[add] laos using xv6-riscv thought

laos/src/util/Makefile

@@ -0,0 +1,21 @@
+CURNAME		:= util
+BUILD_DIR	:= $(TOP_BUILD_DIR)/$(CURNAME)
+
+CSRC		:= $(wildcard *.c)
+OBJS		:= $(patsubst %.c,%.o,$(CSRC))
+BUILD_OBJS	:= $(addprefix $(BUILD_DIR)/,$(OBJS))
+
+.PHONY: build all message
+
+all: message build
+
+$(BUILD_DIR):
+	@mkdir -p $(BUILD_DIR)
+
+$(BUILD_OBJS): $(BUILD_DIR)/%.o:%.c $(BUILD_DIR)
+	@$(CC) -c -o $@ $< $(CPPFLAGS) $(CFLAGS)
+
+build: $(BUILD_OBJS)
+
+message:
+	@echo "building $(CURNAME)"

laos/src/util/memops.c

@@ -0,0 +1 @@
+#include <assert.h>