[uml-devel] Using compiler.h from uml userspace code (was: Re: uml build error)

[Blaisorblade <blaisorblade@yahoo.it>]

On Wednesday 18 January 2006 12:31, Andrew Morton wrote:
> Blaisorblade <blaisorblade@yahoo.it> wrote:
> > On Wednesday 18 January 2006 09:22, Andrew Morton wrote:
> > > arch/um/os-Linux/umid.c:319: warning: `__uml_help_set_uml_dir' defined
> > > but not used arch/um/os-Linux/umid.c:319: warning:
> > > `__uml_setup_set_uml_dir' defined but not used
> > > arch/um/os-Linux/umid.c:335: warning:
> > > `__uml_exitcall_remove_umid_dir' defined but not used
> >
> > I never see those things (gcc 3.4), there should be a attribute((used))
> > for them, however it's replicated from compiler.h, as it can't be
> > included.

> gcc-3.2.1

Yep, it wants attribute((unused)) instead of all other ones. Damn right.

Possible solutions below - akpm doesn't need to read this. Sam, instead, 
please do read and give an opinion.

Found it: we're using __attribute_used__ from /usr/include/sys/cdefs.h rather 
than from compiler.h, because we can't include that... and <sys/cdefs.h> is 
buggy for this (see below).

But I've found a way to reuse compiler.h! Sam, could this go in?

Index: linux-2.6.git/include/linux/compiler.h
===================================================================
--- linux-2.6.git.orig/include/linux/compiler.h
+++ linux-2.6.git/include/linux/compiler.h
@@ -39,9 +39,9 @@ extern void __chk_io_ptr(void __iomem *)
 #if __GNUC__ > 4
 #error no compiler-gcc.h file for this gcc version
 #elif __GNUC__ == 4
-# include <linux/compiler-gcc4.h>
+# include "compiler-gcc4.h"
 #elif __GNUC__ == 3
-# include <linux/compiler-gcc3.h>
+# include "compiler-gcc3.h"
 #else
 # error Sorry, your compiler is too old/not recognized.
 #endif
@@ -50,7 +50,7 @@ extern void __chk_io_ptr(void __iomem *)
  * coming from above header files here
  */
 #ifdef __INTEL_COMPILER
-# include <linux/compiler-intel.h>
+# include "compiler-intel.h"
 #endif

 /*


With that in, just symlinking include/linux/compiler-*.h into arch/um/include 
would work well!

We prefer to avoid them included as <linux/compiler-*.h> because it could 
conflict with host headers, unless it's possible to have our headers searched 
before host ones.

==== <sys/cdefs.h>
I discovered that /usr/include/sys/cdefs.h has this define (which is likely 
the used definition!):

/* At some point during the gcc 3.1 development the `used' attribute
   for functions was introduced.  We don't want to use it unconditionally
   (although this would be possible) since it generates warnings.  */
#if __GNUC_PREREQ (3,1)
# define __attribute_used__ __attribute__ ((__used__))
# define __attribute_noinline__ __attribute__ ((__noinline__))
#else
# define __attribute_used__ __attribute__ ((__unused__))
# define __attribute_noinline__ /* Ignore */
#endif

while include/linux/compiler-gcc3.h tests for different minor (it requires 
>=3.3).
-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	

	
		
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