Re: link error : 2.6.21-rc6-mm1 for s390

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 10 Apr 2007 18:36:29 -0700 (PDT)
David Miller <davem@davemloft.net> wrote:

> From: Andrew Morton <akpm@linux-foundation.org>
> Date: Tue, 10 Apr 2007 18:29:37 -0700
> 
> > git-net.patch implements generic lib/div64.c, but s390 also has a
> > private one.  Presumably the appropriate fix is to remove s390's
> > private implementation within davem's tree.
> 
> The s390 version seems to be optimized in assembler for that
> processor, therefore we should probably instead elide the
> generic version on s390.

We're sure that it has the same API?

> How about something like this?
> 
> diff --git a/include/asm-s390/div64.h b/include/asm-s390/div64.h
> index 6cd978c..21aea15 100644
> --- a/include/asm-s390/div64.h
> +++ b/include/asm-s390/div64.h
> @@ -1 +1,2 @@
>  #include <asm-generic/div64.h>
> +#define HAVE_ARCH_DIV64_32
> diff --git a/lib/div64.c b/lib/div64.c
> index 74f0c8c..5b480fa 100644
> --- a/lib/div64.c
> +++ b/lib/div64.c
> @@ -23,6 +23,8 @@
>  /* Not needed on 64bit architectures */
>  #if BITS_PER_LONG == 32
>  
> +#ifndef HAVE_ARCH_DIV64_32
> +
>  uint32_t __div64_32(uint64_t *n, uint32_t base)
>  {
>  	uint64_t rem = *n;
> @@ -58,6 +60,8 @@ uint32_t __div64_32(uint64_t *n, uint32_t base)
>  
>  EXPORT_SYMBOL(__div64_32);
>  
> +#endif /* !(HAVE_ARCH_DIV64_32) */
> +
>  /* 64bit divisor, dividend and result. dynamic precision */
>  uint64_t div64_64(uint64_t dividend, uint64_t divisor)
>  {

attribute(weak) would give a nicer result?

We'd also need to remove s390's EXPORT_SYMBOL(__div64_32), so s390 ends up
using lib/div64.c's EXPORT_SYMBOL().