[2.6 patch] add -Werror-implicit-function-declaration to CFLAGS

[Adrian Bunk]

On Thu, Nov 10, 2005 at 06:24:43PM -0800, Andrew Morton wrote:
> Adrian Bunk <bunk at stusta.de> wrote:
> >
> > On Thu, Nov 10, 2005 at 04:28:57AM -0800, Andrew Morton wrote:
> > > Adrian Bunk <bunk at stusta.de> wrote:
> > > >
> > > > Currently, using an undeclared function gives a compile warning, but it 
> > > >  can lead to a nasty runtime error if the prototype of the function is 
> > > >  different from what gcc guessed.
> > > > 
> > > >  With -Werror-implicit-function-declaration, we are getting an immediate 
> > > >  compile error instead.
> > > > 
> > > >  There will be some compile errors in cases where compilation previously
> > > >  worked because the undefined function wasn't called due to gcc dead code
> > > >  elimination, but in these cases a proper fix doesnt harm.
> > > > 
> > > 
> > > Sorry, I need to build allmodconfig kernels on wacky architectures (eg
> > > ppc64) and this patch is killing me.
> > 
> > Can you send me the list of compile errors so that I can work on fixing 
> > them?
> > 
> 
> No handily, sorry.   Missing virt_to_bus() is the typical problem.
>

But in this case -Werror-implicit-function-declaration doesn't create 
new compile errors, it only moves compile errors from compile time to 
link or depmod time - which is IMHO not a bad change.

If you really want to keep the status quo, you can still steal the 
following from sparc64:
  extern unsigned long virt_to_bus_not_defined_use_pci_map(volatile void *addr);
  #define virt_to_bus virt_to_bus_not_defined_use_pci_map
  extern unsigned long bus_to_virt_not_defined_use_pci_map(volatile void *addr);
  #define bus_to_virt bus_to_virt_not_defined_use_pci_map

Would a patch to mark the ISA legacy functions as __deprecated be OK?

This might give some motivation for people to convert drivers and would 
avoid new code like the recently introduced kexec to use this obsolete 
API.

> The cross-tools at http://developer.osdl.org/dev/plm/cross_compile/ are
> quite simple to install.

Thanks, I've tried it.

Other problems I found until I gave up on compiling:
- a problem in sk98lin indirectly corrected by my SkPciWriteCfgDWord() 
  patch
- drivers/net/wireless/tiacx/: missing #include <linux/vmalloc.h>'s
  (see my patch) - this seems to be a real bug

cu
Adrian

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