Subject: Re: soft-float builds
To: Simon Burge <>
From: Jason R Thorpe <>
List: tech-toolchain
Date: 05/30/2001 07:37:23
On Wed, May 30, 2001 at 10:22:08PM +1000, Simon Burge wrote:

 > What I was thinking was something along the lines of a
 > 	MKSOFTFLOAT=	yes|no
 > make variable, which would do things like add "-msoft-float" to the CC
 > and CXX (and FC?) variables, and be used in the libc/arch/* makefiles
 > (or even just libc/Makefile) to enable softfloat support in libc.
 > Any comments on this, or better ways to do it?

That sounds fine.

 > This raises a further question about whether or not we should have a
 > separate MACHINE_ARCH for softfloat-built userlands and what it should
 > be called (soft<arch>, soft-<arch>, ...).  Any ideas here will be
 > appreciated...

Yes, esp. for e.g. PowerPC, where it changes the ABI for e.g. stdarg.  Do
you have kernel FP emulation for FPU-less PowerPCs?  If so, then you can
still run FPU-using PowerPC code by emulating the register accesses, but
that'll be slow...

Actually, are there ELF header bits that indiciate "uses FPU"?  I know
there are for MIPS...

        -- Jason R. Thorpe <>