Make a simple PID 1 program.

Makefile

@@ -18,6 +18,13 @@ PCH_RELEASE := $(PCH_DIR_RELEASE)/pch.h.gch
 MRUBY_CFLAGS ?= -I./libs/mruby/build/host/include
 MRUBY_LIBS ?= -L./libs/mruby/build/host/lib -lmruby
 
+BUSYBOX ?= $(shell which busybox)
+
+INITRAMFS_DIR_DEBUG := $(OBJ_DIR)/initramfs-dbg
+INITRAMFS_ARCHIVE_DEBUG := $(BIN_DIR)/initramfs-dbg.cpio.gz
+INITRAMFS_DIR_RELEASE := $(OBJ_DIR)/initramfs
+INITRAMFS_ARCHIVE_RELEASE := $(BIN_DIR)/initramfs.cpio.gz
+
 CFLAGS_DEBUG :=\
 	-std=c++23 -Wall -Wextra -fno-rtti \
 	-Og -fno-inline -gsplit-dwarf -DDEBUG \
@@ -46,9 +53,31 @@ DEP_RELEASE := $(OBJ_RELEASE:.o=.d)
 
 all: release
 
-debug: $(TARGET_DEBUG)
+debug: $(INITRAMFS_ARCHIVE_DEBUG)
 
-release: $(TARGET_RELEASE)
+release: $(INITRAMFS_ARCHIVE_RELEASE)
+
+$(INITRAMFS_ARCHIVE_DEBUG): $(TARGET_DEBUG)
+	@set -eu; \
+	root="$(INITRAMFS_DIR_DEBUG)"; \
+	mkdir -p "$$root/bin" "$$root/dev"; \
+	install -m 0755 "$(TARGET_DEBUG)" "$$root/init"; \
+	install -m 0755 "$(BUSYBOX)" "$$root/bin/busybox"; \
+	ln -sfn busybox "$$root/bin/sh"; \
+	cd "$$root"; \
+	find . -print0 | cpio --null -o --format=newc | gzip -9 > "$(abspath $(INITRAMFS_ARCHIVE_DEBUG))"; \
+	echo "Initramfs generated: $(INITRAMFS_ARCHIVE_DEBUG)"
+
+$(INITRAMFS_ARCHIVE_RELEASE): $(TARGET_RELEASE)
+	@set -eu; \
+	root="$(INITRAMFS_DIR_RELEASE)"; \
+	mkdir -p "$$root/bin" "$$root/dev"; \
+	install -m 0755 "$(TARGET_RELEASE)" "$$root/init"; \
+	install -m 0755 "$(BUSYBOX)" "$$root/bin/busybox"; \
+	ln -sfn busybox "$$root/bin/sh"; \
+	cd "$$root"; \
+	find . -print0 | cpio --null -o --format=newc | gzip -9 > "$(abspath $(INITRAMFS_ARCHIVE_RELEASE))"; \
+	echo "Initramfs generated: $(INITRAMFS_ARCHIVE_RELEASE)"
 
 $(PCH_DEBUG): $(INCLUDE_DIR)/pch.h
 	@mkdir -p $(PCH_DIR_DEBUG)