Floating point problems when building for ARM v5

Floating point problems when building for ARM v5

[Brian Clarke]

Hello all,

I am attempting to use a GCC 3.4.2 based ARM toolchain (binutils-2.15, 
newlib-1.12.0) to build for both v4 and v5 instruction targets.

When building for a v4 target all is well, the toolchain's libs (libc, 
libgcc) clain to be built for FPA floating point as do my object files 
and the code runs fine on the target.

When I try to build for a v5 target (actually ARM926EJ-S, which has no 
hardware FP support) the linker complains about floating point 
conflicts. The toolchain libs are again FPA, but my object files are VFP 
format.

I've tried convincing the toolchain to build my libraries for FPA, via 
experimenting with -msoft-float, -mhard-float and -fp=2/3 but each time 
I still get VFP libraries. I tried specifying the -mfpu=fpa switch, but 
this is rejected by the compiler.

Can anyone suggest a way to get the toolchain to build FPA libraries?

I've also tried to understand how to build the toolchain so it will 
build VFP libraries (i.e. for libc, libgcc). I have specified 
--with-arch=armv5te to the configure scripts of gcc (pt1 and pt2), 
newlib and binutils. This has resulted in libgcc being built for VFP, 
but libc is still built for FPA, suggesting I need to provide some other 
option while configuring newlib. The options I'm currently giving to 
newlib are:

configure --target=arm-elf --with-arch=armv5te  --enable-multilib 
--enable-interwork --prefix=$(PREFIX-PATH) --exec-prefix=$(EXEC-PATH)

I expected to see multiple versions of libc etc. built due to the 
--enable-multilib option, but only one appears, with FPA as the floating 
point type. Can anyone suggest an option to specify to the newlib 
configure to produce VFP libraries? The newlib config-ml.in file doesn't 
seem to allow for selecting VFP.

Thanks,
Brian.

Re: Floating point problems when building for ARM v5

[Brian Clarke]

I take it nobody has encountered either of the problems I mentioned in 
my original post.

Have have since found solutions that have allowed me to build a working 
toolchain for ARMv5, but I have not discovered a way to make a common 
toolchain for v4 and v5.

Brian Clarke wrote:
> Hello all,
> 
> I am attempting to use a GCC 3.4.2 based ARM toolchain (binutils-2.15, 
> newlib-1.12.0) to build for both v4 and v5 instruction targets.
> 
> When building for a v4 target all is well, the toolchain's libs (libc, 
> libgcc) clain to be built for FPA floating point as do my object files 
> and the code runs fine on the target.
> 
> When I try to build for a v5 target (actually ARM926EJ-S, which has no 
> hardware FP support) the linker complains about floating point 
> conflicts. The toolchain libs are again FPA, but my object files are VFP 
> format.
> 
> I've tried convincing the toolchain to build my libraries for FPA, via 
> experimenting with -msoft-float, -mhard-float and -fp=2/3 but each time 
> I still get VFP libraries. I tried specifying the -mfpu=fpa switch, but 
> this is rejected by the compiler.
> 
> Can anyone suggest a way to get the toolchain to build FPA libraries?
> 
> I've also tried to understand how to build the toolchain so it will 
> build VFP libraries (i.e. for libc, libgcc). I have specified 
> --with-arch=armv5te to the configure scripts of gcc (pt1 and pt2), 
> newlib and binutils. This has resulted in libgcc being built for VFP, 
> but libc is still built for FPA, suggesting I need to provide some other 
> option while configuring newlib. The options I'm currently giving to 
> newlib are:
> 
> configure --target=arm-elf --with-arch=armv5te  --enable-multilib 
> --enable-interwork --prefix=$(PREFIX-PATH) --exec-prefix=$(EXEC-PATH)
> 
> I expected to see multiple versions of libc etc. built due to the 
> --enable-multilib option, but only one appears, with FPA as the floating 
> point type. Can anyone suggest an option to specify to the newlib 
> configure to produce VFP libraries? The newlib config-ml.in file doesn't 
> seem to allow for selecting VFP.
> 
> Thanks,
> Brian.
> 
>