Re: [patch] arch-specific cond_syscall usage issues

[Andrew Morton <akpm@osdl.org>]

Matt Mackall <mpm@selenic.com> wrote:
>
>  Experimenting with trying to use cond_syscall for a few arch-specific
>  syscalls, I discovered that it can't actually be used outside the file
>  in which sys_ni_syscall is declared because the assembler doesn't feel
>  obliged to output the symbol in that case:
> 
>  weak.c:
> 
>  #define cond_syscall(x) asm(".weak\t" #x "\n\t.set\t" #x ",sys_ni_syscall");
>  cond_syscall(sys_foo);
> 
>  $ nm weak.o
>           U sys_ni_syscall
> 
>  One arch (PPC) is apparently trying to use cond_syscall this way
>  anyway, though it's probably never been actually tested as the above
>  test was done on a PPC.

So why does the PPC kernel successfully link?