Re: gcc-3.3.2 for Netwinder

[Daniel Kegel <dank at kegel dot com>]

Craig A. Vanderborgh wrote:
> > > The netwinder is using "NWFPE", the kernel floating point emulator, to
> > > do the floating point stuff.
> > >
> > > When I cross-compile (on x86linux to arm) I can get the correct code
> > > generated if I specify -mhard-float.  ...
> > > So my problem is really that the crosstool build does not seem to be
> > > able to build glibc with "hard float" so that the linked binary (built
> > > using the cross-compiler) is compatible with the NWFPE libc.so on the
> > > netwinder.
> >
> > Did you try adding -mhard-float to TARGET_CFLAGS in arm.dat before
> > building crosstool? ...
>
> I am using crosstool-0.27, and my current ".dat" file looks like this:

Please try crosstool-0.28-rc30.  It has arm fixes.

> KERNELCONFIG=$PWD/arm.config
> TARGET=arm-elf-linux
> TARGET_CFLAGS="-march=armv4 -O"
> GCC_EXTRA_CONFIG="--with-float=hard"

I had problems in the distant past with gcc defaults in GCC_EXTRA_CONFIG
not applying for the glibc or stdlibc++ built by crosstool, so it might be worth
also setting
TARGET_CFLAGS="-march=armv4 -O -mhard-float"
in that file.

> The problem I am having is that evidently the netwinder requires the
> "hard-float" configuration of gcc, but I cannot compile glibc without
> the "--without-fp" option, and thus it is not possible to link
> executables with the cross toolchain.
>
> I should point out that I CAN build working floating point programs as
> long as I build just the object using the crosstool-built GCC specifying
> -mhard-float on the command line and then link it on the netwinder.
>
> Right now, I am trying the approach of commenting out the missing
> instructions (e.g. sfmea) in the glibc sources.  This might work and I
> will keep you posted.  But is there a better approach??  Is there some
> legit configuration settings I can use to build the unadulterated glibc
> sources for the netwinder?

Hrm, I dunno.  I wonder if there are any interesting patches in
ftp://fr2.rpmfind.net/linux/netwinder.org/netwinder/SRPMS/base/nw9/glibc-2.3.2-27.9_nw3.src.rpm
Have you looked in glibc cvs to see if the missing instructions are used?
Why are the instructions missing?
Do we need to configure binutils differently?
- Dan

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