On Fri, Feb 26, 2021 at 01:47:20PM +0000, Chris Down wrote: > Chris Down writes: > > I must confess I have no idea of the history of why it was `extern int` > > in the first place -- my fear was somehow we use cmpxchg.h from a > > different context. Do you have any idea? :-) > > Ok, found where it's introduced in the pre-git archives: "New file > asm-ia64/intrinsics.h." from David Mosberger <dav...@tiger.hpl.hp.com>, Dec > 9 2002. No indication why it's extern, but it's been there since the dawn of > ia64.
It's just a quirk of C. 'extern' is only meaningful when applied to variables. In the context of functions, extern int printk(char *fmt); int printk(char *fmt); are completely equivalent. Unless (as you've seen) there's then a static definition following the extern declaration.
