OPENSBI_VERSION_GIT=$(shell if [ -d $(src_dir)/.git ]; then git describe 2> /dev/null; fi)
# Setup compilation commands
+ifneq ($(LLVM),)
+CC = clang
+AR = llvm-ar
+LD = ld.lld
+OBJCOPY = llvm-objcopy
+else
ifdef CROSS_COMPILE
CC = $(CROSS_COMPILE)gcc
-CPP = $(CROSS_COMPILE)cpp
AR = $(CROSS_COMPILE)ar
LD = $(CROSS_COMPILE)ld
OBJCOPY = $(CROSS_COMPILE)objcopy
else
CC ?= gcc
-CPP ?= cpp
AR ?= ar
LD ?= ld
OBJCOPY ?= objcopy
endif
+endif
+CPP = $(CC) -E
AS = $(CC)
DTC = dtc
-# Guess the compillers xlen
-OPENSBI_CC_XLEN := $(shell TMP=`$(CC) -dumpmachine | sed 's/riscv\([0-9][0-9]\).*/\1/'`; echo $${TMP})
+ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
+CC_IS_CLANG = y
+else
+CC_IS_CLANG = n
+endif
+
+ifneq ($(shell $(LD) --version 2>&1 | head -n 1 | grep LLD),)
+LD_IS_LLD = y
+else
+LD_IS_LLD = n
+endif
+
+ifeq ($(CC_IS_CLANG),y)
+ifneq ($(CROSS_COMPILE),)
+CLANG_TARGET = --target=$(notdir $(CROSS_COMPILE:%-=%))
+endif
+endif
+
+# Guess the compiler's XLEN
+OPENSBI_CC_XLEN := $(shell TMP=`$(CC) $(CLANG_TARGET) -dumpmachine | sed 's/riscv\([0-9][0-9]\).*/\1/'`; echo $${TMP})
+
+# Guess the compiler's ABI and ISA
+ifneq ($(CC_IS_CLANG),y)
OPENSBI_CC_ABI := $(shell TMP=`$(CC) -v 2>&1 | sed -n 's/.*\(with\-abi=\([a-zA-Z0-9]*\)\).*/\2/p'`; echo $${TMP})
OPENSBI_CC_ISA := $(shell TMP=`$(CC) -v 2>&1 | sed -n 's/.*\(with\-arch=\([a-zA-Z0-9]*\)\).*/\2/p'`; echo $${TMP})
+endif
# Setup platform XLEN
ifndef PLATFORM_RISCV_XLEN
endif
endif
+ifeq ($(CC_IS_CLANG),y)
+ifeq ($(CROSS_COMPILE),)
+CLANG_TARGET = --target=riscv$(PLATFORM_RISCV_XLEN)-unknown-elf
+endif
+endif
+
+ifeq ($(LD_IS_LLD),y)
+RELAX_FLAG = -mno-relax
+USE_LD_FLAG = -fuse-ld=lld
+else
+USE_LD_FLAG = -fuse-ld=bfd
+endif
+
# Check whether the linker supports creating PIEs
-OPENSBI_LD_PIE := $(shell $(CC) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
+OPENSBI_LD_PIE := $(shell $(CC) $(CLANG_TARGET) $(RELAX_FLAG) $(USE_LD_FLAG) -fPIE -nostdlib -Wl,-pie -x c /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
# Setup list of objects.mk files
ifdef PLATFORM
endif
# Setup compilation commands flags
-GENFLAGS = -I$(platform_src_dir)/include
+ifeq ($(CC_IS_CLANG),y)
+GENFLAGS += $(CLANG_TARGET)
+GENFLAGS += -Wno-unused-command-line-argument
+endif
+GENFLAGS += -I$(platform_src_dir)/include
GENFLAGS += -I$(include_dir)
ifneq ($(OPENSBI_VERSION_GIT),)
GENFLAGS += -DOPENSBI_VERSION_GIT="\"$(OPENSBI_VERSION_GIT)\""
CFLAGS += -mno-save-restore -mstrict-align
CFLAGS += -mabi=$(PLATFORM_RISCV_ABI) -march=$(PLATFORM_RISCV_ISA)
CFLAGS += -mcmodel=$(PLATFORM_RISCV_CODE_MODEL)
+CFLAGS += $(RELAX_FLAG)
CFLAGS += $(GENFLAGS)
CFLAGS += $(platform-cflags-y)
CFLAGS += -fno-pie -no-pie
ASFLAGS += -mno-save-restore -mstrict-align
ASFLAGS += -mabi=$(PLATFORM_RISCV_ABI) -march=$(PLATFORM_RISCV_ISA)
ASFLAGS += -mcmodel=$(PLATFORM_RISCV_CODE_MODEL)
+ASFLAGS += $(RELAX_FLAG)
ASFLAGS += $(GENFLAGS)
ASFLAGS += $(platform-asflags-y)
ASFLAGS += $(firmware-asflags-y)
ARFLAGS = rcs
-ELFFLAGS += -Wl,--build-id=none -N -static-libgcc -lgcc
+ELFFLAGS += $(USE_LD_FLAG)
+ELFFLAGS += -Wl,--build-id=none -Wl,-N -static-libgcc -lgcc
ELFFLAGS += $(platform-ldflags-y)
ELFFLAGS += $(firmware-ldflags-y)
MERGEFLAGS += -r
+ifeq ($(LD_IS_LLD),y)
+MERGEFLAGS += -b elf
+else
MERGEFLAGS += -b elf$(PLATFORM_RISCV_XLEN)-littleriscv
+endif
MERGEFLAGS += -m elf$(PLATFORM_RISCV_XLEN)lriscv
DTSCPPFLAGS = $(CPPFLAGS) -nostdinc -nostdlib -fno-builtin -D__DTS__ -x assembler-with-cpp
------------------
OpenSBI can be compiled natively or cross-compiled on a x86 host. For
-cross-compilation, you can build your own toolchain or just download
-a prebuilt one from the [Bootlin toolchain repository].
+cross-compilation, you can build your own toolchain, download a prebuilt one
+from the [Bootlin toolchain repository] or install a distribution-provided
+toolchain; if you opt to use LLVM/Clang, most distribution toolchains will
+support cross-compiling for RISC-V using the same toolchain as your native
+LLVM/Clang toolchain due to LLVM's ability to support multiple backends in the
+same binary, so is often an easy way to obtain a working cross-compilation
+toolchain.
Please note that only a 64-bit version of the toolchain is available in
the Bootlin toolchain repository for now.
will generate 32-bit OpenSBI images. And vice vesa.
+Building with Clang/LLVM
+------------------------
+
+OpenSBI can also be built with Clang/LLVM. To build with just Clang but keep
+the default binutils (which will still use the *CROSS_COMPILE* prefix if
+defined), override the *CC* make variable with:
+```
+make CC=clang
+```
+
+To build with a full LLVM-based toolchain, not just Clang, enable the *LLVM*
+option with:
+```
+make LLVM=1
+```
+
+When using Clang, *CROSS_COMPILE* often does not need to be defined unless
+using GNU binutils with prefixed binary names. *PLATFORM_RISCV_XLEN* will be
+used to infer a default triple to pass to Clang, so if *PLATFORM_RISCV_XLEN*
+itself defaults to an undesired value then prefer setting that rather than the
+full triple via *CROSS_COMPILE*. If *CROSS_COMPILE* is nonetheless defined,
+rather than being used as a prefix for the executable name, it will instead be
+passed via the `--target` option with the trailing `-` removed, so must be a
+valid triple.
+
+These can also be mixed; for example using a GCC cross-compiler but LLVM
+binutils would be:
+```
+make CC=riscv64-unknown-elf-gcc LLVM=1
+```
+
+These variables must be passed for all the make invocations described in this
+document.
+
+NOTE: Using Clang with a `riscv*-linux-gnu` GNU binutils linker has been seen
+to produce broken binaries with missing relocations; it is therefore currently
+recommended that this combination be avoided or *FW_PIC=n* be used to disable
+building OpenSBI as a position-independent binary.
+
Contributing to OpenSBI
-----------------------
projects / platform / kernel / opensbi.git / commitdiff