底层驱动开发

				# List of files in the vdso, has to be asm only for now								obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o								# Build rules								targets := $(obj-vdso64) vdso64.so				obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))								EXTRA_CFLAGS := -shared -s -fno-common -fno-builtin				EXTRA_CFLAGS +=  -nostdlib -Wl,-soname=linux-vdso64.so.1				EXTRA_AFLAGS := -D__VDSO64__ -s								obj-y += vdso64_wrapper.o				extra-y += vdso64.lds				CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)								# Force dependency (incbin is bad)				$(obj)/vdso64_wrapper.o : $(obj)/vdso64.so								# link rule for the .so file, .lds has to be first				$(obj)/vdso64.so: $(src)/vdso64.lds $(obj-vdso64)					$(call if_changed,vdso64ld)								# assembly rules for the .S files				$(obj-vdso64): %.o: %.S					$(call if_changed_dep,vdso64as)								# actual build commands				quiet_cmd_vdso64ld = VDSO64L $@				      cmd_vdso64ld = $(CC) $(c_flags) -Wl,-T $^ -o $@				quiet_cmd_vdso64as = VDSO64A $@				      cmd_vdso64as = $(CC) $(a_flags) -c -o $@ $