[PATCH] Fix allnoconfig build with gcc4

[PATCH] Fix allnoconfig build with gcc4

[mikukkon]

It seems that git commit 20380731bc2897f2952ae055420972ded4cd786e breaks
allnoconfig build with gcc4:

  CC      init/main.o
In file included from include/linux/netdevice.h:29,
		   from include/net/sock.h:48,
		   from init/main.c:50:
include/linux/if_ether.h:114: error: array type has incomplete element type

The "normal" fix of replacing foo[] with *foo would is not trivial, but
simply removing the offending line is.

Signed-off-by: Mika Kukkonen <mikukkon@iki.fi>

Index: linux-2.6/include/linux/if_ether.h
===================================================================
--- linux-2.6.orig/include/linux/if_ether.h
+++ linux-2.6/include/linux/if_ether.h
@@ -111,7 +111,6 @@ static inline struct ethhdr *eth_hdr(con
 	return (struct ethhdr *)skb->mac.raw;
 }
 
-extern struct ctl_table ether_table[];
 #endif
 
 #endif	/* _LINUX_IF_ETHER_H */

Re: [PATCH] Fix allnoconfig build with gcc4

[Linus Torvalds]

On Sat, 10 Sep 2005 mikukkon@iki.fi wrote:
>
> It seems that git commit 20380731bc2897f2952ae055420972ded4cd786e breaks
> allnoconfig build with gcc4:
> 
>   CC      init/main.o
> In file included from include/linux/netdevice.h:29,
> 		   from include/net/sock.h:48,
> 		   from init/main.c:50:
> include/linux/if_ether.h:114: error: array type has incomplete element type
> 
> The "normal" fix of replacing foo[] with *foo would is not trivial, but
> simply removing the offending line is.
> 
> Signed-off-by: Mika Kukkonen <mikukkon@iki.fi>

No, this would cause a compile error if CONFIG_NET and CONFIG_SYSCTL is
enabled (because sysctl_net.c needs that declaration).

So the correct solution is apparently either one of

 - always declare an empty "struct ctl_table" regardless of whether SYSCTL 
   is enabled or not.

   This might be a good idea, since it probably allows more code to be 
   compiled without checking for CONFIG_SYSCTL.

 - put the ether_table[] declaration inside a #ifdef CONFIG_SYSCTL.

Maybe somebody else has a stronger opinion than I do about which of these 
is the right solution.

		Linus

Re: [PATCH] Fix allnoconfig build with gcc4

[Mika Kukkonen]

On 9/11/05, Linus Torvalds <torvalds@osdl.org> wrote:
> 
> 
(...)
> No, this would cause a compile error if CONFIG_NET and CONFIG_SYSCTL
> is enabled (because sysctl_net.c needs that declaration).

Ah yes. I got confused by googling which showed that there are some issues
with these declarations and gcc4 (see for example this thread:
http://gcc.gnu.org/ml/gcc/2005-02/msg00053.html).

> So the correct solution is apparently either one of
> 
>  - always declare an empty "struct ctl_table" regardless of whether SYSCTL
>    is enabled or not.
> 
>    This might be a good idea, since it probably allows more code to be
>    compiled without checking for CONFIG_SYSCTL.
> 
>  - put the ether_table[] declaration inside a #ifdef CONFIG_SYSCTL.

core_table in include/net/sock.h uses the latter option, so I'll send
you a patch
for that (with better email client).

--MiKu