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##
# By default everything is silent. If you want to change this behavior, simply
# assign V=1 when calling make.
V =
ifeq ($(strip $(V)),)
E = @echo
Q = @
else
E = @\#
Q =
endif
##
# Paths.
SRC = $(wildcard src/*.S src/*.c)
OBJ = $(patsubst %.c,%.o,$(patsubst %.S,%.o,$(SRC)))
EXE = init
ARCH = riscv
LINUX_SOURCE ?=
KERNEL = $(LINUX_SOURCE)/arch/$(ARCH)/boot/Image
##
# Compile options. You can use CROSS_COMPILE just like on the Linux Kernel. You
# can also determine the ISA to be used, which defaults to my VisionFive2 board.
# I did not go too much into the rabbit hole of platform-specific flags because
# everything is in assembly anyways and everything is statically linked. Hence
# no `-mcpu`, no `-mtune`, no funny business.
CC = $(CROSS_COMPILE)gcc$(CC_SUFFIX)
LD = $(CROSS_COMPILE)gcc$(CC_SUFFIX)
ISA ?= rv64imafdc_zicntr_zicsr_zifencei_zihpm_zca_zcd_zba_zbb
INCLUDES = -Iinclude/
ASFLAGS = -march=$(ISA) -mabi=lp64d $(INCLUDES)
CCFLAGS = $(ASFLAGS) -std=gnu17
WARNINGS = -Werror -Wall -Wextra -Wcast-align -Wcast-qual -Winit-self \
-Wmissing-include-dirs -Wredundant-decls -Wshadow -Wsign-conversion \
-Wswitch-default -Wundef -Wunreachable-code
CCFLAGS += $(WARNINGS)
LDFLAGS = -static $(INCLUDES)
##
# Optional parameters for QEMU and gdb.
QEMU_FLAGS ?=
GDB_EXTRA_FLAGS ?=
# You can pass an optional `DEBUG` variable to manipulate the build type.
DEBUG ?=
ifeq ($(strip $(DEBUG)),)
CCFLAGS += -O3
else
CCFLAGS += -g -O0 -D__DEBUG__
endif
# Image being mounted for QEMU's consumption.
MOUNT_DEST_DIR ?= /mnt/pudc
MOUNT_DEST_IMG ?= disk.img
##
# Targets
.PHONY: all
all: clean $(EXE)
.PHONY: $(EXE)
$(EXE): $(OBJ)
$(E) " LD " $@
$(Q) $(LD) $(LDFLAGS) $+ -o $(EXE)
.c.o:
$(E) " CC " $(basename $@)
$(Q) $(CC) $(CCFLAGS) -c $< -o $@
.S.o:
$(E) " CC " $(*F)
$(Q) $(CC) $(ASFLAGS) -c $< -o $@
# Ensure that we have LINUX_SOURCE defined.
.PHONY: qemu_env
qemu_env:
$(if $(wildcard $(LINUX_SOURCE)),,$(error The 'LINUX_SOURCE' environment variable must be set to a non-empty value.))
# Insert the built $(EXE) into the image to be mounted via QEMU.
.PHONY: qemu_prepare_disk
qemu_prepare_disk:
$(E) " DISK $(MOUNT_DEST_IMG)"
$(Q) sudo mkdir -p $(MOUNT_DEST_DIR)
$(Q) sudo mount -o loop $(MOUNT_DEST_IMG) $(MOUNT_DEST_DIR)
$(Q) sudo mkdir -p $(MOUNT_DEST_DIR)/bin/ $(MOUNT_DEST_DIR)/dev/ \
$(MOUNT_DEST_DIR)/etc/ $(MOUNT_DEST_DIR)/proc/ $(MOUNT_DEST_DIR)/run/pudc/ \
$(MOUNT_DEST_DIR)/sbin/ $(MOUNT_DEST_DIR)/sys/ $(MOUNT_DEST_DIR)/tmp/
$(Q) sudo cp $(EXE) $(MOUNT_DEST_DIR)/sbin/$(EXE)
$(Q) sudo umount $(MOUNT_DEST_DIR)
# Run QEMU by using the built $(KERNEL) and the $(MOUNT_DEST_IMG), which
# contains the $(EXE) binary as '/sbin/init'.
.PHONY: qemu
qemu: qemu_env $(EXE) qemu_prepare_disk
$(E) " QEMU kernel=$(KERNEL)"
$(Q) qemu-system-riscv64 -machine virt -smp 4 -m 8G -kernel $(KERNEL) \
-nographic $(QEMU_FLAGS) \
-drive file=$(MOUNT_DEST_IMG),format=raw,if=virtio \
-append "root=/dev/vda rw console=ttyS0"
.PHONY: clean
clean:
$(Q) rm -f $(OBJ) $(EXE)
.PHONY: lint
lint:
$(Q) git ls-files *.c *.h | xargs clang-format --dry-run --Werror
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