VFP vs. FPA for ARM?

[Steven Scholz <steven dot scholz at imc-berlin dot de>]

Hi there,

a while back a had problems with with the byte order of doubles on an ARM9 
system.

Nicolas Pitre wrote me:

> > Yes.  On ARM, the two 32bit words of a double are themselves encoded
> > in native endian order, but the most significant word is always first.
>
> And for completeness, this is true only for FPA ordering.  The new VFP 
> ordering uses native memory ordering which is the same as i386 for litle 
> endian, or ppc for big endian, as anyone would normally expect.
>
> The kernel FP emulators are emulating a FPA coprocessor though.
> When soft-float is used, it can be configured to use either FPA or VFP 
> ordering.

Since I built my toolchain with crosstool using

KERNELCONFIG=`pwd`/arm.config
TARGET=arm-softfloat-linux-gnu
TARGET_CFLAGS="-O"
GCC_EXTRA_CONFIG="--with-float=soft"
GLIBC_EXTRA_CONFIG="--without-fp"
BINUTILS_DIR=binutils-2.15
GCC_DIR=gcc-3.3.3
GLIBC_DIR=glibc-2.3.3
LINUX_DIR=linux-2.6.10

I'd like to ask a few questions here:

1. "When soft-float is used" means the glibc, not the gcc !?
2. When I use soft-float then kernel FP emulator is not used !?
3. Which ordering is configured by crosstool?
4. How can I change that?

Thanks.

--
Steven





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