[OE-core] [PATCH] eglibc_2.13: Add support for handling sqrt & sqrtf on powerpc

[Kumar Gala]

On Aug 1, 2011, at 9:53 AM, Mark Hatle wrote:

> On 8/1/11 9:26 AM, Kumar Gala wrote:
>> Some of powerpc's dont support the fsqrt[s] instructions so we need an
>> implementation of the library functions for those processors.
>> 
>> Signed-off-by: Kumar Gala <galak at kernel.crashing.org>
>> ---
>> .../recipes-core/eglibc/eglibc-2.13/ppc-sqrt.patch |  538 ++++++++++++++++++++
>> meta/recipes-core/eglibc/eglibc_2.13.bb            |    3 +-
>> 2 files changed, 540 insertions(+), 1 deletions(-)
>> create mode 100644 meta/recipes-core/eglibc/eglibc-2.13/ppc-sqrt.patch
> 
> I'm a bit confused by this patch.  Why is gcc even generating (or trying to) the
> fsqrt instructions on cores that don't have it?  Did someone optimize gcc so
> that it always requires fsqrt on PPC?  (This is horribly broken behavior BTW...)
> 
> As for the patch, I don't object.. but this just looks like the wrong solution
> to me..
> 

Mark, the issue isn't w/gcc but glibc itself.  It will use inline asm of the 'fsqrt[s]' instruction.  This we need a different implementation of the math lib functions for these cores.

- k