#
# Copyright (C) 2014-2019 The Android-x86 Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#

export LC_CTYPE := C
export LC_MESSAGES := C

ifneq ($(TARGET_NO_KERNEL),true)
ifeq ($(TARGET_PREBUILT_KERNEL),)

KERNEL_DIR ?= kernel

ifneq ($(filter x86%,$(TARGET_ARCH)),)
TARGET_KERNEL_ARCH ?= $(TARGET_ARCH)
KERNEL_TARGET := bzImage
TARGET_KERNEL_CONFIG ?= android-$(TARGET_KERNEL_ARCH)_defconfig
KERNEL_CONFIG_DIR := arch/x86/configs
endif
ifeq ($(TARGET_ARCH),arm)
KERNEL_TARGET := zImage
TARGET_KERNEL_CONFIG ?= goldfish_defconfig
KERNEL_CONFIG_DIR := arch/arm/configs
endif

ifeq ($(BUILD_KERNEL_WITH_CLANG),true)
CROSS_COMPILE := x86_64-linux-androidkernel-
KERNEL_CLANG_CLAGS := CC=clang HOSTCC=clang CLANG_TRIPLE=x86_64-linux-gnu- PATH=$(abspath $(LLVM_PREBUILTS_BASE)/$(BUILD_OS)-x86/$(LLVM_PREBUILTS_VERSION)/bin):$$PATH
else
ifeq ($(TARGET_KERNEL_ARCH),x86_64)
ifeq ($(HOST_OS),darwin)
CROSS_COMPILE ?= $(abspath prebuilts/gcc/darwin-x86/host/i686-apple-darwin-4.2.1/bin)/i686-apple-darwin11-
else
CROSS_COMPILE ?= $(abspath prebuilts/gcc/linux-x86/host/x86_64-linux-glibc2.11-4.6/bin)/x86_64-linux-
endif
else
CROSS_COMPILE ?= $(abspath $(TARGET_TOOLS_PREFIX))
endif
endif

KBUILD_OUTPUT := $(abspath $(TARGET_OUT_INTERMEDIATES)/kernel)
mk_kernel := + $(hide) $(MAKE) $(if $(filter darwin,$(HOST_OS)),-j$$(sysctl -n hw.ncpu) -l$$(($$(sysctl -n hw.ncpu)+2)),-j$$(nproc) -l$$(($$(nproc)+2))) \
	-C $(KERNEL_DIR) O=$(KBUILD_OUTPUT) ARCH=$(TARGET_ARCH) CROSS_COMPILE="$(abspath $(CC_WRAPPER)) $(CROSS_COMPILE)" $(if $(SHOW_COMMANDS),V=1) \
	YACC=$(abspath $(BISON)) LEX=$(abspath $(LEX)) \
	$(KERNEL_CLANG_CLAGS)

KERNEL_CONFIG_FILE := $(if $(wildcard $(TARGET_KERNEL_CONFIG)),$(TARGET_KERNEL_CONFIG),$(KERNEL_DIR)/$(KERNEL_CONFIG_DIR)/$(TARGET_KERNEL_CONFIG))

MOD_ENABLED := $(shell grep ^CONFIG_MODULES=y $(KERNEL_CONFIG_FILE))
FIRMWARE_ENABLED := $(shell grep ^CONFIG_FIRMWARE_IN_KERNEL=y $(KERNEL_CONFIG_FILE))

# I understand Android build system discourage to use submake,
# but I don't want to write a complex Android.mk to build kernel.
# This is the simplest way I can think.
KERNEL_DOTCONFIG_FILE := $(KBUILD_OUTPUT)/.config
KERNEL_ARCH_CHANGED := $(if $(filter 0,$(shell grep -s ^$(if $(filter x86,$(TARGET_KERNEL_ARCH)),\#.)CONFIG_64BIT $(KERNEL_DOTCONFIG_FILE) | wc -l)),FORCE)
$(KERNEL_DOTCONFIG_FILE): $(KERNEL_CONFIG_FILE) $(wildcard $(TARGET_KERNEL_DIFFCONFIG)) $(KERNEL_ARCH_CHANGED)
	$(hide) mkdir -p $(@D) && cat $(wildcard $^) > $@
	$(hide) ln -sf ../../../../../../external $(@D)
	$(mk_kernel) olddefconfig

BUILT_KERNEL_TARGET := $(KBUILD_OUTPUT)/arch/$(TARGET_ARCH)/boot/$(KERNEL_TARGET)
$(BUILT_KERNEL_TARGET): $(KERNEL_DOTCONFIG_FILE)
	$(mk_kernel) $(KERNEL_TARGET) $(if $(MOD_ENABLED),modules)
	$(if $(FIRMWARE_ENABLED),$(mk_kernel) INSTALL_MOD_PATH=$(abspath $(TARGET_OUT)) firmware_install)

ifneq ($(MOD_ENABLED),)
KERNEL_MODULES_DEP := $(firstword $(wildcard $(TARGET_OUT)/lib/modules/*/modules.dep))
KERNEL_MODULES_DEP := $(if $(KERNEL_MODULES_DEP),$(KERNEL_MODULES_DEP),$(TARGET_OUT)/lib/modules)

ALL_EXTRA_MODULES := $(patsubst %,$(TARGET_OUT_INTERMEDIATES)/kmodule/%,$(TARGET_EXTRA_KERNEL_MODULES))
$(ALL_EXTRA_MODULES): $(TARGET_OUT_INTERMEDIATES)/kmodule/%: $(BUILT_KERNEL_TARGET) | $(ACP)
	@echo Building additional kernel module $*
	$(hide) mkdir -p $(@D) && $(ACP) -fr $(EXTRA_KERNEL_MODULE_PATH_$*) $(@D)
	$(mk_kernel) M=$(abspath $@) modules || ( rm -rf $@ && exit 1 )

$(KERNEL_MODULES_DEP): $(BUILT_KERNEL_TARGET) $(ALL_EXTRA_MODULES)
	$(hide) rm -rf $(TARGET_OUT)/lib/modules
	$(mk_kernel) INSTALL_MOD_PATH=$(abspath $(TARGET_OUT)) modules_install
	+ $(hide) for kmod in $(TARGET_EXTRA_KERNEL_MODULES) ; do \
		echo Installing additional kernel module $${kmod} ; \
		$(subst +,,$(subst $(hide),,$(mk_kernel))) INSTALL_MOD_PATH=$(abspath $(TARGET_OUT)) M=$(abspath $(TARGET_OUT_INTERMEDIATES))/kmodule/$${kmod} modules_install ; \
	done
	$(hide) rm -f $(TARGET_OUT)/lib/modules/*/{build,source}
endif

$(BUILT_SYSTEMIMAGE): $(KERNEL_MODULES_DEP)

installclean: FILES += $(KBUILD_OUTPUT) $(INSTALLED_KERNEL_TARGET)

TARGET_PREBUILT_KERNEL := $(BUILT_KERNEL_TARGET)

.PHONY: kernel $(if $(KERNEL_ARCH_CHANGED),$(KERNEL_HEADERS_COMMON)/linux/binder.h)
kernel: $(INSTALLED_KERNEL_TARGET) $(KERNEL_MODULES_DEP)

endif # TARGET_PREBUILT_KERNEL

ifndef LINEAGE_BUILD
$(INSTALLED_KERNEL_TARGET): $(TARGET_PREBUILT_KERNEL) | $(ACP)
	$(copy-file-to-new-target)
ifdef TARGET_PREBUILT_MODULES
	mkdir -p $(TARGET_OUT)/lib
	$(hide) cp -r $(TARGET_PREBUILT_MODULES) $(TARGET_OUT)/lib
endif
endif # LINEAGE_BUILD
endif # KBUILD_OUTPUT