernel/entryother_obj $(RAMDISK_OBJ) kernel/kernel.ld
	@mkdir -p $(BUILD)/kernel
	$(LD) $(LDFLAGS) -T kernel/kernel.ld -o $@ \
	    $(BUILD)/kernel/arch/x86_64/entry.o $(KERN_NOENTRY) \
	    $(BUILD)/kernel/initcode_obj $(BUILD)/kernel/entryother_obj $(RAMDISK_OBJ)
	$(OBJDUMP) -S $@ > $(BUILD)/kernel/kernel.asm

# The ramdisk root image, and the object wrapping it for the linker. Built from
# the same staged sysroot as the main image, just capped at RAMDISK_BLOCKS --
# mkfs's content dedup means the whole userland still fits in a few MB.
# Built with mkschfs, not mkfs.
#
# SchFS is the only root the kernel will mount -- it panics in forkret() when
# handed anything else -- so a v1 image here produced "schfs root: no SchFS
# volume on the root device" and made `make iso` and `make ramroot` unbootable.
# RAMDISK_NINODES is gone with it: SchFS has no preallocated inode table, which
# is what that knob existed to size.
$(BUILD)/fs-ram.img: $(MKSCHFS) $(BUILD)/sysroot.stamp
	@mkdir -p $(BUILD)
	@rm -f $@
	$(MKSCHFS) $@ --size $(RAMDISK_BLOCKS) --label schos \
	    $(RAMDISK_EXCLUDE_ARGS) --sysroot $(SYSROOT)

$(BUILD)/kernel/ramdisk_obj: $(BUILD)/fs-ram.img
	@mkdir -p $(BUILD)/kernel
	$(LD) -r -b binary -m elf_x86_64 -o $@ $<
	$(OBJCOPY) \
	    --redefine-sym _binary_build_fs_ram_img_start=_binary_ramdisk_start \
	    --redefine-sym _binary_build_fs_ram_img_end=_binary_ramdisk_end     \
	    --redefine-sym _binary_build_fs_ram_img_size=_binary_ramdisk_size   \
	    $@

# AP startup blob
$(BUILD)/kernel/entryother: kernel/arch/x86_64/entryother.S
	@mkdir -p $(BUILD)/kernel
	$(CC) $(CFLAGS) -fno-pic -nostdinc -I./include -c $< -o $(BUILD)/kernel/entryother.o
	$(LD) $(LDFLAGS) $(LD_LOWBASE) -e start -Ttext 0x7000 -o $(BUILD)/kernel/entryothertmp.o $(BUILD)/kernel/entryother.o
	$(OBJCOPY) -S -O binary -j .text $(BUILD)/kernel/entryothertmp.o $@

# NOTE: ld -r -b binary derives its symbol names from the *path* of the input
# file, so these --redefine-sym pairs must be kept in sync with the build
# directory layout above. Move the file, and the left-hand names change.
$(BUILD)/kernel/entryother_obj: $(BUILD)/kernel/entryother
	$(LD) -r -b binary -m elf_x86_64 -o $@ $<
	$(OBJCOPY) \
	    --redefine-sym _binary_build_kernel_entryother_start=_binary_entryother_start \
	    --redefine-sym _binary_build_kernel_entryother_end=_binary_entryother_end   \
	    --redefine-sym _binary_build_kernel_entryother_size=_binary_entryother_size  \
	    $@

# Init stub (first user-space code, embedded in the kernel image)
$(BUILD)/lib/initcode: lib/initcode.S
	@mkdir -p $(BUILD)/lib
	$(CC) $(CFLAGS) -fno-pic -nostdinc -I./include -c $< -o $(BUILD)/lib/initcode.o
	$(LD) -m elf_x86_64 -nostdlib $(LD_LOWBASE) -N -e start -Ttext 0 -o $(BUILD)/lib/initcodetmp.o $(BUILD)/lib/initcode.o
	$(OBJCOPY) -S -O binary $(BUILD)/lib/initcodetmp.o $@

$(BUILD)/kernel/initcode_obj: $(BUILD)/lib/initcode
	@mkdir -p $(BUILD)/kernel
	$(LD) -r -b binary -m elf_x86_64 -o $@ $<
	$(OBJCOPY) \
	    --redefine-sym _binary_build_lib_initcode_start=_binary_initcode_start \
	    --redefine-sym _binary_build_lib_initcode_end=_binary_initcode_end     \
	    --redefine-sym _binary_build_lib_initcode_size=_binary_initcode_size   \
	    $@

# -----------------------------------------------------------------------
# vectors.S — generated from perl script
# -----------------------------------------------------------------------
kernel/arch/x86_64/vectors.S: tools/vectors.pl
	perl tools/vectors.pl > $@

# -----------------------------------------------------------------------
# Compile rules for kernel/
# -----------------------------------------------------------------------
$(BUILD)/kernel/arch/x86_64/%.o: kernel/arch/x86_64/%.c
	@mkdir -p $(BUILD)/kernel/arch/x86_64
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/kernel/arch/x86_64/%.o: kernel/arch/x86_64/%.S
	@mkdir -p $(BUILD)/kernel/arch/x86_64
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/kernel/core/%.o: kernel/core/%.c
	@mkdir -p $(BUILD)/kernel/core
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/kernel/dev/%.o: kernel/dev/%.c
	@mkdir -p $(BUILD)/kernel/dev
	$(CC) $(CFLAGS) -c $< -o $@

# `$(dir $@)` rather than a fixed path: drivers are grouped into one directory
# per device class (gpu/, net/, bus/, usb/), so the output directory varies with
# the target and a hardcoded mkdir only creates the top one.
$(BUILD)/kernel/drivers/%.o: kernel/drivers/%.c
	@mkdir -p $(dir $@)
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/kernel/fs/%.o: kernel/fs/%.c
	@mkdir -p $(BUILD)/kernel/fs
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/kernel/fs/schfs/%.o: kernel/fs/schfs/%.c
	@mkdir -p $(BUILD)/kernel/fs/schfs
	$(CC) $(CFLAGS) -I./kernel/fs/schfs -c $< -o $@

$(BUILD)/kernel/net/%.o: kernel/net/%.c
	@mkdir -p $(BUILD)/kernel/net
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/kernel/proc/%.o: kernel/proc/%.c
	@mkdir -p $(BUILD)/kernel/proc
	$(CC) $(CFLAGS) -c $< -o $@

# sys/ gets an extra -I so syscall.c can do #include "table.inc"
$(BUILD)/kernel/sys/%.o: kernel/sys/%.c
	@mkdir -p $(BUILD)/kernel/sys
	$(CC) $(CFLAGS_SYS) -c $< -o $@

# -----------------------------------------------------------------------
# First-party userland: lib/ + cmd/
# -----------------------------------------------------------------------
$(BUILD)/lib/%.o: lib/%.c
	@mkdir -p $(BUILD)/lib
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/lib/%.o: lib/%.S
	@mkdir -p $(BUILD)/lib
	$(CC) $(CFLAGS) -c $< -o $@

$(BUILD)/cmd/%: cmd/%/main.c $(ULIB)
	@mkdir -p $(BUILD)/cmd
	$(CC) $(CFLAGS) -c $< -o $(BUILD)/cmd/$*.o
	$(LD) $(LDFLAGS) $(LD_LOWBASE) -e _start -Ttext 0x4000 -o $@ $(BUILD)/cmd/$*.o $(ULIB)
	$(OBJCOPY) -S $@

$(SYSROOT)/bin/%: $(BUILD)/cmd/% | $(SYSROOT)/bin
	cp $< $@
	chmod 755 $@

$(SYSROOT)/bin:
	mkdir -p $@

# -----------------------------------------------------------------------
# Filesystem image
# -----------------------------------------------------------------------
# -----------------------------------------------------------------------
# SchFS B-tree torture test (host program).
#
# The B-tree underpins every record type in SchFS, so it is developed and
# tested here -- against a reference model, with simulated crashes -- before
# it is linked into the kernel. Run it after any change to
# kernel/fs/schfs/btree.c.
# -----------------------------------------------------------------------
schfs-test: $(SCHFS_TEST)
	$(SCHFS_TEST)

# Use ASan/UBSan when the runtime libraries are actually installed; they catch
# exactly the pointer-arithmetic mistakes this code is most exposed to, but not
# every machine has libasan, so fall back rather than failing the build.
SAN := $(shell echo 'int main(void){return 0;}' > /tmp/.santest.c 2>/dev/null && \
         gcc -fsanitize=address,undefined -o /tmp/.santest /tmp/.santest.c \
         >/dev/null 2>&1 && echo -fsanitize=address,undefined)

SCHFS_SRC = kernel/fs/schfs/btree.c kernel/fs/schfs/btree.h \
            kernel/fs/schfs/space.c kernel/fs/schfs/vol.c \
            kernel/fs/schfs/obj.c kernel/fs/schfs/objw.c \
            kernel/fs/schfs/schfs_int.h include/schfs.h

# -iquote, not -I: include/ has its own errno.h, stat.h, fcntl.h and types.h,
# and -I would put them ahead of the system ones for a host program that needs
# the real thing. -iquote applies only to "quoted" includes, so btree.h still
# finds schfs.h while <errno.h> still means the C library's.
HOSTCFLAGS = -Wall -Wextra -O1 -g $(SAN) -iquote ./include

$(SCHFS_TEST): tools/schfs_test.c $(SCHFS_SRC)
	@mkdir -p $(BUILD)/tools
	@mkdir -p $(BUILD)
	$(HOSTCC) $(HOSTCFLAGS) -o $@ tools/schfs_test.c

# The object layer -- files, directories, and whether deleting things gives the
# space back. Runs against a memory-backed volume, so a full create/write/
# delete/remount cycle takes milliseconds instead of a rebuild and a boot.
$(SCHFS_OBJT): tools/schfs_objtest.c $(SCHFS_SRC)
	@mkdir -p $(BUILD)/tools
	@mkdir -p $(BUILD)
	$(HOSTCC) $(HOSTCFLAGS) -o $@ tools/schfs_objtest.c

schfs-objtest: $(SCHFS_OBJT)
	$(SCHFS_OBJT)

# The image writer and checker. Both #include the real filesystem sources, so
# there is exactly one implementation of the on-disk format: a host tool and the
# kernel cannot drift apart because there is nothing to drift from.
$(MKSCHFS): tools/mkschfs.c $(SCHFS_SRC)
	@mkdir -p $(BUILD)/tools
	@mkdir -p $(BUILD)
	$(HOSTCC) $(HOSTCFLAGS) -o $@ tools/mkschfs.c

$(SCHFS_FSCK): tools/schfs_fsck.c $(SCHFS_SRC)
	@mkdir -p $(BUILD)/tools
	@mkdir -p $(BUILD)
	$(HOSTCC) $(HOSTCFLAGS) -o $@ tools/schfs_fsck.c

mkschfs: $(MKSCHFS)
schfs-fsck: $(SCHFS_FSCK)

# End-to-end filesystem test: build an image from a directory tree, read it
# back with schfs_fsck, and diff the result against the original.
#
# The oracle here is the host's own filesystem, which knows nothing about SchFS.
# schfs-test proves the B-tree matches a model written alongside it; this proves
# the *filesystem* matches a tree that exists independently of it, so a writer
# and reader that agree on something wrong are still caught.
schfs-image-test: $(MKSCHFS) $(SCHFS_FSCK)
	@sh tools/posix/schfs_roundtrip.sh $(MKSCHFS) $(SCHFS_FSCK)

# Every SchFS suite. Run this after touching anything under kernel/fs/schfs.
schfs-check: schfs-test schfs-objtest schfs-image-test

# Crash the kernel on purpose and photograph the result.
#
# The crash screen is the one part of the system you cannot look at by using
# the system, which is exactly why it rots. This makes "does it still render"
# a question with a thirty-second answer. Needs a ramroot build first.
crashshot:
	pwsh -File tools/windows/crashshot.ps1

# Read the QR code back off a captured crash screen. End-to-end on purpose: it
# reads the pixels that were painted, so payload construction in panic context,
# the encoder, the module scaling and the quiet zone are all covered by whether
# text comes back. Run `make crashshot` first. Needs the same Python packages
# as `qrcheck`.
crashqr:
	$(PYTHON) tools/python/crashqr.py

$(MKFS): tools/mkfs.c include/fs.h include/stat.h include/param.h
	@mkdir -p $(BUILD)/tools
	$(HOSTCC) $(HOSTWARN) -I. -o $(MKFS) tools/mkfs.c

# Stage everything a running system needs into sysroot/, then image it.
#
# ports/ is built via its own Makefile rather than per-port from here, because
# that is where the inter-port ordering lives (mksh and toybox both link
# against musl, whose install prefix is under build/ — so `make clean` wipes it
# and musl must be rebuildable as part of the normal chain, not out-of-band).
#
# On Windows the ports are NOT rebuilt. musl, mksh and toybox are Linux
# userland built by configure scripts and kconfig, and getting those to run
# under Git Bash against a clang cross-target is a separate project from
# building the OS. Their outputs are already staged in sysroot/ and change
# perhaps twice a year, so the cost of not rebuilding them here is close to
# zero -- and it is stated out loud rather than silently skipped, because a
# port that quietly does not rebuild is exactly the kind of thing that wastes
# an afternoon later.
# schinit's job manifests. Kept under etc/ in the repo and installed here,
# because sysroot/ is generated and gitignored -- anything only ever written
# straight into it is lost on a fresh clone, which is already true of
# /etc/passwd and /etc/motd and should not become true of the boot
# configuration as well.
SCHINIT_JOBS = $(wildcard etc/schinit/*.job) etc/schinit/README
ETC_FILES    = $(wildcard etc/*)
ETC_PLAIN    = $(filter-out etc/schinit,$(ETC_FILES))

etc-install: $(SCHINIT_JOBS) $(ETC_PLAIN)
	@mkdir -p $(SYSROOT)/etc/schinit
	@cp $(ETC_PLAIN) $(SYSROOT)/etc/
	@cp $(SCHINIT_JOBS) $(SYSROOT)/etc/schinit/
	@echo "installed $(words $(ETC_PLAIN)) /etc file(s) and $(words $(SCHINIT_JOBS)) schinit manifest(s)"

sysroot-install: $(addprefix $(SYSROOT)/bin/, $(CMDS)) etc-install
ifdef WINHOST
	@echo "ports: skipped (Windows host) -- musl/mksh/toybox are used as already staged in $(SYSROOT)"
	@test -f $(SYSROOT)/bin/sh || { echo "ports: $(SYSROOT)/bin/sh is missing and cannot be built here; build ports on a Linux host once" >&2; exit 1; }
else
	$(MAKE) -C ports CC=gcc
endif

# A stamp whose timestamp advances only when the staged tree actually changes.
#
# make cannot depend on "the contents of a directory", and sysroot/ is filled
# by two different builds (cmd/ from here, ports/ recursively), so the images
# below used to depend on the phony sysroot-install -- which meant every image
# was rebuilt on every invocation, whether or not a single byte had moved.
# That cost 100 seconds of a 108-second no-op build.
#
# Path, size and mtime rather than content hashes: reading every staged file
# would undo the point, and a build system that lies about a file whose mtime
# and size both stayed the same has bigger problems. The cmp-then-move keeps
# the stamp's mtime unchanged when the summary is unchanged, which is the
# whole trick -- writing it unconditionally would just move the problem.
$(BUILD)/sysroot.stamp: sysroot-install
	@mkdir -p $(BUILD)
	@find $(SYSROOT) -type f -printf '%p %s %T@\n' | sort > $@.new
	@cmp -s $@.new $@ || mv -f $@.new $@
	@rm -f $@.new

# A small block device for the USB test to read.
#
# bootcheck -Usb attaches this as a usb-storage device and has the driver read
# block 1 off it, which is the only check that separates "a device answered
# INQUIRY" from "the driver can actually transfer data".
#
# Its own image, not the root volume and not build/fs.img:
#   - attaching the root volume twice (once as hdb, once over USB) broke the
#     xHCI interrupt check as well as the storage ones;
#   - build/fs.img is no longer built by anything, since SchFS became the root,
#     so pointing at it meant QEMU refused to start at all;
#   - at FSSIZE blocks it would now be ~600 MB, because BSIZE went from 1024 to
#     4096. 16 MB is plenty to read one block from.
USBSTICK = $(BUILD)/usbstick.img
$(USBSTICK): $(MKFS) $(BUILD)/sysroot.stamp
	@mkdir -p $(BUILD)
	@rm -f $@
	$(MKFS) $@ --size 4096 --sysroot $(SYSROOT)

usbstick: $(USBSTICK)

$(BUILD)/fs.img: $(MKFS) $(BUILD)/sysroot.stamp
	@mkdir -p $(BUILD)
	@echo "Creating SchOS File System Image..."
	@# A running QEMU holds this file open, and on Windows that makes rm fail
	@# with "Device or resource busy" -- which stops the build *after* the
	@# kernel has already relinked, leaving schos.img stale. The next test run
	@# then boots the previous kernel and the change appears to have done
	@# nothing, which has cost several debugging cycles. Say so plainly.
	@rm -f $@ || { \
	  echo ""; \
	  echo "  $@ is in use -- a QEMU is still holding it."; \
	  echo "  Close it, or: pwsh -Command \"Get-Process qemu-system-x86_64 |"; \
	  echo "                 Where-Object { -not \$$_.MainWindowTitle } | Stop-Process -Force\""; \
	  echo ""; \
	  exit 1; \
	}
	$(MKFS) $@ --sysroot $(SYSROOT)

# -----------------------------------------------------------------------
# QEMU
# -----------------------------------------------------------------------
qemu: schos.img $(BUILD)/schfs.img
	$(QEMU) -serial mon:stdio $(QEMU_DISPLAY) -cpu qemu64,+rdtscp \
	    -hda schos.img -hdb $(BUILD)/schfs.img \
	    -m 1G -smp 2 -machine pc-i440fx-9.2

# The root filesystem. Built from the staged sysroot; the kernel mounts it as
# / in forkret().
$(BUILD)/schfs.img: $(MKSCHFS) $(BUILD)/sysroot.stamp
	@mkdir -p $(BUILD)
	@rm -f $@
	./$(MKSCHFS) $@ --size 8000 --label schos --sysroot $(SYSROOT)

# Boot with a SchFS volume attached as the second disk.
#
# Needs the ramdisk-root kernel ("make ramroot" first): with RAMROOT the root
# filesystem comes out of memory and device 1 is free, which is exactly the
# arrangement docs/architecture/schfs.md asks for -- a new-format disk that
# fails to mount cannot stop the system booting. Without RAMROOT, device 1 is
# the live v1 root and the SchFS probe correctly finds nothing there.
#
# Once up:  cat /proc/schfs
qemu-schfs: schos.img $(BUILD)/schfs.img
	$(QEMU) -serial mon:stdio $(QEMU_DISPLAY) -cpu qemu64,+rdtscp \
	    -hda schos.img -hdb $(BUILD)/schfs.img \
	    -m 1G -smp 2 -machine pc-i440fx-9.2

# -----------------------------------------------------------------------
# Misc
# -----------------------------------------------------------------------
# schos.img is deliberately NOT here. It is a real file with real
# prerequisites; listing it as phony made make skip the timestamp check and
# re-run the four dd commands -- including zeroing five megabytes -- on every
# single invocation, including ones where nothing had changed.
# include/logo.h is generated but committed, exactly as include/font.h is: it
# derives from art that changes about never, and making it a build dependency
# would put Python on the critical path of every clean build for no benefit.
# Run this by hand after changing the art.
# The mark, not the wordmark. "SchOS Text Logo.png" is the text form and would
# be illegible scaled to LOGO_PX; the small logo this used to name is gone,
# replaced by the full logo, which is the same mark slightly redrawn.
LOGO_SRC = Assets/SchOS Full Logo.png
LOGO_PX  = 128

logo:
	$(PYTHON) tools/python/mklogo.py "$(LOGO_SRC)" include/logo.h $(LOGO_PX)

# The USB vendor/product name database, from linux-usb.org.
#
# Dual-licensed GPL-2.0-or-later **or** 3-clause BSD; SchOS takes the BSD
# option, which is what makes it usable at all. See NOTICE.
#
# Cached in dist/ and refreshed only when you ask, NOT on every build. That was
# the request, and it is the one thing here worth pushing back on: fetching on
# every compilation makes an offline build fail, makes the same source produce
# different images on different days, and puts a third-party web server on the
# critical path of `make`. dist/ exists precisely so a rebuild never needs the
# network -- see docs/layout.md. `make usb-ids` is a deliberate act; the file it
# writes is committed and dated, so what shipped is always knowable.
USB_IDS_URL = http://www.linux-usb.org/usb.ids

usb-ids:
	@echo "==> fetching $(USB_IDS_URL)"
	@curl -sfL --max-time 60 -o dist/usb.ids.new "$(USB_IDS_URL)" || \
	  { echo "   fetch failed; keeping the cached copy"; rm -f dist/usb.ids.new; exit 1; }
	@# A truncated or error-page download would otherwise silently replace a
	@# good database with rubbish. Check it looks like what it claims to be.
	@grep -q "^# Version:" dist/usb.ids.new || \
	  { echo "   that is not a usb.ids file; keeping the cached copy"; \
	    rm -f dist/usb.ids.new; exit 1; }
	@mv dist/usb.ids.new dist/usb.ids
	@cp dist/usb.ids $(SYSROOT)/usr/share/usb.ids
	@grep -m1 "^# Version:" dist/usb.ids

# Build the kernel's QR encoder on the host and check it.
#
# A QR symbol with a mistyped table entry still looks like a perfectly plausible
# grid of black squares, so the self-checks in qrtest.c cover what can be
# verified mechanically and the PNG covers the rest: point a phone at it.
QRTEST = $(BUILD)/tools/qrtest$(EXE)

$(QRTEST): tools/qrtest.c kernel/core/qr.c include/qr.h
	@mkdir -p $(BUILD)/tools
	$(HOSTCC) $(HOSTWARN) -I./include -o $@ tools/qrtest.c

qrtest: $(QRTEST)
	@mkdir -p $(BUILD)
	./$(QRTEST) $(BUILD)/qr.png

# The check that actually decides whether the encoder works: build a symbol and
# read it back with a real decoder, plus a module-for-module comparison against
# a second encoder. Needs Python packages that are not part of the build, so it
# is not wired into `make` -- install them wherever you like and point
# PYTHONPATH at it:
#
#   pip install --target build/pylibs opencv-python-headless numpy segno
#   PYTHONPATH=build/pylibs make qrcheck
qrcheck: $(QRTEST)
	$(PYTHON) tools/python/qrcheck.py

.PHONY: all kernel ramroot cmd ports sysroot-install qemu \
        schfs-test schfs-objtest schfs-image-test schfs-check mkschfs \
        schfs-fsck crashshot qemu-schfs iso qemu-iso clean distclean \
        logo qrtest qrcheck crashqr usb-ids
.PRECIOUS: $(BUILD)/%.o

# 'clean' removes generated output only. dist/ (upstream tarballs) survives,
# so a rebuild never needs the network.
clean:
	rm -rf $(BUILD) schos.img schos.iso kernel/arch/x86_64/vectors.S

distclean: clean
	rm -rf dist

# Header dependencies, from gcc -MD.
#
# This used to be a set of globs including `$(BUILD)/kernel/**/*.d`. make's
# wildcard has no recursive `**`: it behaved as a single `*` and matched
# exactly one level, so build/kernel/core/*.d was picked up while
# build/kernel/arch/x86_64/*.d and build/kernel/fs/schfs/*.d were not.
# Everything under arch/ and schfs/ therefore had NO header dependency
# tracking at all -- editing include/schfs.h or include/mmu.h left stale
# objects that linked without complaint. find actually recurses.
-include $(shell find $(BUILD) -name '*.d' 2>/dev/null)