bsb2/tools/build.mk

# Build the kernel

# Top Level Folder all generated files will be placed in.
ROOTBUILDDIR =  build
# Folder the generated files will be placed in.
BUILDDIR ?= $(ROOTBUILDDIR)
# Build folder suffixes
OPTTAG = opt
NOOPTTAG = noopt
DBGTAG = dbg
VERBOSETAG = verbose

# C++
CXX ?= $(PREFIX)clang++
# on macos the default compiler is called c++, switch to clang++
ifeq ($(shell uname),Darwin)
	ifeq ($(CXX),c++)
		CXX := clang++
	endif
endif

CXXFLAGS_ARCH = -m64
CXXFLAGS_DEFAULT = -std=c++23 -ffreestanding -fno-pic -nodefaultlibs -nostdlib -nostdinc -I. -fno-rtti -fno-exceptions -Wno-write-strings -fno-stack-protector -mno-red-zone -g -gdwarf-2 -fno-use-cxa-atexit -no-pie -nostartfiles
# Enable 16-byte compare-and-exchange instruction for debugging purposes (stack alignment)
CXXFLAGS_DEFAULT += -mcx16
CXXFLAGS_OPT = -O3 -fomit-frame-pointer
CXXFLAGS_WARNING = -Wall -Wextra -Werror -Wno-error=unused-parameter -Wno-error=unused-variable -Wno-non-virtual-dtor
CXXFLAGS_CLANG = -Wno-error=unused-private-field -Wno-implicit-exception-spec-mismatch -Wno-error=unused-const-variable -Wno-unused-command-line-argument -Wno-unused-const-variable -fno-strict-aliasing
ifeq ($(shell uname),Darwin)
	CXXFLAGS_CLANG += -target x86_64-pc-linux-gnu -fuse-ld=lld
endif
CXXFLAGS_GCC = -fno-tree-loop-distribute-patterns -Wstack-usage=4096 -Wno-error=stack-usage=
CXXFLAGS_NOFPU = -mno-mmx -mno-sse -mgeneral-regs-only
CXXFLAGS = $(CXXFLAGS_ARCH) $(CXXFLAGS_DEFAULT) $(CXXFLAGS_OPT) $(CXXFLAGS_NOFPU) $(CXXFLAGS_WARNING)
# Compiler specific flags
ifneq (,$(findstring clang,$(CXX)))
	COMPILER := CLANG
	CXXFLAGS += $(CXXFLAGS_CLANG)
else ifneq (,$(findstring g++,$(CXX)))
	COMPILER := GCC
	# Configures -Warray-bounds warning to allow accessing in the NULL page
	# Necessary to read the Extended BIOS Data Area at 0x40e
	ifeq "$(shell expr `$(CXX) -dumpversion | cut -f1 -d.` \>= 12)" "1"
		CXXFLAGS += --param=min-pagesize=0x40e
	endif
	CXXFLAGS += $(CXXFLAGS_GCC)
else
	COMPILER :=
endif

# Assembly
ASM = nasm
ASMFLAGS = -f elf64

# Additional build utilities
# If llvm tools are available, use them
ifneq (,$(shell which llvm-objcopy 2>/dev/null))
	PREFIX = llvm-
endif
OBJCOPY = $(PREFIX)objcopy
STRIP = $(PREFIX)strip
AR = $(PREFIX)ar

# Subdirectories with sources
VPATH = $(sort $(dir $(CC_SOURCES) $(ASM_SOURCES)))

# Lists of object files that are generated by compilation:
# Note that the variables containing the input files are to be defined by
# the Makefiles prior to including this common.mk.
CC_OBJECTS = $(addprefix $(BUILDDIR)/,$(CC_SOURCES:.cc=.o))
DEP_FILES = $(addprefix $(BUILDDIR)/,$(CC_SOURCES:.cc=.d) $(addsuffix .d,$(ASM_SOURCES)))
ASM_OBJECTS = $(addprefix $(BUILDDIR)/,$(addsuffix .o,$(ASM_SOURCES)))

# Dependency files
$(BUILDDIR)/%.d : %.cc $(MAKEFILE_LIST)
	@echo "DEP		$<"
	@mkdir -p $(@D)
	$(VERBOSE) $(CXX) $(CXXFLAGS) -MM -MT $(BUILDDIR)/$*.o -MF $@ $<


$(BUILDDIR)/%.asm.d : %.asm $(MAKEFILE_LIST)
	@echo "DEP		$<"
	@mkdir -p $(@D)
	$(VERBOSE) $(ASM) $(ASMFLAGS) -M -MT $(BUILDDIR)/$*.asm.o -MF $@ $<


# Object files
$(BUILDDIR)/%.o : %.cc $(MAKEFILE_LIST)
	@echo "CXX		$<"
	@mkdir -p $(@D)
	$(VERBOSE) $(CXX) -c $(CXXFLAGS) -o $@ $<

$(BUILDDIR)/%.asm.o : %.asm $(MAKEFILE_LIST)
	@echo "ASM		$<"
	@mkdir -p $(@D)
	$(VERBOSE) $(ASM) $(ASMFLAGS) -o $@ $<


# The standard target 'clean' removes the whole generated system, the object files, and the dependency files.
clean::
	rm -rf "$(BUILDDIR)"
	rm -rf doc

# Target issuing a nested call to make generating a fully optimized systems without assertions.
%-$(OPTTAG):
	$(VERBOSE) $(MAKE) BUILDDIR="$(BUILDDIR)/$(OPTTAG)" ISODIR="$(ISODIR)/$(OPTTAG)" CXXFLAGS_OPT="-Ofast -fomit-frame-pointer -flto -march=westmere -DNDEBUG" $*


# Target issuing a nested call to make generating a non-optimized system.
%-$(NOOPTTAG):
	$(VERBOSE) $(MAKE) BUILDDIR="$(BUILDDIR)/$(NOOPTTAG)" ISODIR="$(ISODIR)/$(NOOPTTAG)" CXXFLAGS_OPT="-O0" $*


# Target issuing a nested call to make generating a system optimized for debugging.
%-$(DBGTAG):
	$(VERBOSE) $(MAKE) BUILDDIR="$(BUILDDIR)/$(DBGTAG)" ISODIR="$(ISODIR)/$(DBGTAG)" CXXFLAGS_OPT="-Og -fno-omit-frame-pointer" $*


# Target issuing a nested call to make generating a system with verbose output.
%-$(VERBOSETAG):
	$(VERBOSE) $(MAKE) BUILDDIR="$(BUILDDIR)/$(VERBOSETAG)" ISODIR="$(ISODIR)/$(VERBOSETAG)" CXXFLAGS_OPT="-DVERBOSE" $*

# Build the doxygen docs
doc:
	PROJECT_NAME=StuBS doxygen ../doxygen/doxy-sra.cfg

# Documentation
help::
	@$(echo) "" \
		"All targets exist in different flavours in addition to \e[2;3m<name>\e[0m:\n" \
		"\e[2;3m<name>\e[0;3m-noopt\e[0m, \e[2;3m<name>\e[0;3m-opt\e[0m, \e[2;3m<name>\e[0;3m-dbg\e[0m, and \e[2;3m<name>\e[0;3m-verbose\e[0m.\n" \
		"Targets suffixed with \e[3m-noopt\e[0m are compiled without optimizations,\n" \
		"\e[3m-opt\e[0m targets produce a highly optimized binary, while\n" \
		"\e[3m-dbg\e[0m targets only use optimizations not hindering debugging.\n" \
		"Targets suffixed with \e[3m-verbose\e[0m generate binaries including\n" \
		"verbose output (via \e[3mDBG_VERBOSE\e[0m), making such targets useful for debugging.\n" \
		"To get a verbose make output, clear VERBOSE, e.g. \e[3mmake VERBOSE=\e[0m.\n" \
		"The following targets are available (each target can be suffixed by \e[3m-noopt\e[0m\n" \
		"and \e[3m-verbose\e[0m):\n\n" \
		"	\e[3mall\e[0m      Builds $(PROJECT), generating an ELF binary\n\n" \
		"	\e[3mdoc\e[0m      Builds the documention (doc/html/index.html)\n" \


# Print warnings, if appropriate
ifeq (,$(COMPILER))
$(warning Unknown (and potentially unsupported) compiler "$(CXX)"!)
endif


# Include dependency files (generated via gcc flag -MM)
ifneq ($(MAKECMDGOALS),clean)
-include $(DEP_FILES)
endif


# Phony targets
.PHONY: clean doc help