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

From: Andrew Morton
Date: Tue Apr 10 2007 - 21:48:15 EST


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

> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> 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().

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