config/BoardConfigKernel.mk

# Copyright (C) 2018-2022 The LineageOS 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
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# Kernel build configuration variables
# ====================================
#
# These config vars are usually set in BoardConfig.mk:
#
#   TARGET_KERNEL_SOURCE               = Kernel source dir, optional, defaults
#                                          to kernel/$(TARGET_DEVICE_DIR)
#   TARGET_KERNEL_ARCH                 = Kernel Arch
#   TARGET_KERNEL_CROSS_COMPILE_PREFIX = Compiler prefix (e.g. arm-eabi-)
#                                          defaults to arm-linux-androidkernel- for arm
#                                                      aarch64-linux-android- for arm64
#                                                      x86_64-linux-android- for x86
#
#   TARGET_KERNEL_CLANG_COMPILE        = Compile kernel with clang, defaults to true
#   TARGET_KERNEL_LLVM_BINUTILS        = Use LLVM binutils, defaults to true
#   TARGET_KERNEL_VERSION              = Reported kernel version in top level kernel
#                                        makefile. Can be overriden in device trees
#                                        in the event of prebuilt kernel.
#
#   TARGET_KERNEL_DTBO_PREFIX          = Override path prefix of TARGET_KERNEL_DTBO.
#                                        Defaults to empty
#   TARGET_KERNEL_DTBO                 = Name of the kernel Makefile target that
#                                        generates dtbo.img. Defaults to dtbo.img
#   TARGET_KERNEL_DTB                  = Name of the kernel Makefile target that
#                                        generates the *.dtb targets. Defaults to dtbs
#
#   TARGET_KERNEL_EXT_MODULE_ROOT      = Optional, the external modules root directory
#                                          Defaults to empty
#   TARGET_KERNEL_EXT_MODULES          = Optional, the external modules we are
#                                          building. Defaults to empty
#
#   KERNEL_TOOLCHAIN_PREFIX            = Overrides TARGET_KERNEL_CROSS_COMPILE_PREFIX,
#                                          Set this var in shell to override
#                                          toolchain specified in BoardConfig.mk
#   KERNEL_TOOLCHAIN                   = Path to toolchain, if unset, assumes
#                                          TARGET_KERNEL_CROSS_COMPILE_PREFIX
#                                          is in PATH
#   USE_CCACHE                         = Enable ccache (global Android flag)

BUILD_TOP := $(abspath .)

TARGET_AUTO_KDIR := $(shell echo $(TARGET_DEVICE_DIR) | sed -e 's/^device/kernel/g')
TARGET_KERNEL_SOURCE ?= $(TARGET_AUTO_KDIR)

TARGET_KERNEL_ARCH := $(strip $(TARGET_KERNEL_ARCH))
ifeq ($(TARGET_KERNEL_ARCH),)
    KERNEL_ARCH := $(TARGET_ARCH)
else
    KERNEL_ARCH := $(TARGET_KERNEL_ARCH)
endif

KERNEL_VERSION := $(shell grep -s "^VERSION = " $(TARGET_KERNEL_SOURCE)/Makefile | awk '{ print $$3 }')
KERNEL_PATCHLEVEL := $(shell grep -s "^PATCHLEVEL = " $(TARGET_KERNEL_SOURCE)/Makefile | awk '{ print $$3 }')
TARGET_KERNEL_VERSION ?= $(shell echo $(KERNEL_VERSION)"."$(KERNEL_PATCHLEVEL))

CLANG_PREBUILTS := $(BUILD_TOP)/prebuilts/clang/host/$(HOST_PREBUILT_TAG)/clang-r450784d
GCC_PREBUILTS := $(BUILD_TOP)/prebuilts/gcc/$(HOST_PREBUILT_TAG)
# arm64 toolchain
KERNEL_TOOLCHAIN_arm64 := $(GCC_PREBUILTS)/aarch64/aarch64-linux-android-4.9/bin
KERNEL_TOOLCHAIN_PREFIX_arm64 := aarch64-linux-android-
# arm toolchain
KERNEL_TOOLCHAIN_arm := $(GCC_PREBUILTS)/arm/arm-linux-androideabi-4.9/bin
KERNEL_TOOLCHAIN_PREFIX_arm := arm-linux-androidkernel-
# x86 toolchain
KERNEL_TOOLCHAIN_x86 := $(GCC_PREBUILTS)/x86/x86_64-linux-android-4.9/bin
KERNEL_TOOLCHAIN_PREFIX_x86 := x86_64-linux-android-
TARGET_KERNEL_CROSS_COMPILE_PREFIX := $(strip $(TARGET_KERNEL_CROSS_COMPILE_PREFIX))
ifneq ($(TARGET_KERNEL_CROSS_COMPILE_PREFIX),)
    KERNEL_TOOLCHAIN_PREFIX ?= $(TARGET_KERNEL_CROSS_COMPILE_PREFIX)
else
    KERNEL_TOOLCHAIN ?= $(KERNEL_TOOLCHAIN_$(KERNEL_ARCH))
    KERNEL_TOOLCHAIN_PREFIX ?= $(KERNEL_TOOLCHAIN_PREFIX_$(KERNEL_ARCH))
endif

ifeq ($(KERNEL_TOOLCHAIN),)
    KERNEL_TOOLCHAIN_PATH := $(KERNEL_TOOLCHAIN_PREFIX)
else
    KERNEL_TOOLCHAIN_PATH := $(KERNEL_TOOLCHAIN)/$(KERNEL_TOOLCHAIN_PREFIX)
endif

# We need to add GCC toolchain to the path no matter what
# for tools like `as`
KERNEL_TOOLCHAIN_PATH_gcc := $(KERNEL_TOOLCHAIN_$(KERNEL_ARCH))

ifneq ($(USE_CCACHE),)
    ifneq ($(CCACHE_EXEC),)
        # Android 10+ deprecates use of a build ccache. Only system installed ones are now allowed
        CCACHE_BIN := $(CCACHE_EXEC)
    endif
endif

ifneq ($(TARGET_KERNEL_CLANG_COMPILE),false)
    KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(KERNEL_TOOLCHAIN_PATH)"
else
    KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(CCACHE_BIN) $(KERNEL_TOOLCHAIN_PATH)"
endif

# Needed for CONFIG_COMPAT_VDSO, safe to set for all arm64 builds
ifeq ($(KERNEL_ARCH),arm64)
    KERNEL_CROSS_COMPILE += CROSS_COMPILE_ARM32="$(KERNEL_TOOLCHAIN_arm)/$(KERNEL_TOOLCHAIN_PREFIX_arm)"
    KERNEL_CROSS_COMPILE += CROSS_COMPILE_COMPAT="$(KERNEL_TOOLCHAIN_arm)/$(KERNEL_TOOLCHAIN_PREFIX_arm)"
endif

prebuilt_build_tools_lineage := prebuilts/tools-lineage
prebuilt_build_tools_lineage_bin := $(prebuilt_build_tools_lineage)/$(HOST_PREBUILT_TAG)/bin

# Clear this first to prevent accidental poisoning from env
KERNEL_MAKE_FLAGS :=

# Add back threads, ninja cuts this to $(nproc)/2
KERNEL_MAKE_FLAGS += -j$(shell prebuilts/tools-lineage/$(HOST_PREBUILT_TAG)/bin/nproc --all)

ifeq ($(TARGET_KERNEL_CLANG_COMPILE),false)
    ifeq ($(KERNEL_ARCH),arm)
        # Avoid "Unknown symbol _GLOBAL_OFFSET_TABLE_" errors
        KERNEL_MAKE_FLAGS += CFLAGS_MODULE="-fno-pic"
    endif

    ifeq ($(KERNEL_ARCH),arm64)
        # Avoid "unsupported RELA relocation: 311" errors (R_AARCH64_ADR_GOT_PAGE)
        KERNEL_MAKE_FLAGS += CFLAGS_MODULE="-fno-pic"
    endif
endif

ifeq ($(HOST_OS),darwin)
    KERNEL_MAKE_FLAGS += HOSTCFLAGS="-I$(BUILD_TOP)/external/elfutils/libelf -I/usr/local/opt/openssl/include" HOSTLDFLAGS="-L/usr/local/opt/openssl/lib -fuse-ld=lld"
else
    KERNEL_MAKE_FLAGS += CPATH="/usr/include:/usr/include/x86_64-linux-gnu" HOSTLDFLAGS="-L/usr/lib/x86_64-linux-gnu -L/usr/lib64 -fuse-ld=lld"
endif

TOOLS_PATH_OVERRIDE := \
    LD_LIBRARY_PATH=$(BUILD_TOP)/prebuilts/tools-lineage/$(HOST_PREBUILT_TAG)/lib:$$LD_LIBRARY_PATH \
    PERL5LIB=$(BUILD_TOP)/prebuilts/tools-lineage/common/perl-base

ifeq ($(KERNEL_ARCH),arm64)
    # Add 32-bit GCC to PATH so that arm-linux-androidkernel-as is available for CONFIG_COMPAT_VDSO
    TOOLS_PATH_OVERRIDE += PATH=$(BUILD_TOP)/prebuilts/tools-lineage/$(HOST_PREBUILT_TAG)/bin:$(KERNEL_TOOLCHAIN_arm):$$PATH
else
    TOOLS_PATH_OVERRIDE += PATH=$(BUILD_TOP)/prebuilts/tools-lineage/$(HOST_PREBUILT_TAG)/bin:$$PATH
endif

# Set DTBO image locations so the build system knows to build them
ifeq (true,$(filter true, $(TARGET_NEEDS_DTBOIMAGE) $(BOARD_KERNEL_SEPARATED_DTBO)))
    TARGET_KERNEL_DTBO_PREFIX ?=
    TARGET_KERNEL_DTBO ?= dtbo.img
    BOARD_PREBUILT_DTBOIMAGE ?= $(TARGET_OUT_INTERMEDIATES)/DTBO_OBJ/arch/$(KERNEL_ARCH)/boot/$(TARGET_KERNEL_DTBO_PREFIX)$(TARGET_KERNEL_DTBO)
endif

# Set the default dtb target
TARGET_KERNEL_DTB ?= dtbs

# Set no external modules by default
TARGET_KERNEL_EXT_MODULE_ROOT ?=
TARGET_KERNEL_EXT_MODULES ?=

# Set use the full path to the make command
KERNEL_MAKE_CMD := $(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/make

# Set the full path to the clang command
KERNEL_MAKE_FLAGS += HOSTCC=$(CLANG_PREBUILTS)/bin/clang
KERNEL_MAKE_FLAGS += HOSTCXX=$(CLANG_PREBUILTS)/bin/clang++

# Use LLVM's substitutes for GNU binutils
ifneq ($(TARGET_KERNEL_CLANG_COMPILE), false)
    ifneq ($(TARGET_KERNEL_LLVM_BINUTILS), false)
        KERNEL_MAKE_FLAGS += LLVM=1 LLVM_IAS=1
        KERNEL_MAKE_FLAGS += LD=$(CLANG_PREBUILTS)/bin/ld.lld
        KERNEL_MAKE_FLAGS += AR=$(CLANG_PREBUILTS)/bin/llvm-ar
    endif
endif

# Since Linux 4.16, flex and bison are required
KERNEL_MAKE_FLAGS += LEX=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/flex
KERNEL_MAKE_FLAGS += YACC=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_PREBUILT_TAG)/bin/bison
KERNEL_MAKE_FLAGS += M4=$(BUILD_TOP)/prebuilts/build-tools/$(HOST_OS)-x86/bin/m4
TOOLS_PATH_OVERRIDE += BISON_PKGDATADIR=$(BUILD_TOP)/prebuilts/build-tools/common/bison

# Set the out dir for the kernel's O= arg
# This needs to be an absolute path, so only set this if the standard out dir isn't used
OUT_DIR_PREFIX := $(shell echo $(OUT_DIR) | sed -e 's|/target/.*$$||g')
KERNEL_BUILD_OUT_PREFIX :=
ifeq ($(OUT_DIR_PREFIX),out)
    KERNEL_BUILD_OUT_PREFIX := $(BUILD_TOP)/
endif