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tasks: kernel: Add support for Clang kernel builds
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Add support for compiling kernels with Clang as intoduced on android-4.4

In order to compile with clang, you must set TARGET_KERNEL_CLANG_COMPILE.
If you wish to specify a specific clang version, also set TARGET_KERNEL_CLANG_VERSION,
but if that is not set, the build system will default to the latest version of clang
available in prebuilts/clang

Change-Id: I79dc1dca9758a930f2f5ba1754b5d8de114af900
Signed-off-by: Joe Maples <joe@frap129.org>
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@Rashed97
Joe Maples authored and Rashed97 committed Dec 31, 2017
1 parent bf38db2 commit da32895
Showing 1 changed file with 59 additions and 21 deletions.
80 changes: 59 additions & 21 deletions build/tasks/kernel.mk
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,12 @@
# aarch64-linux-androidkernel- for arm64
# x86_64-linux-androidkernel- for x86
#
# TARGET_KERNEL_CLANG_COMPILE = Compile kernel with clang, defaults to false
#
# TARGET_KERNEL_CLANG_VERSION = Clang prebuilts version, optional, defaults to clang-stable
#
# TARGET_KERNEL_CLANG_PATH = Clang prebuilts path, optional
#
# BOARD_KERNEL_IMAGE_NAME = Built image name
# for ARM use: zImage
# for ARM64 use: Image.gz
Expand All @@ -50,6 +56,15 @@
# KERNEL_TOOLCHAIN = Path to toolchain, if unset, assumes
# TARGET_KERNEL_CROSS_COMPILE_PREFIX
# is in PATH
#
# KERNEL_CC = The C Compiler used. This is automatically set based
# on whether the clang version is set, optional.
#
# KERNEL_CLANG_TRIPLE = Target triple for clang (e.g. aarch64-linux-gnu-)
# defaults to arm-linux-gnu- for arm
# aarch64-linux-gnu- for arm64
# x86_64-linux-gnu- for x86
#
# USE_CCACHE = Enable ccache (global Android flag)
#
# NEED_KERNEL_MODULE_ROOT = Optional, if true, install kernel
Expand Down Expand Up @@ -225,6 +240,24 @@ KERNEL_TOOLCHAIN_PATH := $(KERNEL_TOOLCHAIN)/$(KERNEL_TOOLCHAIN_PREFIX)
endif
endif

ifeq ($(TARGET_KERNEL_CLANG_COMPILE),true)
ifneq ($(TARGET_KERNEL_CLANG_VERSION),)
# Find the clang-* directory containing the specified version
KERNEL_CLANG_VERSION := $(shell find $(ANDROID_BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/ -name AndroidVersion.txt -exec grep -l $(TARGET_KERNEL_CLANG_VERSION) "{}" \; | sed -e 's|/AndroidVersion.txt$$||g;s|^.*/||g')
else
# Only set the latest version of clang if TARGET_KERNEL_CLANG_VERSION hasn't been set by the device config
KERNEL_CLANG_VERSION := $(shell ls -d $(ANDROID_BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/clang-* | xargs -n 1 basename | tail -1)
endif
TARGET_KERNEL_CLANG_PATH ?= $(ANDROID_BUILD_TOP)/prebuilts/clang/host/$(HOST_OS)-x86/$(KERNEL_CLANG_VERSION)/bin
ifeq ($(KERNEL_ARCH),arm64)
KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=aarch64-linux-gnu-
else ifeq ($(KERNEL_ARCH),arm)
KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=arm-linux-gnu-
else ifeq ($(KERNEL_ARCH),x86)
KERNEL_CLANG_TRIPLE ?= CLANG_TRIPLE=x86_64-linux-gnu-
endif
endif

ifneq ($(USE_CCACHE),)
# Detect if the system already has ccache installed to use instead of the prebuilt
ccache := $(shell which ccache)
Expand All @@ -236,7 +269,12 @@ ifneq ($(USE_CCACHE),)
endif
endif

KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(ccache) $(KERNEL_TOOLCHAIN_PATH)"
ifeq ($(TARGET_KERNEL_CLANG_COMPILE),true)
KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(KERNEL_TOOLCHAIN_PATH)"
KERNEL_CC ?= CC="$(ccache) $(TARGET_KERNEL_CLANG_PATH)/clang"
else
KERNEL_CROSS_COMPILE := CROSS_COMPILE="$(ccache) $(KERNEL_TOOLCHAIN_PATH)"
endif
ccache =

ifeq ($(HOST_OS),darwin)
Expand All @@ -263,35 +301,35 @@ $(KERNEL_ADDITIONAL_CONFIG_OUT): force_additional_config

$(KERNEL_CONFIG): $(KERNEL_OUT_STAMP) $(KERNEL_DEFCONFIG_SRC) $(KERNEL_ADDITIONAL_CONFIG_OUT)
@echo "Building Kernel Config"
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_DEFCONFIG)
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_DEFCONFIG)
$(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \
echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \
echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) oldconfig; fi
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) oldconfig; fi
# Create defconfig build artifact
$(hide) $(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) savedefconfig
$(hide) $(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) savedefconfig
$(hide) if [ ! -z "$(KERNEL_ADDITIONAL_CONFIG)" ]; then \
echo "Using additional config '$(KERNEL_ADDITIONAL_CONFIG)'"; \
$(KERNEL_SRC)/scripts/kconfig/merge_config.sh -m -O $(KERNEL_OUT) $(KERNEL_OUT)/.config $(KERNEL_SRC)/arch/$(KERNEL_ARCH)/configs/$(KERNEL_ADDITIONAL_CONFIG); \
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) KCONFIG_ALLCONFIG=$(KERNEL_OUT)/.config alldefconfig; fi
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) KCONFIG_ALLCONFIG=$(KERNEL_OUT)/.config alldefconfig; fi

TARGET_KERNEL_BINARIES: $(KERNEL_OUT_STAMP) $(KERNEL_CONFIG) $(KERNEL_HEADERS_INSTALL_STAMP)
@echo "Building Kernel"
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(BOARD_KERNEL_IMAGE_NAME)
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(BOARD_KERNEL_IMAGE_NAME)
$(hide) if grep -q '^CONFIG_OF=y' $(KERNEL_CONFIG); then \
echo "Building DTBs"; \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) dtbs; \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) dtbs; \
fi
$(hide) if grep -q '^CONFIG_MODULES=y' $(KERNEL_CONFIG); then \
echo "Building Kernel Modules"; \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) modules; \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) modules; \
fi

.PHONY: INSTALLED_KERNEL_MODULES
INSTALLED_KERNEL_MODULES:
$(hide) if grep -q '^CONFIG_MODULES=y' $(KERNEL_CONFIG); then \
echo "Installing Kernel Modules"; \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) INSTALL_MOD_PATH=../../$(KERNEL_MODULES_INSTALL) modules_install && \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) INSTALL_MOD_PATH=../../$(KERNEL_MODULES_INSTALL) modules_install && \
mofile=$$(find $(KERNEL_MODULES_OUT) -type f -name modules.order) && \
mpath=$$(dirname $$mofile) && \
for f in $$(find $$mpath/kernel -type f -name '*.ko'); do \
Expand All @@ -313,47 +351,47 @@ $(KERNEL_HEADERS_INSTALL_STAMP): $(KERNEL_OUT_STAMP) $(KERNEL_CONFIG)
@echo "Building Kernel Headers"
$(hide) if [ ! -z "$(KERNEL_HEADER_DEFCONFIG)" ]; then \
rm -f ../$(KERNEL_CONFIG); \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) $(KERNEL_CROSS_COMPILE) VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_HEADER_DEFCONFIG); \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) $(KERNEL_CROSS_COMPILE) headers_install; fi
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_HEADER_DEFCONFIG); \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_HEADER_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) headers_install; fi
$(hide) if [ "$(KERNEL_HEADER_DEFCONFIG)" != "$(KERNEL_DEFCONFIG)" ]; then \
echo "Used a different defconfig for header generation"; \
rm -f ../$(KERNEL_CONFIG); \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_DEFCONFIG); fi
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_DEFCONFIG); fi
$(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \
echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \
echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) oldconfig; fi
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) oldconfig; fi
$(hide) if [ ! -z "$(KERNEL_ADDITIONAL_CONFIG)" ]; then \
echo "Using additional config '$(KERNEL_ADDITIONAL_CONFIG)'"; \
$(KERNEL_SRC)/scripts/kconfig/merge_config.sh -m -O $(KERNEL_OUT) $(KERNEL_OUT)/.config $(KERNEL_SRC)/arch/$(KERNEL_ARCH)/configs/$(KERNEL_ADDITIONAL_CONFIG); \
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) KCONFIG_ALLCONFIG=$(KERNEL_OUT)/.config alldefconfig; fi
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) KCONFIG_ALLCONFIG=$(KERNEL_OUT)/.config alldefconfig; fi
$(hide) touch $@

# provide this rule because there are dependencies on this throughout the repo
$(KERNEL_HEADERS_INSTALL): $(KERNEL_HEADERS_INSTALL_STAMP)

kerneltags: $(KERNEL_OUT_STAMP) $(KERNEL_CONFIG)
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) tags
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) tags

kernelconfig: KERNELCONFIG_MODE := menuconfig
kernelxconfig: KERNELCONFIG_MODE := xconfig
kernelxconfig kernelconfig: $(KERNEL_OUT_STAMP)
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG)
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(KERNEL_DEFCONFIG)
env KCONFIG_NOTIMESTAMP=true \
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNELCONFIG_MODE)
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(KERNELCONFIG_MODE)
env KCONFIG_NOTIMESTAMP=true \
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) savedefconfig
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) savedefconfig
cp $(KERNEL_OUT)/defconfig $(KERNEL_DEFCONFIG_SRC)

kernelsavedefconfig: $(KERNEL_OUT_STAMP)
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_DEFCONFIG)
$(MAKE) $(MAKE_FLAGS) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) $(KERNEL_DEFCONFIG)
env KCONFIG_NOTIMESTAMP=true \
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) savedefconfig
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) savedefconfig
cp $(KERNEL_OUT)/defconfig $(KERNEL_DEFCONFIG_SRC)

alldefconfig: $(KERNEL_OUT_STAMP)
env KCONFIG_NOTIMESTAMP=true \
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) alldefconfig
$(MAKE) -C $(KERNEL_SRC) O=$(KERNEL_OUT) ARCH=$(KERNEL_ARCH) $(KERNEL_CROSS_COMPILE) $(KERNEL_CLANG_TRIPLE) $(KERNEL_CC) alldefconfig

endif # FULL_KERNEL_BUILD

Expand Down

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