On Mon, Sep 10, 2007 at 01:08:12PM +0200, Johannes Berg wrote: > On Sat, 2007-09-08 at 14:01 +0100, Christoph Hellwig wrote: > > > Yes. It means a variable is declared in multiple places and the linker > > merges it for you. The fix is to make sure these are declared extern in > > all places but one. > > Interesting. So it's missing in a header file but sparse doesn't warn > about it like it does with functions that aren't declared nor static? No. Say you have the following case: ----------- foo.h ------------ int foo; ----------- foo1.c ----------- #include "foo.h" ----------- foo2.c ----------- #include "foo.h" --------- Makefile ----------- obj-m += foo.o foo-y += foo1.o foo2.o This gives you a foo COMMON symbol. But at least on i386 the kernel is compiled with -fno-common so you get a warning like: /home/hch/test/foo1.o:(.bss+0x0): multiple definition of `foo' /home/hch/test/foo2.o:(.bss+0x0): first defined here When adding -fcommon to EXTRA_FLAGS I get what you saw in this thread: WARNING: "foo" [/home/hch/test/foo] is COMMON symbol I wonder how the driver build managed to override our global -fno-common setting. - To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
