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# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2026 Richard Qin
#
# scripts/Kconfig.mk — Kernel Configuration Infrastructure
#
# This file is the heart of the LumeOS build-time configuration system.
# It mirrors the role of Linux's Kconfig + auto.conf pipeline:
#
# 1. Developer edits `.config` (or copies from arch/$(ARCH)/defconfig)
# 2. This file reads `.config`, applies defaults for anything missing,
# validates constraints, and exports two things:
# a) KCPPFLAGS — a set of -DCONFIG_xxx=value flags for the compiler
# b) $(BUILD)/generated/autoconf.h — the same values as C #defines
#
# Design Principles (matching Linux conventions):
# - Every CONFIG_ symbol has a default defined HERE, so a bare `make`
# with no .config still builds a sane kernel.
# - Boolean options use 'y' / 'n'. Numeric options are plain integers.
# - The generated autoconf.h uses the exact same names so that
# `#ifdef CONFIG_DEBUG` works identically in Makefile and C.
# ======================================================================
# ------------------------------------------------------------------
# §1 Read user configuration (if it exists)
# ------------------------------------------------------------------
-include .config
# ------------------------------------------------------------------
# §2 Provide defaults for every CONFIG_ symbol
#
# ?= means "set only if not already set (by .config or CLI)".
# This is the single source of truth for default values.
# ------------------------------------------------------------------
# --- Platform -------------------------------------------------------
CONFIG_ARCH ?= riscv
# --- CPU / SMP ------------------------------------------------------
CONFIG_NR_CPUS ?= 8
# --- Scheduler ------------------------------------------------------
CONFIG_HZ ?= 100
CONFIG_NR_PRIORITIES ?= 32
# --- Memory Management ----------------------------------------------
CONFIG_PAGE_SIZE ?= 4096
CONFIG_MAX_ORDER ?= 11
CONFIG_KERNEL_STACK_SIZE ?= 8192
# --- Security / Hardening -------------------------------------------
CONFIG_KASLR ?= y
CONFIG_KASLR_POLICY_ID ?= 0
CONFIG_KASLR_LOG_LEVEL ?= 1
CONFIG_STACK_CANARY ?= y
CONFIG_KERNEL_COMPRESSED ?= y
# --- Debug -----------------------------------------------------------
CONFIG_DEBUG ?= y
CONFIG_DEBUG_LOCKS ?= y
CONFIG_SELFTEST ?= y
CONFIG_KLOG ?= y
# --- Initramfs ------------------------------------------------------
# Source for the initramfs image. Accepted forms (auto-detected by
# scripts/gen_initramfs.sh):
# - a listing file (gen_init_cpio format) → built into a cpio
# - a directory → packed recursively
# - a *.cpio file → used as-is
# Override on the command line or pin in .config:
# make all CONFIG_INITRAMFS_SOURCE=/path/to/rootfs
CONFIG_INITRAMFS_SOURCE ?= usr/default_cpio_list
CONFIG_INITRAMFS_ROOT_UID ?= 0
CONFIG_INITRAMFS_ROOT_GID ?= 0
# ------------------------------------------------------------------
# §3 Derived constants (computed from CONFIG_ symbols)
#
# These follow Linux's pattern of expressing dependent values
# so that C code never has to do its own derivation at runtime.
# ------------------------------------------------------------------
# Default priority = middle of the range
CONFIG_DEFAULT_PRIORITY = $(shell echo $$(( $(CONFIG_NR_PRIORITIES) / 2 )))
# Idle priority = lowest = NR_PRIORITIES - 1
CONFIG_IDLE_PRIORITY = $(shell echo $$(( $(CONFIG_NR_PRIORITIES) - 1 )))
# Default time slice in ticks: 100ms worth of ticks
# (same as Linux CFS's sysctl_sched_min_granularity default)
CONFIG_DEFAULT_TIMESLICE = $(shell echo $$(( $(CONFIG_HZ) / 10 )))
# ------------------------------------------------------------------
# §4 Export to C/C++ via -D flags
#
# KCPPFLAGS is appended to CFLAGS/CXXFLAGS in the main Makefile.
# Every CONFIG_xxx=<value> becomes -DCONFIG_xxx=<value>.
# Boolean 'y' options become -DCONFIG_xxx=1.
# ------------------------------------------------------------------
KCPPFLAGS :=
# Numeric options — pass through as-is
KCPPFLAGS += -DCONFIG_NR_CPUS=$(CONFIG_NR_CPUS)
KCPPFLAGS += -DCONFIG_HZ=$(CONFIG_HZ)
KCPPFLAGS += -DCONFIG_NR_PRIORITIES=$(CONFIG_NR_PRIORITIES)
KCPPFLAGS += -DCONFIG_DEFAULT_PRIORITY=$(CONFIG_DEFAULT_PRIORITY)
KCPPFLAGS += -DCONFIG_IDLE_PRIORITY=$(CONFIG_IDLE_PRIORITY)
KCPPFLAGS += -DCONFIG_DEFAULT_TIMESLICE=$(CONFIG_DEFAULT_TIMESLICE)
KCPPFLAGS += -DCONFIG_PAGE_SIZE=$(CONFIG_PAGE_SIZE)
KCPPFLAGS += -DCONFIG_MAX_ORDER=$(CONFIG_MAX_ORDER)
KCPPFLAGS += -DCONFIG_KERNEL_STACK_SIZE=$(CONFIG_KERNEL_STACK_SIZE)
# Boolean options — translate 'y' → 1
ifeq ($(CONFIG_KASLR),y)
KCPPFLAGS += -DCONFIG_KASLR=1
endif
KCPPFLAGS += -DCONFIG_KASLR_POLICY_ID=$(CONFIG_KASLR_POLICY_ID)
KCPPFLAGS += -DCONFIG_KASLR_LOG_LEVEL=$(CONFIG_KASLR_LOG_LEVEL)
ifeq ($(CONFIG_STACK_CANARY),y)
KCPPFLAGS += -DCONFIG_STACK_CANARY=1
endif
ifeq ($(CONFIG_DEBUG),y)
KCPPFLAGS += -DCONFIG_DEBUG=1
endif
ifeq ($(CONFIG_DEBUG_LOCKS),y)
KCPPFLAGS += -DCONFIG_DEBUG_LOCKS=1
endif
ifeq ($(CONFIG_SELFTEST),y)
KCPPFLAGS += -DCONFIG_SELFTEST=1
endif
ifeq ($(CONFIG_KLOG),y)
KCPPFLAGS += -DCONFIG_KLOG=1
endif
ifeq ($(CONFIG_KERNEL_COMPRESSED),y)
KCPPFLAGS += -DCONFIG_KERNEL_COMPRESSED=1
endif
# ------------------------------------------------------------------
# §5 Generate autoconf.h (analogous to Linux's include/generated/autoconf.h)
#
# This header is auto-generated at build time so that C code can
# #include <generated/autoconf.h> and see CONFIG_xxx macros without
# relying on -D flags alone. This is important for IDE integration.
# ------------------------------------------------------------------
AUTOCONF_H := $(BUILD)/generated/autoconf.h
define generate-autoconf
@mkdir -p $(dir $(AUTOCONF_H))
@echo " GEN $(AUTOCONF_H)"
@echo "/* AUTO-GENERATED — DO NOT EDIT */" > $(AUTOCONF_H)
@echo "/* Generated by scripts/Kconfig.mk */" >> $(AUTOCONF_H)
@echo "#pragma once" >> $(AUTOCONF_H)
@echo "" >> $(AUTOCONF_H)
@echo "/* Platform */" >> $(AUTOCONF_H)
@echo "#define CONFIG_NR_CPUS $(CONFIG_NR_CPUS)" >> $(AUTOCONF_H)
@echo "" >> $(AUTOCONF_H)
@echo "/* Scheduler */" >> $(AUTOCONF_H)
@echo "#define CONFIG_HZ $(CONFIG_HZ)" >> $(AUTOCONF_H)
@echo "#define CONFIG_NR_PRIORITIES $(CONFIG_NR_PRIORITIES)" >> $(AUTOCONF_H)
@echo "#define CONFIG_DEFAULT_PRIORITY $(CONFIG_DEFAULT_PRIORITY)" >> $(AUTOCONF_H)
@echo "#define CONFIG_IDLE_PRIORITY $(CONFIG_IDLE_PRIORITY)" >> $(AUTOCONF_H)
@echo "#define CONFIG_DEFAULT_TIMESLICE $(CONFIG_DEFAULT_TIMESLICE)" >> $(AUTOCONF_H)
@echo "" >> $(AUTOCONF_H)
@echo "/* Memory Management */" >> $(AUTOCONF_H)
@echo "#define CONFIG_PAGE_SIZE $(CONFIG_PAGE_SIZE)" >> $(AUTOCONF_H)
@echo "#define CONFIG_MAX_ORDER $(CONFIG_MAX_ORDER)" >> $(AUTOCONF_H)
@echo "#define CONFIG_KERNEL_STACK_SIZE $(CONFIG_KERNEL_STACK_SIZE)" >> $(AUTOCONF_H)
@echo "" >> $(AUTOCONF_H)
@echo "/* Security */" >> $(AUTOCONF_H)
$(if $(filter y,$(CONFIG_KASLR)), @echo "#define CONFIG_KASLR 1" >> $(AUTOCONF_H))
@echo "#define CONFIG_KASLR_POLICY_ID $(CONFIG_KASLR_POLICY_ID)" >> $(AUTOCONF_H)
@echo "#define CONFIG_KASLR_LOG_LEVEL $(CONFIG_KASLR_LOG_LEVEL)" >> $(AUTOCONF_H)
$(if $(filter y,$(CONFIG_STACK_CANARY)), @echo "#define CONFIG_STACK_CANARY 1" >> $(AUTOCONF_H))
@echo "" >> $(AUTOCONF_H)
@echo "/* Debug */" >> $(AUTOCONF_H)
$(if $(filter y,$(CONFIG_DEBUG)), @echo "#define CONFIG_DEBUG 1" >> $(AUTOCONF_H))
$(if $(filter y,$(CONFIG_DEBUG_LOCKS)), @echo "#define CONFIG_DEBUG_LOCKS 1" >> $(AUTOCONF_H))
$(if $(filter y,$(CONFIG_SELFTEST)), @echo "#define CONFIG_SELFTEST 1" >> $(AUTOCONF_H))
$(if $(filter y,$(CONFIG_KLOG)), @echo "#define CONFIG_KLOG 1" >> $(AUTOCONF_H))
$(if $(filter y,$(CONFIG_KERNEL_COMPRESSED)), @echo "#define CONFIG_KERNEL_COMPRESSED 1" >> $(AUTOCONF_H))
endef
# ------------------------------------------------------------------
# §6 Utility targets
# ------------------------------------------------------------------
# 'make defconfig' — reset .config to the arch default
.PHONY: defconfig savedefconfig showconfig
defconfig:
@echo " DEFCFG arch/$(CONFIG_ARCH)/defconfig → .config"
@cp arch/$(CONFIG_ARCH)/defconfig .config
# 'make savedefconfig' — save current effective config
savedefconfig:
@echo " SAVE .config"
@echo "# LumeOS Kernel Configuration (saved $$(date +%Y-%m-%d))" > .config
@echo "CONFIG_ARCH = $(CONFIG_ARCH)" >> .config
@echo "CONFIG_NR_CPUS = $(CONFIG_NR_CPUS)" >> .config
@echo "CONFIG_HZ = $(CONFIG_HZ)" >> .config
@echo "CONFIG_NR_PRIORITIES = $(CONFIG_NR_PRIORITIES)" >> .config
@echo "CONFIG_PAGE_SIZE = $(CONFIG_PAGE_SIZE)" >> .config
@echo "CONFIG_MAX_ORDER = $(CONFIG_MAX_ORDER)" >> .config
@echo "CONFIG_KERNEL_STACK_SIZE = $(CONFIG_KERNEL_STACK_SIZE)" >> .config
@echo "CONFIG_KASLR = $(CONFIG_KASLR)" >> .config
@echo "CONFIG_KASLR_POLICY_ID = $(CONFIG_KASLR_POLICY_ID)" >> .config
@echo "CONFIG_KASLR_LOG_LEVEL = $(CONFIG_KASLR_LOG_LEVEL)" >> .config
@echo "CONFIG_STACK_CANARY = $(CONFIG_STACK_CANARY)" >> .config
@echo "CONFIG_DEBUG = $(CONFIG_DEBUG)" >> .config
@echo "CONFIG_DEBUG_LOCKS = $(CONFIG_DEBUG_LOCKS)" >> .config
@echo "CONFIG_SELFTEST = $(CONFIG_SELFTEST)" >> .config
@echo "CONFIG_KLOG = $(CONFIG_KLOG)" >> .config
@echo "CONFIG_KERNEL_COMPRESSED = $(CONFIG_KERNEL_COMPRESSED)" >> .config
# 'make showconfig' — print effective configuration
showconfig:
@echo "========================================"
@echo " LumeOS Effective Configuration"
@echo "========================================"
@echo " ARCH = $(CONFIG_ARCH)"
@echo " NR_CPUS = $(CONFIG_NR_CPUS)"
@echo " HZ = $(CONFIG_HZ)"
@echo " NR_PRIORITIES = $(CONFIG_NR_PRIORITIES)"
@echo " DEFAULT_PRIORITY = $(CONFIG_DEFAULT_PRIORITY)"
@echo " IDLE_PRIORITY = $(CONFIG_IDLE_PRIORITY)"
@echo " DEFAULT_TIMESLICE = $(CONFIG_DEFAULT_TIMESLICE)"
@echo " PAGE_SIZE = $(CONFIG_PAGE_SIZE)"
@echo " MAX_ORDER = $(CONFIG_MAX_ORDER)"
@echo " KERNEL_STACK_SIZE = $(CONFIG_KERNEL_STACK_SIZE)"
@echo " KASLR = $(CONFIG_KASLR)"
@echo " KASLR_POLICY_ID = $(CONFIG_KASLR_POLICY_ID)"
@echo " KASLR_LOG_LEVEL = $(CONFIG_KASLR_LOG_LEVEL)"
@echo " STACK_CANARY = $(CONFIG_STACK_CANARY)"
@echo " DEBUG = $(CONFIG_DEBUG)"
@echo " DEBUG_LOCKS = $(CONFIG_DEBUG_LOCKS)"
@echo " SELFTEST = $(CONFIG_SELFTEST)"
@echo " KLOG = $(CONFIG_KLOG)"
@echo " KERNEL_COMPRESSED = $(CONFIG_KERNEL_COMPRESSED)"
@echo "========================================"
|
