Question

我正在用C编写一个基本内核模块来试验虚拟机。目前我的所有代码都运行正常，但是在编译时我也收到内核头文件的警告，这导致我发现很难看到我可能会意外忽略的任何错误。

我找到了关于如何禁用外部库警告的答案here，这表明我需要使用GCC -isystem {dir}标志，但这似乎不起作用。有人能指出我做错了什么吗？这是我目前的Makefile：

obj-m += module.o
module-objs := \
    src/main.o \
    src/logger.o

EXTRA_CFLAGS += -fno-stack-protector
EXTRA_CFLAGS += -fno-pie
EXTRA_CFLAGS += -isystem /usr/src/kernels/*  # This doesn't seem to work, I still end up getting warnings

all:
    make -C /lib/modules/{my kernel}/build M=$(PWD) modules
clean:
    make -C /lib/modules/{my kernel}/build M=$(PWD) clean

我得到的警告示例：

make -C /lib/modules/{my kernel}/build M=/root/Documents/Projects/TestKernelMod modules
make[1]: Entering directory '/usr/src/kernels/{my kernel}'
/usr/src/kernels/{my kernel}/arch/x86/Makefile:81: stack protector enabled but no compiler support
  CC [M]  /root/Documents/Projects/TestKernelMod/src/main.o
In file included from /usr/src/kernels/{my kernel}/arch/x86/include/asm/smp.h:13:0,
                 from /usr/src/kernels/{my kernel}/arch/x86/include/asm/mmzone_64.h:12,
                 from /usr/src/kernels/{my kernel}/arch/x86/include/asm/mmzone.h:4,
                 from include/linux/mmzone.h:850,
                 from include/linux/gfp.h:4,
                 from include/linux/kmod.h:22,
                 from include/linux/module.h:13,
                 from /root/Documents/Projects/TestKernelMod/src/main.c:2:
/usr/src/kernels/{my kernel}/arch/x86/include/asm/apic.h: In function ‘native_apic_msr_read’:
/usr/src/kernels/{my kernel}/arch/x86/include/asm/apic.h:150:11: warning: variable ‘high’ set but not used [-Wunused-but-set-variable]
  u32 low, high;
           ^~~~
/usr/src/kernels/{my kernel}/arch/x86/include/asm/apic.h: In function ‘x2apic_enabled’:
/usr/src/kernels/{my kernel}/arch/x86/include/asm/apic.h:190:11: warning: variable ‘msr2’ set but not used [-Wunused-but-set-variable]
  int msr, msr2;
           ^~~~

Answer 1

将V=1添加到make命令行以查看正在执行的实际命令。

您会发现make不会为您扩展通配符。您使用文字*给出的路径并不指向任何真实目录。请参阅使用$(wildcard)进行展开或放入正确的路径。

Makefile在编译内核模块时忽略'-isystem'标志

1 个答案: