Clean up build process

Makefile

@@ -1,11 +1,27 @@
 BUILD_DIR=./build
+export QEMU?=qemu-system-x86_64
+
+
+.PHONY: bios
+bios: $(BUILD_DIR)/bios.bin $(BUILD_DIR)/bios.img
 
 .PHONY: clean
-
-all: $(BUILD_DIR)/bootloader.bin
-
-include make/bios
-include make/bootloader
-
 clean:
-	rm -drf $(BUILD_DIR)
+	rm -drf $(BUILD_DIR)
+	cd bootloader; cargo clean
+
+qemu: $(BUILD_DIR)/bios.img
+	$(QEMU) \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-machine q35 \
+		-net none \
+		-enable-kvm \
+		-cpu host \
+		-drive file="$<",format=raw
+
+include make/bios

make/bios

@@ -1,12 +1,56 @@
-BIOS_SRC = ./bios
-STAGE3_BIN = $(BUILD_DIR)/stage3.elf
+# Build script for BIOS (legacy) boot.
+#
+# This compiles our bootloader as a static library,
+# and wraps it in a multistage loader.
 
-$(BUILD_DIR)/bootloader.bin: $(wildcard $(BIOS_SRC)/*.asm) $(STAGE3_BIN)
+
+# Compile bootloader as library
+LIB_SRC = ./bootloader/Cargo.toml ./bootloader/Cargo.lock $(shell find ./bootloader/src -type f)
+$(BUILD_DIR)/bios.lib: $(LIB_SRC)
+	@mkdir -p $(BUILD_DIR)
+	env RUSTFLAGS="-C soft-float" \
+	cargo rustc \
+		--manifest-path="./bootloader/Cargo.toml" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target "./bootloader/targets/x86-unknown-none.json" \
+		--lib \
+		--release \
+		-- \
+		--emit link="$(CURDIR)/$@"
+
+# Link bootloader
+BIOS_LD = ./bootloader/linkers/x86-unknown-none.ld
+$(BUILD_DIR)/bios.elf: $(BUILD_DIR)/bios.lib $(BIOS_LD)
+	ld \
+		-m elf_i386 \
+		--gc-sections \
+		-z max-page-size=0x1000 \
+		-T "$(BIOS_LD)" \
+		-o "$@" \
+		"$<"
+
+	objcopy --only-keep-debug "$@" "$@.sym"
+	objcopy --strip-debug "$@"
+
+# Wrap bootloader in three-stage BIOS loader
+BIOS_SRC = ./bios
+$(BUILD_DIR)/bios.bin: $(wildcard $(BIOS_SRC)/*.asm) $(BUILD_DIR)/bios.elf
 	@mkdir -p "$(BUILD_DIR)"
 	nasm \
 		-f bin \
 		-o "$@" \
 		-l "$@.lst" \
-		-D STAGE3="$(STAGE3_BIN)" \
+		-D STAGE3="$(BUILD_DIR)/bios.elf" \
 		-i "$(BIOS_SRC)" \
-		"$(BIOS_SRC)/bootloader.asm"
+		"$(BIOS_SRC)/main.asm"
+
+# Build demo disk image
+$(BUILD_DIR)/bios.img: $(BUILD_DIR)/bios.bin
+	rm -f "$@.partial"
+	fallocate -l 256MiB "$@.partial"
+	parted -s -a minimal "$@.partial" mklabel msdos
+	parted -s -a minimal "$@.partial" mkpart primary 2MiB 100%
+	dd if="$<" of="$@.partial" bs=1 count=512 conv=notrunc
+	dd if="$<" of="$@.partial" bs=512 skip=1 seek=1 conv=notrunc
+	mv "$@.partial" "$@"

make/bootloader

@@ -1,29 +0,0 @@
-STAGE3_SRC = ./bootloader/Cargo.toml ./bootloader/Cargo.lock $(shell find ./bootloader/src -type f)
-STAGE3_LD = ./bootloader/linkers/x86-unknown-none.ld
-
-# Compile stage 3 bootloader
-$(BUILD_DIR)/stage3.lib.a: $(STAGE3_SRC)
-	@mkdir -p $(BUILD_DIR)
-	env RUSTFLAGS="-C soft-float" \
-	cargo rustc \
-		--manifest-path="./bootloader/Cargo.toml" \
-		-Z build-std=core,alloc \
-		-Z build-std-features=compiler-builtins-mem \
-		--target "./bootloader/targets/x86-unknown-none.json" \
-		--lib \
-		--release \
-		-- \
-		--emit link="$(CURDIR)/$@"
-
-# Link stage 3 bootloader
-$(BUILD_DIR)/stage3.elf: $(BUILD_DIR)/stage3.lib.a $(STAGE3_LD)
-	ld \
-		-m elf_i386 \
-		--gc-sections \
-		-z max-page-size=0x1000 \
-		-T "$(STAGE3_LD)" \
-		-o "$@" \
-		"$<"
-
-	objcopy --only-keep-debug "$@" "$@.sym"
-	objcopy --strip-debug "$@"