[Buildroot] [PATCH 1/2] powerpc/spe: tweak glibc/eglibc/uclibc combinations

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Thu Sep 11 20:57:15 UTC 2014

Dear Gustavo Zacarias,

On Thu, 11 Sep 2014 08:56:31 -0300, Gustavo Zacarias wrote:
> Since (e)glibc 2.19+ PowerPC SPE changed ABI conventions for sanity.
> In the good old days hard-float was used, it sounds good on paper until
> you account for the e500v1/v2 differences, with v1 being a fpu that does
> only single-precision math.
> So the ABI changed to make it soft-float and the libc (or libm) handle
> that deficiency in software if required, making old precompiled binaries
> incompatible (of no concern for buildroot since we've got no precompiled
> binary blobs for SPE in packages).

I'm not sure to fully understand: is PowerPC really using *soft-float*
as in all floating point operations are emulated in software? Or is it
a difference similar to the difference between hardfp and softfp on ARM
(both use the FPU and floating point instructions, it's only a
different ABI, where hardfp passes floating point arguments in floating
point registers, while softfp passes floating point arguments in
integer registers).


Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering

More information about the buildroot mailing list