CLKS拆分：第一步

CMakeLists.txt

@@ -27,6 +27,20 @@ set(READELF_FOR_TARGET "llvm-readelf" CACHE STRING "readelf tool for limine conf
 
 set(QEMU_X86_64 "qemu-system-x86_64" CACHE STRING "QEMU executable")
 
+set(CLEONOS_SOURCE_DIR "${CMAKE_SOURCE_DIR}/cleonos")
+if(EXISTS "${CLEONOS_SOURCE_DIR}/CMakeLists.txt")
+    set(_cleonos_enable_default ON)
+else()
+    set(_cleonos_enable_default OFF)
+endif()
+set(CLEONOS_ENABLE ${_cleonos_enable_default} CACHE BOOL "Enable CLeonOS userland/ramdisk/iso integration")
+if(CLEONOS_ENABLE AND NOT EXISTS "${CLEONOS_SOURCE_DIR}/CMakeLists.txt")
+    cl_log_error("CLEONOS_ENABLE=ON but missing ${CLEONOS_SOURCE_DIR}/CMakeLists.txt")
+endif()
+if(NOT CLEONOS_ENABLE)
+    cl_log_warn("CLEONOS_ENABLE=OFF, running in CLKS-only build mode")
+endif()
+
 set(LIMINE_DIR "limine" CACHE STRING "Limine source directory")
 set(LIMINE_REPO "https://gh-proxy.com/https://github.com/limine-bootloader/limine.git" CACHE STRING "Limine git repository")
 set(LIMINE_REF "" CACHE STRING "Optional Limine branch or tag")
@@ -108,8 +122,10 @@ set(KERNEL_RUST_LIB "${BUILD_ROOT}/libclks_kernel_rust.a")
 resolve_tool_with_fallback(CC gcc cc clang)
 resolve_tool_with_fallback(KERNEL_CXX g++ clang++ x86_64-elf-g++)
 resolve_tool_with_fallback(LD ld.lld ld)
-resolve_tool_with_fallback(USER_CC cc gcc clang)
+if(CLEONOS_ENABLE)
-resolve_tool_with_fallback(USER_LD ld.lld ld)
+    resolve_tool_with_fallback(USER_CC cc gcc clang)
+    resolve_tool_with_fallback(USER_LD ld.lld ld)
+endif()
 resolve_tool_with_fallback(NM llvm-nm x86_64-elf-nm nm)
 resolve_tool_with_fallback(ADDR2LINE llvm-addr2line x86_64-elf-addr2line addr2line)
 resolve_tool_with_fallback(OBJCOPY_FOR_TARGET llvm-objcopy x86_64-linux-gnu-objcopy objcopy)
@@ -211,6 +227,13 @@ cl_set_bool_cache(CLEONOS_CLKS_ENABLE_SCHED_TASK_COUNT_LOG ON "Print scheduler t
 cl_set_bool_cache(CLEONOS_CLKS_ENABLE_INTERRUPT_READY_LOG ON "Print interrupt ready log after IDT/PIC init")
 cl_set_bool_cache(CLEONOS_CLKS_ENABLE_SHELL_MODE_LOG ON "Print default shell mode log during boot")
 
+if(NOT CLEONOS_ENABLE)
+    set(CLEONOS_CLKS_ENABLE_KELF OFF CACHE BOOL "Enable KELF app dispatcher" FORCE)
+    set(CLEONOS_CLKS_ENABLE_USERLAND_AUTO_EXEC OFF CACHE BOOL "Auto exec /shell/shell.elf on boot" FORCE)
+    set(CLEONOS_CLKS_ENABLE_USER_INIT_SCRIPT_PROBE OFF CACHE BOOL "Probe /shell/init.cmd during userland init" FORCE)
+    set(CLEONOS_CLKS_ENABLE_USER_SYSTEM_APP_PROBE OFF CACHE BOOL "Probe /system apps (elfrunner/memc) during userland init" FORCE)
+endif()
+
 cl_bool_to_int(CLEONOS_CLKS_ENABLE_AUDIO CLKS_CFG_AUDIO_INT)
 cl_bool_to_int(CLEONOS_CLKS_ENABLE_MOUSE CLKS_CFG_MOUSE_INT)
 cl_bool_to_int(CLEONOS_CLKS_ENABLE_DESKTOP CLKS_CFG_DESKTOP_INT)
@@ -267,7 +290,6 @@ set(CFLAGS_COMMON
     -Wextra
     -Werror
     "-I${CMAKE_SOURCE_DIR}/clks/include"
-    "-I${CMAKE_SOURCE_DIR}/common/include"
 )
 
 set(CXXFLAGS_COMMON
@@ -284,7 +306,6 @@ set(CXXFLAGS_COMMON
     -Wextra
     -Werror
     "-I${CMAKE_SOURCE_DIR}/clks/include"
-    "-I${CMAKE_SOURCE_DIR}/common/include"
 )
 
 set(ARCH_CFLAGS
@@ -361,7 +382,6 @@ set(USER_CFLAGS
     -Wextra
     -Werror
     "-I${CMAKE_SOURCE_DIR}/cleonos/c/include"
-    "-I${CMAKE_SOURCE_DIR}/common/include"
 )
 
 set(USER_CFLAGS_DOOM
@@ -377,7 +397,6 @@ set(USER_CFLAGS_DOOM
     -Wno-sign-compare
     -D_DEFAULT_SOURCE
     -D_POSIX_C_SOURCE=200809L
-    "-I${CMAKE_SOURCE_DIR}/common/include"
     "-I${CMAKE_SOURCE_DIR}/cleonos/third-party/doomgeneric/doomgeneric"
     "-include"
     "${CMAKE_SOURCE_DIR}/cleonos/c/apps/doom/doom_shim.h"
@@ -404,10 +423,13 @@ if(NOT CLKS_ARCH STREQUAL "x86_64")
 endif()
 
 include("${CMAKE_SOURCE_DIR}/clks/CMakeLists.txt")
-include("${CMAKE_SOURCE_DIR}/cleonos/CMakeLists.txt")
+if(CLEONOS_ENABLE)
+    include("${CMAKE_SOURCE_DIR}/cleonos/CMakeLists.txt")
+endif()
 
 add_custom_target(setup-tools
     COMMAND ${CMAKE_COMMAND}
+        "-DCLEONOS_ENABLE=${CLEONOS_ENABLE}"
         "-DGIT_TOOL=${GIT_TOOL}"
         "-DTAR_TOOL=${TAR}"
         "-DXORRISO_TOOL=${XORRISO}"
@@ -459,16 +481,17 @@ add_custom_command(
         -P "${CL_LOG_EMIT_SCRIPT}"
 )
 
-add_custom_target(disk-image
+if(CLEONOS_ENABLE)
+    add_custom_target(disk-image
         COMMAND ${CMAKE_COMMAND}
             "-DDISK_IMAGE=${DISK_IMAGE}"
             "-DDISK_MB=${CLEONOS_DISK_IMAGE_MB}"
             -P "${CMAKE_SOURCE_DIR}/cmake/ensure_disk_image.cmake"
         BYPRODUCTS "${DISK_IMAGE}"
         VERBATIM
-)
+    )
 
-add_custom_command(
+    add_custom_command(
         OUTPUT "${ISO_IMAGE}"
         COMMAND ${CMAKE_COMMAND} -E rm -rf "${ISO_ROOT}"
         COMMAND ${CMAKE_COMMAND} -E make_directory "${ISO_ROOT}/boot/limine" "${ISO_ROOT}/EFI/BOOT"
@@ -511,12 +534,12 @@ add_custom_command(
             -P "${CL_LOG_EMIT_SCRIPT}"
         DEPENDS "${KERNEL_ELF}" "${RAMDISK_IMAGE}" "${CMAKE_SOURCE_DIR}/configs/limine.conf"
         VERBATIM
-)
+    )
 
-add_custom_target(iso ALL DEPENDS "${ISO_IMAGE}")
+    add_custom_target(iso ALL DEPENDS "${ISO_IMAGE}")
-add_dependencies(iso setup-tools setup-limine kernel ramdisk)
+    add_dependencies(iso setup-tools setup-limine kernel ramdisk)
 
-add_custom_target(run
+    add_custom_target(run
         COMMAND ${CMAKE_COMMAND}
             "-DNO_COLOR=${NO_COLOR}"
             "-DLOG_LEVEL=STEP"
@@ -525,9 +548,9 @@ add_custom_target(run
         COMMAND ${QEMU_X86_64} -M pc -m 1024M -boot order=d -cdrom "${ISO_IMAGE}" -drive "file=${DISK_IMAGE},format=raw,if=ide,index=0,media=disk" -serial stdio
         DEPENDS iso disk-image
         USES_TERMINAL
-)
+    )
 
-add_custom_target(debug
+    add_custom_target(debug
         COMMAND ${CMAKE_COMMAND}
             "-DNO_COLOR=${NO_COLOR}"
             "-DLOG_LEVEL=STEP"
@@ -536,7 +559,10 @@ add_custom_target(debug
         COMMAND ${QEMU_X86_64} -M pc -m 1024M -boot order=d -cdrom "${ISO_IMAGE}" -drive "file=${DISK_IMAGE},format=raw,if=ide,index=0,media=disk" -serial stdio -s -S
         DEPENDS iso disk-image
         USES_TERMINAL
-)
+    )
+else()
+    add_custom_target(clks-default ALL DEPENDS kernel)
+endif()
 
 add_custom_target(clean-x86
     COMMAND ${CMAKE_COMMAND}
@@ -568,6 +594,7 @@ add_custom_target(clean-all
 
 find_package(Python3 COMPONENTS Interpreter QUIET)
 if(Python3_Interpreter_FOUND)
+    if(CLEONOS_ENABLE)
         add_custom_target(menuconfig
             COMMAND ${Python3_EXECUTABLE} "${CMAKE_SOURCE_DIR}/scripts/menuconfig.py"
             USES_TERMINAL
@@ -576,6 +603,24 @@ if(Python3_Interpreter_FOUND)
             COMMAND ${Python3_EXECUTABLE} "${CMAKE_SOURCE_DIR}/scripts/menuconfig.py" --gui
             USES_TERMINAL
         )
+    else()
+        add_custom_target(menuconfig
+            COMMAND ${Python3_EXECUTABLE} "${CMAKE_SOURCE_DIR}/scripts/menuconfig.py" --clks-only
+            USES_TERMINAL
+        )
+        add_custom_target(menuconfig-gui
+            COMMAND ${Python3_EXECUTABLE} "${CMAKE_SOURCE_DIR}/scripts/menuconfig.py" --gui --clks-only
+            USES_TERMINAL
+        )
+    endif()
+    add_custom_target(menuconfig-clks
+        COMMAND ${Python3_EXECUTABLE} "${CMAKE_SOURCE_DIR}/scripts/menuconfig.py" --clks-only
+        USES_TERMINAL
+    )
+    add_custom_target(menuconfig-gui-clks
+        COMMAND ${Python3_EXECUTABLE} "${CMAKE_SOURCE_DIR}/scripts/menuconfig.py" --gui --clks-only
+        USES_TERMINAL
+    )
 else()
     add_custom_target(menuconfig
         COMMAND ${CMAKE_COMMAND} -E echo "python3 not found; run scripts/menuconfig.py manually"
@@ -585,18 +630,45 @@ else()
         COMMAND ${CMAKE_COMMAND} -E echo "python3 not found; run scripts/menuconfig.py --gui manually"
         USES_TERMINAL
     )
+    add_custom_target(menuconfig-clks
+        COMMAND ${CMAKE_COMMAND} -E echo "python3 not found; run scripts/menuconfig.py --clks-only manually"
+        USES_TERMINAL
+    )
+    add_custom_target(menuconfig-gui-clks
+        COMMAND ${CMAKE_COMMAND} -E echo "python3 not found; run scripts/menuconfig.py --gui --clks-only manually"
+        USES_TERMINAL
+    )
 endif()
 
-add_custom_target(cleonos-help
+if(CLEONOS_ENABLE)
+    add_custom_target(cleonos-help
         COMMAND ${CMAKE_COMMAND} -E echo "CLeonOS CMake build system (x86_64 only)"
+        COMMAND ${CMAKE_COMMAND} -E echo "  CLEONOS_ENABLE=${CLEONOS_ENABLE}"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake -S . -B build-cmake"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig-gui"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig-clks"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig-gui-clks"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target setup"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target kernel"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target userapps"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target iso"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target run"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target debug"
         COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target disk-image"
-)
+    )
+else()
+    add_custom_target(cleonos-help
+        COMMAND ${CMAKE_COMMAND} -E echo "CLeonOS CMake build system (x86_64 only)"
+        COMMAND ${CMAKE_COMMAND} -E echo "  CLEONOS_ENABLE=${CLEONOS_ENABLE}"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake -S . -B build-cmake"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig-gui"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig-clks"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target menuconfig-gui-clks"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target setup"
+        COMMAND ${CMAKE_COMMAND} -E echo "  cmake --build build-cmake --target kernel"
+        COMMAND ${CMAKE_COMMAND} -E echo "  (CLKS-only mode: userapps/iso/run/debug/disk-image are disabled)"
+    )
+endif()
 

Makefile

@@ -19,6 +19,7 @@ PYTHON ?= python3
 MENUCONFIG_ARGS ?=
 MENUCONFIG_PRESET ?=
 DISK_IMAGE_MB ?=
+CLEONOS_ENABLE ?= auto
 
 ifeq ($(strip $(CMAKE_GENERATOR)),)
 GEN_ARG :=
@@ -28,6 +29,32 @@ endif
 
 CMAKE_PASSTHROUGH_ARGS :=
 MENUCONFIG_PRESET_ARG := $(if $(strip $(MENUCONFIG_PRESET)),--preset $(MENUCONFIG_PRESET),)
+CLEONOS_SOURCE_PRESENT := $(if $(wildcard cleonos/CMakeLists.txt),1,0)
+
+ifeq ($(strip $(CLEONOS_ENABLE)),auto)
+ifeq ($(CLEONOS_SOURCE_PRESENT),1)
+CLEONOS_ENABLE_EFFECTIVE := ON
+else
+CLEONOS_ENABLE_EFFECTIVE := OFF
+endif
+else
+CLEONOS_ENABLE_EFFECTIVE := $(CLEONOS_ENABLE)
+endif
+
+ifneq ($(filter 1 ON on TRUE true YES yes Y y,$(CLEONOS_ENABLE_EFFECTIVE)),)
+CLEONOS_ENABLED_BOOL := 1
+CLEONOS_MODE_LABEL := full
+else
+CLEONOS_ENABLED_BOOL := 0
+CLEONOS_MODE_LABEL := clks-only
+endif
+
+MENUCONFIG_SCOPE_ARG :=
+ifeq ($(CLEONOS_ENABLED_BOOL),0)
+MENUCONFIG_SCOPE_ARG += --clks-only
+endif
+
+CMAKE_PASSTHROUGH_ARGS += -DCLEONOS_ENABLE=$(CLEONOS_ENABLE_EFFECTIVE)
 
 ifneq ($(strip $(LIMINE_SKIP_CONFIGURE)),)
 CMAKE_PASSTHROUGH_ARGS += -DLIMINE_SKIP_CONFIGURE=$(LIMINE_SKIP_CONFIGURE)
@@ -57,38 +84,64 @@ ifneq ($(strip $(DISK_IMAGE_MB)),)
 CMAKE_PASSTHROUGH_ARGS += -DCLEONOS_DISK_IMAGE_MB=$(DISK_IMAGE_MB)
 endif
 
-.PHONY: all configure reconfigure menuconfig menuconfig-gui setup setup-tools setup-limine kernel userapps ramdisk-root ramdisk disk-image iso run debug clean clean-all help
+.PHONY: all configure reconfigure menuconfig menuconfig-gui menuconfig-clks menuconfig-gui-clks setup setup-tools setup-limine kernel userapps ramdisk-root ramdisk disk-image iso run debug clean clean-all help
 
+ifeq ($(CLEONOS_ENABLED_BOOL),1)
 all: iso
+else
+all: kernel
+endif
 
 configure:
 > @$(CMAKE) -S . -B $(CMAKE_BUILD_DIR) $(GEN_ARG) -DCMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) -DNO_COLOR=$(NO_COLOR) $(CMAKE_EXTRA_ARGS) $(CMAKE_PASSTHROUGH_ARGS)
 
 reconfigure:
 > @rm -rf $(CMAKE_BUILD_DIR)
-> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)"
+> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)" CLEONOS_ENABLE="$(CLEONOS_ENABLE)"
 
 menuconfig:
 > @if command -v $(PYTHON) >/dev/null 2>&1; then \
->     $(PYTHON) scripts/menuconfig.py $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+>     $(PYTHON) scripts/menuconfig.py $(MENUCONFIG_SCOPE_ARG) $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
 > elif command -v python >/dev/null 2>&1; then \
->     python scripts/menuconfig.py $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+>     python scripts/menuconfig.py $(MENUCONFIG_SCOPE_ARG) $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
 > else \
 >     echo "python3/python not found"; \
 >     exit 1; \
 > fi
-> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)"
+> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)" CLEONOS_ENABLE="$(CLEONOS_ENABLE)"
 
 menuconfig-gui:
 > @if command -v $(PYTHON) >/dev/null 2>&1; then \
->     $(PYTHON) scripts/menuconfig.py --gui $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+>     $(PYTHON) scripts/menuconfig.py --gui $(MENUCONFIG_SCOPE_ARG) $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
 > elif command -v python >/dev/null 2>&1; then \
->     python scripts/menuconfig.py --gui $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+>     python scripts/menuconfig.py --gui $(MENUCONFIG_SCOPE_ARG) $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
 > else \
 >     echo "python3/python not found"; \
 >     exit 1; \
 > fi
-> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)"
+> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)" CLEONOS_ENABLE="$(CLEONOS_ENABLE)"
+
+menuconfig-clks:
+> @if command -v $(PYTHON) >/dev/null 2>&1; then \
+>     $(PYTHON) scripts/menuconfig.py --clks-only $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+> elif command -v python >/dev/null 2>&1; then \
+>     python scripts/menuconfig.py --clks-only $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+> else \
+>     echo "python3/python not found"; \
+>     exit 1; \
+> fi
+> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)" CLEONOS_ENABLE="$(CLEONOS_ENABLE)"
+
+menuconfig-gui-clks:
+> @if command -v $(PYTHON) >/dev/null 2>&1; then \
+>     $(PYTHON) scripts/menuconfig.py --gui --clks-only $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+> elif command -v python >/dev/null 2>&1; then \
+>     python scripts/menuconfig.py --gui --clks-only $(MENUCONFIG_PRESET_ARG) $(MENUCONFIG_ARGS); \
+> else \
+>     echo "python3/python not found"; \
+>     exit 1; \
+> fi
+> @$(MAKE) configure CMAKE_BUILD_TYPE=$(CMAKE_BUILD_TYPE) CMAKE_GENERATOR="$(CMAKE_GENERATOR)" CMAKE_EXTRA_ARGS="$(CMAKE_EXTRA_ARGS)" NO_COLOR="$(NO_COLOR)" LIMINE_SKIP_CONFIGURE="$(LIMINE_SKIP_CONFIGURE)" LIMINE_REF="$(LIMINE_REF)" LIMINE_REPO="$(LIMINE_REPO)" LIMINE_DIR="$(LIMINE_DIR)" LIMINE_BIN_DIR="$(LIMINE_BIN_DIR)" OBJCOPY_FOR_TARGET="$(OBJCOPY_FOR_TARGET)" OBJDUMP_FOR_TARGET="$(OBJDUMP_FOR_TARGET)" READELF_FOR_TARGET="$(READELF_FOR_TARGET)" CLEONOS_ENABLE="$(CLEONOS_ENABLE)"
 
 setup: configure
 > @$(CMAKE) --build $(CMAKE_BUILD_DIR) --target setup
@@ -102,6 +155,7 @@ setup-limine: configure
 kernel: configure
 > @$(CMAKE) --build $(CMAKE_BUILD_DIR) --target kernel
 
+ifeq ($(CLEONOS_ENABLED_BOOL),1)
 userapps: configure
 > @$(CMAKE) --build $(CMAKE_BUILD_DIR) --target userapps
 
@@ -122,6 +176,11 @@ run: configure
 
 debug: configure
 > @$(CMAKE) --build $(CMAKE_BUILD_DIR) --target debug
+else
+userapps ramdisk-root ramdisk disk-image iso run debug:
+> @echo "target '$@' requires CLEONOS_ENABLE=ON and cleonos sources present"
+> @exit 1
+endif
 
 clean:
 > @if [ -d "$(CMAKE_BUILD_DIR)" ]; then \
@@ -139,9 +198,12 @@ clean-all:
 
 help:
 > @echo "CLeonOS (CMake-backed wrapper)"
+> @echo "Mode: CLEONOS_ENABLE=$(CLEONOS_ENABLE_EFFECTIVE) ($(CLEONOS_MODE_LABEL))"
 > @echo "  make configure"
 > @echo "  make menuconfig"
 > @echo "  make menuconfig-gui"
+> @echo "  make menuconfig-clks"
+> @echo "  make menuconfig-gui-clks"
 > @echo "  make setup"
 > @echo "  make userapps"
 > @echo "  make disk-image"
@@ -155,6 +217,9 @@ help:
 > @echo "  make configure CMAKE_EXTRA_ARGS='-DLIMINE_SKIP_CONFIGURE=1 -DOBJCOPY_FOR_TARGET=objcopy'"
 > @echo "Direct passthrough is also supported:"
 > @echo "  make run LIMINE_SKIP_CONFIGURE=1"
+> @echo "Kernel-only mode:"
+> @echo "  make kernel CLEONOS_ENABLE=OFF"
+> @echo "  make -C clks kernel"
 > @echo "Disk image size example:"
 > @echo "  make run DISK_IMAGE_MB=128"
 > @echo "Preset examples:"

cleonos/c/include/cleonos_version.h

@@ -1,7 +1,6 @@
 #ifndef CLEONOS_VERSION_H
 #define CLEONOS_VERSION_H
 
-#define CLKS_VERSION_STRING "1.0.0-alpha"
 #define CLEONOS_VERSION_STRING "1.0.0-alpha"
 
 #endif

clks/Makefile

@@ -0,0 +1,47 @@
+.RECIPEPREFIX := >
+MAKEFLAGS += --no-print-directory
+
+ROOT_DIR := $(abspath $(dir $(lastword $(MAKEFILE_LIST)))/..)
+
+.PHONY: all configure reconfigure kernel menuconfig menuconfig-gui setup setup-tools setup-limine clean clean-all help
+
+all: kernel
+
+configure:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF configure
+
+reconfigure:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF reconfigure
+
+kernel:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF kernel
+
+menuconfig:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF menuconfig-clks
+
+menuconfig-gui:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF menuconfig-gui-clks
+
+setup:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF setup
+
+setup-tools:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF setup-tools
+
+setup-limine:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF setup-limine
+
+clean:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF clean
+
+clean-all:
+> @$(MAKE) -C "$(ROOT_DIR)" CLEONOS_ENABLE=OFF clean-all
+
+help:
+> @echo "CLKS standalone wrapper"
+> @echo "  make -C clks kernel"
+> @echo "  make -C clks menuconfig"
+> @echo "  make -C clks menuconfig-gui"
+> @echo "  make -C clks configure"
+> @echo "  make -C clks clean"
+> @echo "  make -C clks clean-all"

clks/include/clks/version.h

@@ -0,0 +1,6 @@
+#ifndef CLKS_VERSION_H
+#define CLKS_VERSION_H
+
+#define CLKS_VERSION_STRING "1.0.0-alpha"
+
+#endif

clks/kernel/runtime/syscall.c

@@ -17,7 +17,7 @@
 #include <clks/tty.h>
 #include <clks/types.h>
 #include <clks/userland.h>
-#include <cleonos_version.h>
+#include <clks/version.h>
 
 /* Yes, this file is a syscall kitchen sink and nobody is pretending otherwise. */
 

cmake/check_tools.cmake

@@ -20,10 +20,11 @@ function(require_tool TOOL_VALUE)
 endfunction()
 
 cl_log_step("checking host tools")
+if(NOT DEFINED CLEONOS_ENABLE)
+    set(CLEONOS_ENABLE ON)
+endif()
 
 require_tool("${GIT_TOOL}")
-require_tool("${TAR_TOOL}")
-require_tool("${XORRISO_TOOL}")
 require_tool("${CC_TOOL}")
 require_tool("${LD_TOOL}")
 require_tool("${OBJCOPY_TOOL}")
@@ -31,10 +32,14 @@ require_tool("${OBJDUMP_TOOL}")
 require_tool("${READELF_TOOL}")
 require_tool("${NM_TOOL}")
 require_tool("${ADDR2LINE_TOOL}")
-require_tool("${USER_CC_TOOL}")
-require_tool("${USER_LD_TOOL}")
 require_tool("${RUSTC_TOOL}")
 require_tool("${MAKE_TOOL}")
 require_tool("${SH_TOOL}")
+if(CLEONOS_ENABLE)
+    require_tool("${TAR_TOOL}")
+    require_tool("${XORRISO_TOOL}")
+    require_tool("${USER_CC_TOOL}")
+    require_tool("${USER_LD_TOOL}")
+endif()
 
 cl_log_info("required tools are available")

scripts/menuconfig.py

@@ -5,6 +5,10 @@ CLeonOS menuconfig
 Interactive feature selector that writes:
   - configs/menuconfig/.config.json
   - configs/menuconfig/config.cmake
+  - configs/menuconfig/.config.clks.json
+  - configs/menuconfig/config.clks.cmake
+  - configs/menuconfig/.config.cleonos.json
+  - configs/menuconfig/config.cleonos.cmake
 
 Design:
   - CLKS options come from configs/menuconfig/clks_features.json
@@ -44,6 +48,10 @@ MENUCONFIG_DIR = ROOT_DIR / "configs" / "menuconfig"
 CLKS_FEATURES_PATH = MENUCONFIG_DIR / "clks_features.json"
 CONFIG_JSON_PATH = MENUCONFIG_DIR / ".config.json"
 CONFIG_CMAKE_PATH = MENUCONFIG_DIR / "config.cmake"
+CONFIG_CLKS_JSON_PATH = MENUCONFIG_DIR / ".config.clks.json"
+CONFIG_CLEONOS_JSON_PATH = MENUCONFIG_DIR / ".config.cleonos.json"
+CONFIG_CLKS_CMAKE_PATH = MENUCONFIG_DIR / "config.clks.cmake"
+CONFIG_CLEONOS_CMAKE_PATH = MENUCONFIG_DIR / "config.cleonos.cmake"
 
 
 @dataclass(frozen=True)
@@ -388,11 +396,11 @@ def discover_user_apps() -> List[OptionItem]:
     return options
 
 
-def load_previous_values() -> Dict[str, int]:
+def _load_values_from_json(path: Path) -> Dict[str, int]:
-    if not CONFIG_JSON_PATH.exists():
+    if not path.exists():
         return {}
     try:
-        raw = json.loads(CONFIG_JSON_PATH.read_text(encoding="utf-8"))
+        raw = json.loads(path.read_text(encoding="utf-8"))
     except Exception:
         return {}
 
@@ -407,6 +415,16 @@ def load_previous_values() -> Dict[str, int]:
     return out
 
 
+def load_previous_values(include_user: bool) -> Dict[str, int]:
+    out: Dict[str, int] = {}
+    # Merge order: legacy combined -> split CLKS -> split CLeonOS.
+    out.update(_load_values_from_json(CONFIG_JSON_PATH))
+    out.update(_load_values_from_json(CONFIG_CLKS_JSON_PATH))
+    if include_user:
+        out.update(_load_values_from_json(CONFIG_CLEONOS_JSON_PATH))
+    return out
+
+
 def init_values(options: Iterable[OptionItem], previous: Dict[str, int], use_defaults: bool) -> Dict[str, int]:
     values: Dict[str, int] = {}
     for item in options:
@@ -1368,12 +1386,15 @@ def _run_ncurses_main(stdscr, clks_options: List[OptionItem], user_options: List
         total_items = len(clks_options) + len(user_options)
         total_on = clks_on + user_on
 
-        items = [
+        menu_entries: List[Tuple[str, str]] = [
-            f"CLKS features ({clks_on}/{len(clks_options)} enabled)",
+            ("clks", f"CLKS features ({clks_on}/{len(clks_options)} enabled)"),
-            f"User apps ({user_on}/{len(user_options)} enabled)",
-            "Save and Exit",
-            "Quit without Saving",
         ]
+        if user_options:
+            menu_entries.append(("user", f"User apps ({user_on}/{len(user_options)} enabled)"))
+        else:
+            menu_entries.append(("user-disabled", "User apps (CLKS-only mode)"))
+        menu_entries.append(("save", "Save and Exit"))
+        menu_entries.append(("quit", "Quit without Saving"))
 
         if h < 12 or w < 58:
             _safe_addnstr(stdscr, 0, 0, "Terminal too small for menuconfig (need >= 58x12).", theme["status_warn"])
@@ -1387,7 +1408,7 @@ def _run_ncurses_main(stdscr, clks_options: List[OptionItem], user_options: List
         _draw_box(stdscr, 2, 0, h - 5, w, "Main", theme["panel_border"], theme["panel_title"])
 
         base = 4
-        for i, text in enumerate(items):
+        for i, (_action, text) in enumerate(menu_entries):
             prefix = ">" if i == selected else " "
             row_text = f"{prefix} {text}"
             attr = theme["selected"] if i == selected else theme["value_label"]
@@ -1406,7 +1427,10 @@ def _run_ncurses_main(stdscr, clks_options: List[OptionItem], user_options: List
         )
 
         _safe_addnstr(stdscr, h - 2, 0, " Arrows/jk move  Enter select  s save  q quit ", theme["help"])
+        if user_options:
             _safe_addnstr(stdscr, h - 1, 0, " Tip: open CLKS/USER section then use Space to toggle options. ", theme["help"])
+        else:
+            _safe_addnstr(stdscr, h - 1, 0, " Tip: CLKS-only mode, open CLKS section then use Space to toggle options. ", theme["help"])
         stdscr.refresh()
 
         key = stdscr.getch()
@@ -1416,20 +1440,23 @@ def _run_ncurses_main(stdscr, clks_options: List[OptionItem], user_options: List
         if key in (ord("s"), ord("S")):
             return True
         if key in (curses.KEY_UP, ord("k"), ord("K")):
-            selected = (selected - 1) % len(items)
+            selected = (selected - 1) % len(menu_entries)
             continue
         if key in (curses.KEY_DOWN, ord("j"), ord("J")):
-            selected = (selected + 1) % len(items)
+            selected = (selected + 1) % len(menu_entries)
             continue
         if key in (curses.KEY_ENTER, 10, 13):
-            if selected == 0:
+            action = menu_entries[selected][0]
+            if action == "clks":
                 _run_ncurses_grouped_section(stdscr, theme, "CLKS", clks_options, all_options, values)
-            elif selected == 1:
+            elif action == "user":
                 _run_ncurses_section(stdscr, theme, "USER", user_options, all_options, values)
-            elif selected == 2:
+            elif action == "save":
                 return True
-            else:
+            elif action == "quit":
                 return False
+            else:
+                continue
             continue
 
 
@@ -1501,7 +1528,10 @@ def interactive_menu_gui(clks_options: List[OptionItem], user_options: List[Opti
     header_title.setFont(header_font)
     root_layout.addWidget(header_title)
 
+    if user_options:
         root_layout.addWidget(QtWidgets.QLabel("Window mode (PySide): configure CLKS features and user apps, then save."))
+    else:
+        root_layout.addWidget(QtWidgets.QLabel("Window mode (PySide): CLKS-only mode (user app options unavailable)."))
 
     summary_label = QtWidgets.QLabel("")
     root_layout.addWidget(summary_label)
@@ -1743,8 +1773,9 @@ def interactive_menu_gui(clks_options: List[OptionItem], user_options: List[Opti
         for group_name, group_items in clks_groups:
             clks_tabs.addTab(_SectionPanel(f"CLKS Features / {group_name}", group_items), group_name)
 
-    user_panel = _SectionPanel("User Apps", user_options)
     tabs.addTab(clks_panel, "CLKS")
+    if user_options:
+        user_panel = _SectionPanel("User Apps", user_options)
         tabs.addTab(user_panel, "USER")
     update_summary()
 
@@ -1777,31 +1808,31 @@ def interactive_menu_gui(clks_options: List[OptionItem], user_options: List[Opti
     return result["save"]
 
 
-def write_outputs(all_values: Dict[str, int], ordered_options: List[OptionItem]) -> None:
+def _write_json_config(path: Path, values: Dict[str, int], options: List[OptionItem]) -> None:
-    MENUCONFIG_DIR.mkdir(parents=True, exist_ok=True)
-
     output_values: Dict[str, object] = {}
-    for item in ordered_options:
+    for item in options:
-        if item.key not in all_values:
+        if item.key not in values:
             continue
-        value = normalize_tri(all_values[item.key], item.default, item.kind)
+        value = normalize_tri(values[item.key], item.default, item.kind)
         if item.kind == "bool":
             output_values[item.key] = value == TRI_Y
         else:
             output_values[item.key] = tri_char(value)
 
-    CONFIG_JSON_PATH.write_text(
+    path.write_text(
         json.dumps(output_values, ensure_ascii=True, indent=2, sort_keys=True) + "\n",
         encoding="utf-8",
     )
 
+
+def _write_cmake_config(path: Path, values: Dict[str, int], options: List[OptionItem], loaded_var: str) -> None:
     lines = [
         "# Auto-generated by scripts/menuconfig.py",
         "# Do not edit manually unless you know what you are doing.",
-        'set(CLEONOS_MENUCONFIG_LOADED ON CACHE BOOL "CLeonOS menuconfig loaded" FORCE)',
+        f'set({loaded_var} ON CACHE BOOL "CLeonOS menuconfig loaded" FORCE)',
     ]
-    for item in ordered_options:
+    for item in options:
-        value = normalize_tri(all_values.get(item.key, item.default), item.default, item.kind)
+        value = normalize_tri(values.get(item.key, item.default), item.default, item.kind)
         if item.kind == "bool":
             cmake_value = "ON" if value == TRI_Y else "OFF"
             lines.append(f'set({item.key} {cmake_value} CACHE BOOL "{item.title}" FORCE)')
@@ -1813,6 +1844,39 @@ def write_outputs(all_values: Dict[str, int], ordered_options: List[OptionItem])
                 f'CACHE BOOL "{item.title} enabled(y|m)" FORCE)'
             )
 
+    path.write_text("\n".join(lines) + "\n", encoding="utf-8")
+
+
+def write_outputs(all_values: Dict[str, int], clks_options: List[OptionItem], user_options: List[OptionItem]) -> None:
+    MENUCONFIG_DIR.mkdir(parents=True, exist_ok=True)
+    ordered_options = clks_options + user_options
+
+    _write_json_config(CONFIG_JSON_PATH, all_values, ordered_options)
+    _write_json_config(CONFIG_CLKS_JSON_PATH, all_values, clks_options)
+    _write_cmake_config(CONFIG_CLKS_CMAKE_PATH, all_values, clks_options, "CLEONOS_MENUCONFIG_CLKS_LOADED")
+
+    if user_options:
+        _write_json_config(CONFIG_CLEONOS_JSON_PATH, all_values, user_options)
+        _write_cmake_config(
+            CONFIG_CLEONOS_CMAKE_PATH,
+            all_values,
+            user_options,
+            "CLEONOS_MENUCONFIG_CLEONOS_LOADED",
+        )
+    else:
+        if CONFIG_CLEONOS_JSON_PATH.exists():
+            CONFIG_CLEONOS_JSON_PATH.unlink()
+        if CONFIG_CLEONOS_CMAKE_PATH.exists():
+            CONFIG_CLEONOS_CMAKE_PATH.unlink()
+
+    # Backward-compatible aggregator for existing CMake include path.
+    lines = [
+        "# Auto-generated by scripts/menuconfig.py",
+        "# Backward-compatible aggregate include.",
+        'set(CLEONOS_MENUCONFIG_LOADED ON CACHE BOOL "CLeonOS menuconfig loaded" FORCE)',
+        'include("${CMAKE_CURRENT_LIST_DIR}/config.clks.cmake" OPTIONAL)',
+        'include("${CMAKE_CURRENT_LIST_DIR}/config.cleonos.cmake" OPTIONAL)',
+    ]
     CONFIG_CMAKE_PATH.write_text("\n".join(lines) + "\n", encoding="utf-8")
 
 
@@ -1826,22 +1890,29 @@ def show_summary(clks_options: List[OptionItem], user_options: List[OptionItem],
     print()
     print("========== CLeonOS menuconfig ==========")
     print(f"1) CLKS features : on={clks_on} m={clks_m} total={len(clks_options)}")
+    if user_options:
         print(f"2) User features : on={user_on} m={user_m} total={len(user_options)}")
+    else:
+        print("2) User features : unavailable (CLKS-only mode)")
     print("s) Save and exit")
     print("q) Quit without saving")
 
 
 def interactive_menu(clks_options: List[OptionItem], user_options: List[OptionItem], values: Dict[str, int]) -> bool:
     all_options = clks_options + user_options
+    has_user = len(user_options) > 0
     while True:
         show_summary(clks_options, user_options, values)
         choice = input("Select> ").strip().lower()
         if choice == "1":
             grouped_section_loop("CLKS", clks_options, all_options, values)
             continue
-        if choice == "2":
+        if choice == "2" and has_user:
             section_loop("USER", user_options, all_options, values)
             continue
+        if choice == "2" and not has_user:
+            print("user features unavailable in CLKS-only mode")
+            continue
         if choice in {"s", "save"}:
             return True
         if choice in {"q", "quit"}:
@@ -1870,6 +1941,7 @@ def parse_args() -> argparse.Namespace:
     parser.add_argument("--non-interactive", action="store_true", help="save config without opening interactive menu")
     parser.add_argument("--plain", action="store_true", help="use legacy plain-text menu instead of ncurses")
     parser.add_argument("--gui", action="store_true", help="use GUI window mode (PySide)")
+    parser.add_argument("--clks-only", action="store_true", help="only expose CLKS options and emit CLKS-only config")
     parser.add_argument(
         "--preset",
         choices=["full", "minimal", "dev"],
@@ -1892,10 +1964,13 @@ def main() -> int:
         raise RuntimeError("--gui and --plain cannot be used together")
 
     clks_options = load_clks_options()
-    user_options = discover_user_apps()
+    clks_only_mode = args.clks_only or not APPS_DIR.exists()
+    if clks_only_mode and not args.clks_only:
+        print(f"menuconfig: cleonos app directory not found, switching to CLKS-only mode ({APPS_DIR})")
+    user_options = [] if clks_only_mode else discover_user_apps()
     all_options = clks_options + user_options
 
-    previous = load_previous_values()
+    previous = load_previous_values(include_user=not clks_only_mode)
     values = init_values(all_options, previous, use_defaults=args.defaults)
 
     if args.preset:
@@ -1921,9 +1996,16 @@ def main() -> int:
         return 0
 
     final_eval = evaluate_config(all_options, values)
-    write_outputs(final_eval.effective, all_options)
+    write_outputs(final_eval.effective, clks_options, user_options)
     print(f"menuconfig: wrote {CONFIG_JSON_PATH}")
     print(f"menuconfig: wrote {CONFIG_CMAKE_PATH}")
+    print(f"menuconfig: wrote {CONFIG_CLKS_JSON_PATH}")
+    print(f"menuconfig: wrote {CONFIG_CLKS_CMAKE_PATH}")
+    if user_options:
+        print(f"menuconfig: wrote {CONFIG_CLEONOS_JSON_PATH}")
+        print(f"menuconfig: wrote {CONFIG_CLEONOS_CMAKE_PATH}")
+    else:
+        print("menuconfig: CLeonOS app config skipped (CLKS-only mode)")
     return 0