Add DTS file

When you build using the command make ENABLE_SYSTEM=1 -j$(nproc),
the default target in the Makefile is invoked. At this stage, the
Device Tree Blob (DTB) should already be built before executing
rv32emu. Therefore, system.mk is included before the all target
in the Makefile.

Makefile

@@ -59,10 +59,6 @@ CFLAGS += $(CFLAGS_NO_CET)
 
 OBJS_EXT :=
 
-ifeq ($(call has, SYSTEM), 1)
-OBJS_EXT += system.o
-endif
-
 # Integer Multiplication and Division instructions
 ENABLE_EXT_M ?= 1
 $(call set-feature, EXT_M)
@@ -214,8 +210,9 @@ $(OUT)/emulate.o: CFLAGS += -foptimize-sibling-calls -fomit-frame-pointer -fno-s
 include mk/external.mk
 include mk/artifact.mk
 include mk/wasm.mk
+include mk/system.mk
 
-all: config $(BIN)
+all: config $(BUILD_DTB) $(BIN)
 
 OBJS := \
 	map.o \
@@ -242,18 +239,6 @@ ifeq ($(call has, GDBSTUB), 1)
 $(OBJS): $(GDBSTUB_LIB)
 endif
 
-# Peripherals for system emulation
-ifeq ($(call has, SYSTEM), 1)
-DEV_OUT := $(OUT)/devices
-DEV_SRC := src/devices
-$(DEV_OUT)/%.o: $(DEV_SRC)/%.c $(deps_emcc)
-	$(Q)mkdir -p $(DEV_OUT)
-	$(VECHO) "  CC\t$@\n"
-	$(Q)$(CC) -o $@ $(CFLAGS) $(CFLAGS_emcc) -c -MMD -MF $@.d $<
-DEV_OBJS := $(patsubst $(DEV_SRC)/%.c, $(DEV_OUT)/%.o, $(wildcard $(DEV_SRC)/*.c))
-deps += $(DEV_OBJS:%.o=%.o.d)
-endif
-
 $(OUT)/%.o: src/%.c $(deps_emcc)
 	$(VECHO) "  CC\t$@\n"
 	$(Q)$(CC) -o $@ $(CFLAGS) $(CFLAGS_emcc) -c -MMD -MF $@.d $<

mk/system.mk

@@ -0,0 +1,20 @@
+# Peripherals for system emulation
+ifeq ($(call has, SYSTEM), 1)
+DEV_OUT := $(OUT)/devices
+DEV_SRC := src/devices
+
+DTC ?= dtc
+$(OUT)/minimal.dtb: $(DEV_SRC)/minimal.dts
+	$(VECHO) " DTC\t$@\n"
+	$(Q)$(DTC) $^ -o $@
+BUILD_DTB := $(OUT)/minimal.dtb
+
+$(DEV_OUT)/%.o: $(DEV_SRC)/%.c $(deps_emcc)
+	$(Q)mkdir -p $(DEV_OUT)
+	$(VECHO) "  CC\t$@\n"
+	$(Q)$(CC) -o $@ $(CFLAGS) $(CFLAGS_emcc) -c -MMD -MF $@.d $<
+DEV_OBJS := $(patsubst $(DEV_SRC)/%.c, $(DEV_OUT)/%.o, $(wildcard $(DEV_SRC)/*.c))
+deps += $(DEV_OBJS:%.o=%.o.d)
+
+OBJS_EXT += system.o
+endif

src/riscv.h

@@ -15,7 +15,7 @@
 #if RV32_HAS(SYSTEM)
 #include "devices/plic.h"
 #include "devices/uart.h"
-#endif /* RV32_HAS(EXT_SYSTEM) */
+#endif /* RV32_HAS(SYSTEM) */
 
 #if RV32_HAS(EXT_F)
 #define float16_t softfloat_float16_t