如何更正Makefile中的注释？ “混合隐式和普通规则：弃用语法”

Question

我的Makefile定义如下： -

TARGET = wfirewall
obj-m = $(TARGET).o

KDIR = /lib/modules/$(shell uname -r)/build
PWD = $(shell pwd)
default:
    make -C $(KDIR) SUBDIRS=$(PWD) modules
clean :
    rm -f $(TARGET).ko $(TARGET).o $(TARGET).mod.*

我收到了消息

root@debian:/firewall# make
make -C /lib/modules/3.16.0-4-586/build SUBDIRS=/firewall modules
make[1]: Entering directory '/usr/src/linux-headers-3.16.0-4-586'
Makefile:10: *** mixed implicit and normal rules: deprecated syntax
make[1]: Entering directory `/usr/src/linux-headers-3.16.0-4-586'
  Building modules, stage 2.
  MODPOST 1 modules
make[1]: Leaving directory '/usr/src/linux-headers-3.16.0-4-586'

看那个!!混合隐式和普通规则：弃用语法??? 任何帮助表示赞赏！